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Android之ListView异步加载图片且仅显示可见子项中的图片

發布時間：2024/8/24 Android 24 豆豆

生活随笔收集整理的這篇文章主要介紹了 Android之ListView异步加载图片且仅显示可见子项中的图片小編覺得挺不錯的,現在分享給大家,幫大家做個參考.

折騰了好多天，遇到 N 多讓人崩潰無語的問題，不過今天終于有些收獲了，這是實驗的第一版，有些混亂，下一步進行改造細分，先把代碼記錄在這兒吧。

網上查了很多資料，發現都千篇一律，抄來抄去，很多細節和完整實例都沒看到，只有自己一點點研究了，總體感覺 android 下面要顯示個圖片真不容易啊。

項目主要實現的功能：

異步加載圖片圖片內存緩存、異步磁盤文件緩存解決使用 viewHolder 后出現的圖片錯位問題優化列表滾動性能，僅顯示可見子項中的圖片無需固定圖片顯示高度，對高度進行緩存使列表滾動時不會因圖片高度變化而閃動，使滾動體驗更加流暢圖片動畫展示效果，新加載的圖片顯示透明漸變動畫

沒有涉及到下拉加載和刷新數據，目前還沒接觸到這些，而且已發現自定義 ListView 中如果有添加頂部和底部的拉動加載更多數據提示的 view ，將會導致 ListView 的 child 數量和 position 混亂，所以只有先簡單使用 ListView 來做個效果。

核心主要是三個文件：MainActivity.java, ZAsyncImageLoader.java, DiaryListAdapter.java

下面貼代碼：

MainActivity.java

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package com.ai9475.meitian; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.nio.charset.Charset; import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.Date; import java.util.HashMap; import java.util.Iterator; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.drawable.Drawable; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.os.Handler; import android.os.Looper; import android.support.v4.app.FragmentTransaction; import android.support.v7.app.ActionBar; import android.support.v7.app.ActionBarActivity; import android.util.JsonReader; import android.util.Log; import android.view.Menu; import android.view.View; import android.widget.AbsListView; import android.widget.AdapterView; import android.widget.ImageView; import android.widget.ListView; import android.widget.SimpleAdapter; import android.widget.TextView; import android.widget.Toast; import com.ai9475.meitian.adapter.DiaryListAdapter; import com.ai9475.util.ZAsyncImageLoader; import com.ai9475.util.ZHttpRequest; import com.ai9475.util.ZLog; import com.ai9475.widget.PullToRefreshListView; import org.apache.http.entity.ContentType; import org.apache.http.entity.mime.MultipartEntityBuilder; import org.apache.http.protocol.HTTP; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import org.json.JSONStringer; import org.w3c.dom.Text; public class MainActivity extends ActionBarActivity { ????private static final String TAG = "MainActivity"; ????private ListView mDiaryListView; ????private DiaryListAdapter mDiaryListAdapter; ????private ZAsyncImageLoader mAsyncImageLoader; ????private Handler handler = new Handler(); ????private int endId = 0; ????private boolean isScrolling = false; ????@Override ????protected void onCreate(Bundle savedInstanceState) ????{ ????????Log.d("main activity", "start"); ????????// 執行父級初始化方法 ????????super.onCreate(savedInstanceState); ????????// 讓 ActionBar 浮動在 Activity 上方進行半透明遮蓋 ????????//this.supportRequestWindowFeature(Window.FEATURE_ACTION_BAR_OVERLAY); ????????// 解析視圖數據 ????????this.setContentView(R.layout.activity_main); ????????AppManager.getInstance().addActivity(this); ????????this.mAsyncImageLoader = new ZAsyncImageLoader(); ????????this.mAsyncImageLoader.setIsUseDiskCache(true); ????????this.mAsyncImageLoader.setCacheDir(AppConfig.IMAGE_CACHE_PATH); ????????// 配置 ActionBar 相關 ????????final ActionBar bar = this.getSupportActionBar(); ????????// 標題 ????????bar.setTitle("Bar"); ????????// 返回按鈕 ????????//bar.setDisplayHomeAsUpEnabled(true); ????????// 應用徽標控制 ????????//bar.setDisplayUseLogoEnabled(false); ????????// 應用圖標控制 ????????//bar.setDisplayShowHomeEnabled(true); ????????// 標題欄控制 ????????//bar.setDisplayShowTitleEnabled(true); ????????// 設置 TABS 導航模式 ????????bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); ????????/* ????????bar.getHeight(); ????????final ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView); ????????ViewTreeObserver scvto = scrollView.getViewTreeObserver(); ????????if (scvto != null) { ????????????scvto.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() { ????????????????@Override ????????????????public boolean onPreDraw() { ????????????????????scrollView.setPadding( ????????????????????????????scrollView.getPaddingLeft(), ????????????????????????????bar.getHeight(), ????????????????????????????scrollView.getPaddingRight(), ????????????????????????????scrollView.getPaddingBottom() ????????????????????); ????????????????????return true; ????????????????} ????????????}); ????????}*/ ????????/*Fragment fragmentA = new FragmentTab(); ????????Fragment fragmentB = new FragmentTab(); ????????Fragment fragmentC = new FragmentTab(); ????????tabA.setTabListener(new MyTabsListener(fragmentA)); ????????tabB.setTabListener(new MyTabsListener(fragmentB)); ????????tabC.setTabListener(new MyTabsListener(fragmentC));*/ ????????bar.addTab(bar.newTab().setText("ATab").setTabListener(new MyTabsListener())); ????????bar.addTab(bar.newTab().setText("BTab").setTabListener(new MyTabsListener())); ????????bar.addTab(bar.newTab().setText("CTab").setTabListener(new MyTabsListener())); ????????/*//bar.setDisplayShowHomeEnabled(false); ????????//bar.setDisplayShowTitleEnabled(false); ????????// 頂部幀布局操作欄 ????????final FrameLayout topActBar = (FrameLayout) findViewById(R.id.topActionBar); ????????// 底部幀布局操作欄 ????????final FrameLayout bottomActBar = (FrameLayout) findViewById(R.id.bottomActionBar); ????????// 列表滾動視圖 ????????final ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView); ????????// 頂部操作欄綁定事件：同步設置滾動視圖頂部內邊距 ????????topActBar ????????????????.getViewTreeObserver() ????????????????.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() { ????????????????????@Override ????????????????????public boolean onPreDraw() { ????????????????????????scrollView.setPadding( ????????????????????????????????scrollView.getPaddingLeft(), ????????????????????????????????topActBar.getHeight(), ????????????????????????????????scrollView.getPaddingRight(), ????????????????????????????????scrollView.getPaddingBottom() ????????????????????????); ????????????????????????return true; ????????????????????} ????????????????}); ????????// 底部操作欄綁定事件：同步設置滾動視圖底部內邊距 ????????bottomActBar ????????????????.getViewTreeObserver() ????????????????.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() { ????????????????????@Override ????????????????????public boolean onPreDraw() { ????????????????????????scrollView.setPadding( ????????????????????????????????scrollView.getPaddingLeft(), ????????????????????????????????scrollView.getPaddingTop(), ????????????????????????????????scrollView.getPaddingRight(), ????????????????????????????????bottomActBar.getHeight() ????????????????????????); ????????????????????????return true; ????????????????????} ????????????????}); ????????*/ ????????//AppContext context = (AppContext) getApplicationContext(); ????????//context.test(); /* ????????ZAsyncImageLoader loader = new ZAsyncImageLoader(); ????????String url1 = "http://img.ai9475.com/data/attachment/images/meitian/c5/e4/59/c5e459f00dce21480c9941eefbb88f90_200.jpg"; ????????String url2 = "http://img.ai9475.com/data/attachment/images/meitian/f9/29/ee/f929ee1dd6af7b805744b9fb3f4f99b5_200.jpg"; ????????loader.loadDrawable(url1, new ZAsyncImageLoader.OnImageLoadListener() { ????????????@Override ????????????public void onLoaded(Drawable imageDrawable, String imageUrl) { ????????????????ImageView img = (ImageView) findViewById(R.id.showPic1); ????????????????img.setImageDrawable(imageDrawable); ????????????} ????????}); ????????loader.loadDrawable(url2, new ZAsyncImageLoader.OnImageLoadListener() { ????????????@Override ????????????public void onLoaded(Drawable imageDrawable, String imageUrl) { ????????????????ImageView img = (ImageView) findViewById(R.id.showPic2); ????????????????img.setImageDrawable(imageDrawable); ????????????} ????????});*/ ????????// 找到日記列表視圖對象 ????????this.mDiaryListView = (ListView) findViewById(R.id.diaryListCt); ????????new Thread(){ ????????????@Override ????????????public void run() { ????????????????Runnable runnable = new Runnable() { ????????????????????@Override ????????????????????public void run() { ????????????????????????loadDiaryListData(); ????????????????????} ????????????????}; ????????????????handler.post(runnable); ????????????} ????????}.start(); ????} ????/** ?????* 日記列表初始化 ?????*/ ????protected void initDiaryList(JSONArray diaryList) ????{ ????????Log.d("initDiaryList", "start"); ????????// 列表單元與數據的適配器生成 ????????this.mDiaryListAdapter = new DiaryListAdapter(this, this.mDiaryListView, this.mAsyncImageLoader, diaryList); ????????// 綁定列表數據單元適配器 ????????Log.d("initDiaryList", "setAdapter"); ????????this.mDiaryListView.setAdapter(this.mDiaryListAdapter); ????????Log.d("bindListViewEvents", "start"); ????????// 綁定日記列表事件 ????????this.bindListViewEvents(); ????????Log.d("DiaryListAdapter", "end"); ????} ????static int j = 0; ????/** ?????* 綁定日記列表事件 ?????*/ ????public void bindListViewEvents() ????{ ????????// 列表滾動事件 ????????this.mDiaryListView.setOnScrollListener(new AbsListView.OnScrollListener(){ ????????????@Override ????????????public void onScrollStateChanged(AbsListView absListView, int scrollState) ????????????{ ????????????????switch (scrollState) { ????????????????????case AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL: ????????????????????????ZLog.i(TAG, "OnScrollListener : SCROLL_STATE_TOUCH_SCROLL"); ????????????????????????mDiaryListAdapter.setIsSCrolling(true); ????????????????????????break; ????????????????????case AbsListView.OnScrollListener.SCROLL_STATE_FLING: ????????????????????????ZLog.i(TAG, "OnScrollListener : SCROLL_STATE_FLING"); ????????????????????????mDiaryListAdapter.setIsSCrolling(true); ????????????????????????break; ????????????????????case AbsListView.OnScrollListener.SCROLL_STATE_IDLE: ????????????????????????// 第一個可見 item 的 position ????????????????????????int first = mDiaryListView.getFirstVisiblePosition(); ????????????????????????// 最后一個可見 item 的 position ????????????????????????int last = mDiaryListView.getLastVisiblePosition(); ????????????????????????// 屏幕上可見 item 的總數 ????????????????????????int onScreenCount = mDiaryListView.getChildCount(); ????????????????????????int total = first + last; ????????????????????????ZLog.i(TAG, "OnScrollListener : SCROLL_STATE_IDLE => " + (j++) +", first: "+ first +", last: "+ last +", total: "+ total +", onScreenCount:"+ onScreenCount); ????????????????????????mDiaryListAdapter.setIsSCrolling(false); ????????????????????????mDiaryListAdapter.setPositionRange(first, last); ????????????????????????View child; ????????????????????????int position; ????????????????????????for (int i = 0; i < onScreenCount; i++) { ????????????????????????????position = first + i; ????????????????????????????if (mDiaryListAdapter.isInPrevPositionRange(position)) { ????????????????????????????????ZLog.i(TAG, "inPrevPositionRange position:"+ position); ????????????????????????????????continue; ????????????????????????????} ????????????????????????????// 獲取可見 item 子項的視圖容器對象 ????????????????????????????child = mDiaryListView.getChildAt(i); ????????????????????????????ImageView picPhoto = (ImageView) child.findViewById(R.id.picPhoto); ????????????????????????????ImageView avatar = (ImageView) child.findViewById(R.id.avatar); ????????????????????????????try { ????????????????????????????????ZLog.i(TAG, "load image i:"+ first); ????????????????????????????????mDiaryListAdapter.loadImage(picPhoto, avatar, mDiaryListAdapter.getItem(position)); ????????????????????????????} catch (JSONException e) { ????????????????????????????????AppException.io(e); ????????????????????????????} ????????????????????????} ????????????????????????break; ????????????????????default: ????????????????????????break; ????????????????} ????????????} ????????????@Override ????????????public void onScroll(AbsListView absListView, int first, int last, int total) { ????????????????//mDiaryListAdapter.setPositionLimit(first, last); ????????????????//ZLog.i(TAG, "OnScrollListener : onScroll => " + (j++) +", first: "+ first +", last: "+ last +", total:"+ total); ????????????} ????????}); ????????// 列表單元點擊事件 ????????ZLog.i(TAG, "diaryListInit : setOnItemClickListener"); ????????this.mDiaryListView.setOnItemClickListener(new AdapterView.OnItemClickListener() { ????????????@Override ????????????public void onItemClick(AdapterView adapterView, View view, int i, long l) { ????????????????getSupportActionBar().setTitle("點擊了: "+ i); ????????????} ????????}); ????????ZLog.i("DiaryListAdapter", "setOnRefreshListener"); ????????// 當向下拉動刷新時觸發列表更新事件 ????????/*this.mDiaryListView.setOnRefreshListener(new PullToRefreshListView.OnRefreshListener() { ????????????@Override ????????????public void onRefresh() { ????????????????getSupportActionBar().setTitle("執行加載…"); ????????????????loadDiaryListData(); ????????????????mDiaryListView.onRefreshComplete(); ????????????} ????????});*/ ????} ????public void loadDiaryListData() ????{ ????????ZLog.i(TAG, "loadDiaryListData : start"); ????????try { ????????????ZHttpRequest httpRequset = new ZHttpRequest(new ZHttpRequest.OnHttpRequestListener() { ????????????????@Override ????????????????public void onRequest(ZHttpRequest request) { ????????????????????ZLog.i(TAG, "request data : start"); ????????????????} ????????????????@Override ????????????????public void onSucceed(int statusCode, ZHttpRequest request) { ????????????????????// 創建每行數據的集合 ????????????????????ZLog.i(TAG, "request onSucceed : start"); ????????????????????try { ????????????????????????String content = request.getInputStream(); ????????????????????????if (content == null) { ????????????????????????????Toast.makeText(getApplicationContext(), "數據請求失敗", Toast.LENGTH_SHORT).show(); ????????????????????????????return; ????????????????????????} ????????????????????????JSONArray diaryList = new JSONArray(content); ????????????????????????/*if (asyncImageLoader.getMaxPosition() < 1) { ????????????????????????????asyncImageLoader.setPositionLimit(0, diaryList.length()); ????????????????????????}*/ ????????????????????????endId = ((JSONObject) diaryList.opt(diaryList.length() - 1)).getInt("id"); ????????????????????????initDiaryList(diaryList); ????????????????????} catch (IOException e) { ????????????????????????Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show(); ????????????????????} catch (JSONException e) { ????????????????????????Toast.makeText(getApplicationContext(), e.getMessage(), Toast.LENGTH_SHORT).show(); ????????????????????} ????????????????} ????????????????@Override ????????????????public void onFailed(int statusCode, ZHttpRequest request) { ????????????????????ZLog.i(TAG, "request onFailed : code"+ statusCode); ????????????????} ????????????}); ????????????httpRequset.get("http://m.ai9475.com/?con=meitian_app&endId=" + this.endId); ????????} catch (Exception e) { ????????????e.printStackTrace(); ????????????Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG).show(); ????????} ????} ????protected class MyTabsListener implements ActionBar.TabListener ????{ //??????? private Fragment fragment; //??????? public MyTabsListener(Fragment fragment) //??????? { //??????????? this.fragment = fragment; //??????? } ????????@Override ????????public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) ????????{ //??????????? ft.add(R.id.fragmentPlace, this.fragment, null); ????????} ????????@Override ????????public void onTabReselected(ActionBar.Tab arg0, FragmentTransaction arg1) { ????????????// TODO Auto-generated method stub ????????} ????????@Override ????????public void onTabUnselected(ActionBar.Tab arg0, FragmentTransaction arg1) { ????????????// TODO Auto-generated method stub ????????} ????} ????/** ?????* 配置 ActionBar ?????* ?????* @param menu ?????* @return ?????*/ ????public boolean onCreateOptionsMenu(Menu menu) ????{ ????????this.getMenuInflater().inflate(R.menu.main, menu); ????????return super.onCreateOptionsMenu(menu); ????} ????/*public void doClick(View view) ????{ ????????ZHttpRequest get = new ZHttpRequest(); ????????get ????????????????.setCharset(HTTP.UTF_8) ????????????????.setConnectionTimeout(5000) ????????????????.setSoTimeout(5000); ????????get.setOnHttpRequestListener(new ZHttpRequest.OnHttpRequestListener() { ????????????@Override ????????????public void onRequest(ZHttpRequest request) throws Exception { ????????????} ????????????@Override ????????????public String onSucceed(int statusCode, ZHttpRequest request) throws Exception { ????????????????return request.getInputStream(); ????????????} ????????????@Override ????????????public String onFailed(int statusCode, ZHttpRequest request) throws Exception { ????????????????return "GET 請求失敗：statusCode "+ statusCode; ????????????} ????????}); ????????ZHttpRequest post = new ZHttpRequest(); ????????post ????????????????.setCharset(HTTP.UTF_8) ????????????????.setConnectionTimeout(5000) ????????????????.setSoTimeout(10000); ????????post.setOnHttpRequestListener(new ZHttpRequest.OnHttpRequestListener() { ????????????private String CHARSET = HTTP.UTF_8; ????????????private ContentType TEXT_PLAIN = ContentType.create("text/plain", Charset.forName(CHARSET)); ????????????@Override ????????????public void onRequest(ZHttpRequest request) throws Exception { ????????????????// 設置發送請求的 header 信息 ????????????????request.addHeader("cookie", "abc=123;456=愛就是幸福;"); ????????????????// 配置要 POST 的數據 ????????????????MultipartEntityBuilder builder = request.getMultipartEntityBuilder(); ????????????????builder.addTextBody("p1", "abc"); ????????????????builder.addTextBody("p2", "中文", TEXT_PLAIN); ????????????????builder.addTextBody("p3", "abc中文cba", TEXT_PLAIN); ????????????????if (picPath != null && ! "".equals(picPath)) { ????????????????????builder.addTextBody("pic", picPath); ????????????????????builder.addBinaryBody("file", new File(picPath)); ????????????????} ????????????????request.buildPostEntity(); ????????????} ????????????@Override ????????????public String onSucceed(int statusCode, ZHttpRequest request) throws Exception { ????????????????return request.getInputStream(); ????????????} ????????????@Override ????????????public String onFailed(int statusCode, ZHttpRequest request) throws Exception { ????????????????return "POST 請求失敗：statusCode "+ statusCode; ????????????} ????????}); ????????TextView textView = (TextView) findViewById(R.id.showContent); ????????String content = "初始內容"; ????????try { ????????????if (view.getId() == R.id.doGet) { ????????????????content = get.get("http://www.baidu.com"); ????????????????content = "GET數據：isGet: " + (get.isGet() ? "yes" : "no") + " =>" + content; ????????????} else { ????????????????content = post.post("http://192.168.1.6/test.php"); ????????????????content = "POST數據：isPost" + (post.isPost() ? "yes" : "no") + " =>" + content; ????????????} ????????} catch (IOException e) { ????????????content = "IO異常：" + e.getMessage(); ????????} catch (Exception e) { ????????????content = "異常：" + e.getMessage(); ????????} ????????textView.setText(content); ????} ????public void doPhoto(View view) ????{ ????????destoryBimap(); ????????String state = Environment.getExternalStorageState(); ????????if (state.equals(Environment.MEDIA_MOUNTED)) { ????????????Intent intent = new Intent("android.media.action.IMAGE_CAPTURE"); ????????????startActivityForResult(intent, 1); ????????} else { ????????????Toast.makeText(MainActivity.this, "沒有SD卡", Toast.LENGTH_LONG).show(); ????????} ????} ????@Override ????protected void onActivityResult(int requestCode, int resultCode, Intent data) ????{ ????????Uri uri = data.getData(); ????????if (uri != null) { ????????????this.photo = BitmapFactory.decodeFile(uri.getPath()); ????????} ????????if (this.photo == null) { ????????????Bundle bundle = data.getExtras(); ????????????if (bundle != null) { ????????????????this.photo = (Bitmap) bundle.get("data"); ????????????} else { ????????????????Toast.makeText(MainActivity.this, "拍照失敗", Toast.LENGTH_LONG).show(); ????????????????return; ????????????} ????????} ????????FileOutputStream fileOutputStream = null; ????????try { ????????????// 獲取 SD 卡根目錄 ????????????String saveDir = Environment.getExternalStorageDirectory() + "/meitian_photos"; ????????????// 新建目錄 ????????????File dir = new File(saveDir); ????????????if (! dir.exists()) dir.mkdir(); ????????????// 生成文件名 ????????????SimpleDateFormat t = new SimpleDateFormat("yyyyMMddssSSS"); ????????????String filename = "MT" + (t.format(new Date())) + ".jpg"; ????????????// 新建文件 ????????????File file = new File(saveDir, filename); ????????????// 打開文件輸出流 ????????????fileOutputStream = new FileOutputStream(file); ????????????// 生成圖片文件 ????????????this.photo.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream); ????????????// 相片的完整路徑 ????????????this.picPath = file.getPath(); ????????????ImageView imageView = (ImageView) findViewById(R.id.showPhoto); ????????????imageView.setImageBitmap(this.photo); ????????} catch (Exception e) { ????????????e.printStackTrace(); ????????} finally { ????????????if (fileOutputStream != null) { ????????????????try { ????????????????????fileOutputStream.close(); ????????????????} catch (Exception e) { ????????????????????e.printStackTrace(); ????????????????} ????????????} ????????} ????} ????/** ?????* 銷毀圖片文件 ?????* ????private void destoryBimap() ????{ ????????if (photo != null && ! photo.isRecycled()) { ????????????photo.recycle(); ????????????photo = null; ????????} ????}*/ }

其中涉及到 scroll 滾動相關的事件，我一開始在這里折騰了好久，可以去看看我這篇文章：

Android 關于 OnScrollListener 事件順序次數的簡要分析

ZAsyncImageLoader.java

package com.ai9475.util; import android.graphics.drawable.Drawable; import android.os.Handler; import android.os.Message; import java.io.DataInputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.lang.ref.SoftReference; import java.net.HttpURLConnection; import java.net.URL; import java.util.Date; import java.util.HashMap; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; /** ?* 異步多線程加載圖片 ?* ?* Created by ZHOUZ on 14-2-7. ?*/ public class ZAsyncImageLoader { ????private static final String TAG = "ZAsyncImageLoader"; ????/** ?????* 線程池中的線程數量 ?????*/ ????private int mThreadSize = 5; ????/** ?????* 是否使用 SD 卡緩存圖片 ?????*/ ????private boolean mIsUseDiskCache = false; ????/** ?????* SD 卡上緩存的圖片有效期（單位:秒） ?????*/ ????private int mExpireTime = 86400; ????/** ?????* 圖片緩存文件目錄 ?????*/ ????private String mCachePath = null; ????/** ?????* 同步緩存已加載過的圖片，使用軟引用優化內存 ?????*/ ????private HashMap<string, softreference<drawable="">> mImageCaches = new HashMap<string, softreference<drawable="">>(); ????/** ?????* 使用線程池，根據 CPU 數量來動態決定可用線程數量 ?????*/ ????private ExecutorService mExecutorService = null; ????/** ?????* 設置 SD 卡中的圖片緩存有效時長（單位:秒） ?????* ?????* @param time ?????*/ ????public void setExpireTime(int time) { ????????this.mExpireTime = time; ????} ????/** ?????* 設置線程數量 ?????* ?????* @param size ?????*/ ????public void setThreadSize(int size) { ????????this.mThreadSize = size; ????} ????/** ?????* 設置是否使用 SD 卡緩存圖片 ?????* ?????* @param isUse ?????*/ ????public void setIsUseDiskCache(Boolean isUse) { ????????this.mIsUseDiskCache = isUse; ????} ????/** ?????* 設置緩存目錄 ?????* ?????* @param path ?????*/ ????public void setCacheDir(String path) { ????????this.mCachePath = path; ????} ????/** ?????* 獲取線程池管理器 ?????* ?????* @return ?????*/ ????public ExecutorService getExecutorService() { ????????if (this.mExecutorService == null) { ????????????if (this.mThreadSize < 1) { ????????????????this.mThreadSize = Runtime.getRuntime().availableProcessors() * 5; ????????????} ????????????this.mExecutorService = Executors.newFixedThreadPool(this.mThreadSize); ????????} ????????return this.mExecutorService; ????} ????/** ?????* 加載圖片的多線程控制 ?????* ?????* @param imageUrl ?????* @param tag ?????* @param listener ?????*/ ????public Drawable loadDrawable(final String imageUrl, final String tag, final OnImageLoadListener listener) ????{ ????????// 是否已緩存過圖片, 是則從緩存中直接獲取, 若緩存中數據丟失則重新遠程加載 ????????if (this.mImageCaches.containsKey(imageUrl)) { ????????????SoftReference<drawable> softReference = this.mImageCaches.get(imageUrl); ????????????if (softReference != null) { ????????????????Drawable drawable = softReference.get(); ????????????????if (drawable != null) { ????????????????????return drawable; ????????????????} ????????????} ????????} ????????// 異步多線程加載圖片后的數據傳遞處理 ????????final Handler handler = new Handler() { ????????????@Override ????????????public void handleMessage(Message message) { ????????????????if (message.what == 1) { ????????????????????listener.onLoaded((Drawable) message.obj, imageUrl, tag); ????????????????} else { ????????????????????listener.onFailed((IOException) message.obj, imageUrl, tag); ????????????????} ????????????} ????????}; ????????// 通過線程池來控制管理圖片加載 ????????this.getExecutorService().submit(new Runnable() { ????????????@Override ????????????public void run() { ????????????????Message msg; ????????????????try { ????????????????????Drawable drawable = loadImageFromUrl(imageUrl); ????????????????????mImageCaches.put(imageUrl, new SoftReference<drawable>(drawable)); ????????????????????msg = handler.obtainMessage(1, drawable); ????????????????} catch (IOException e) { ????????????????????msg = handler.obtainMessage(0, e); ????????????????} ????????????????handler.sendMessage(msg); ????????????} ????????}); ????????return null; ????} ????/** ?????* 加載遠程圖片或本地圖片緩存文件 ?????* ?????* @param imageUrl ?????* @return ?????* @throws IOException ?????*/ ????public Drawable loadImageFromUrl(String imageUrl) throws IOException ????{ ????????// 檢查 SD 卡是否可用并將圖片緩存到 SD 卡上 ????????if (mIsUseDiskCache && mCachePath != null) ????????{ ????????????File d = new File(mCachePath); ????????????if (! d.exists()) { ????????????????d.mkdirs(); ????????????} ????????????final File f = new File(mCachePath + ZHelper.md5(imageUrl)); ????????????long time = (new Date()).getTime(); ????????????long expire = time - (mExpireTime * 1000L); ????????????// 文件存在且在有效期內則直接讀取 ????????????if (f.exists() && f.lastModified() > expire) { ????????????????FileInputStream fis = new FileInputStream(f); ????????????????return Drawable.createFromStream(fis, "src"); ????????????} ????????????// 遠程加載圖片后寫入到 SD 卡上 ????????????InputStream i = this.getImageInputStream(imageUrl); ????????????if (i == null) { ????????????????return null; ????????????} ????????????final Drawable drawable = Drawable.createFromStream(i, "src"); ????????????// 將圖片異步寫入到本地 SD 卡中緩存, 避免阻塞UI線程, 導致圖片不能顯示 ????????????new Thread(new Runnable() { ????????????????@Override ????????????????public void run() { ????????????????????try { ????????????????????????InputStream i = ZFormat.drawable2InputStream(drawable); ????????????????????????DataInputStream in = new DataInputStream(i); ????????????????????????FileOutputStream out = new FileOutputStream(f); ????????????????????????byte[] buffer = new byte[1024]; ????????????????????????int byteRead; ????????????????????????while ((byteRead = in.read(buffer)) != -1) { ????????????????????????????out.write(buffer, 0, byteRead); ????????????????????????} ????????????????????????in.close(); ????????????????????????out.close(); ????????????????????} catch (IOException e) { ????????????????????????ZLog.d("write image cache IOException", e.getMessage()); ????????????????????????e.printStackTrace(); ????????????????????} ????????????????} ????????????}).start(); ????????????return drawable; ????????} ????????// 只讀取遠程圖片不緩存 ????????else { ????????????InputStream i = this.getImageInputStream(imageUrl); ????????????return Drawable.createFromStream(i, "src"); ????????} ????} ????/** ?????* 遠程加載圖片數據 ?????* ?????* @param imageUrl ?????* @return ?????* @throws IOException ?????*/ ????public InputStream getImageInputStream(String imageUrl) throws IOException ????{ ????????URL m = new URL(imageUrl); ????????HttpURLConnection conn = (HttpURLConnection) m.openConnection(); ????????conn.setRequestMethod("GET"); ????????conn.setUseCaches(false); ????????conn.setDoInput(true); ????????conn.setConnectTimeout(5000); ????????conn.setReadTimeout(30000); ????????conn.setInstanceFollowRedirects(true); ????????return conn.getInputStream(); ????} ????/** ?????* 加載圖片的事件監聽器 ?????*/ ????public interface OnImageLoadListener { ????????/** ?????????* 圖片加載完成事件處理 ?????????* ?????????* @param imageDrawable ?????????* @param imageUrl ?????????* @param tag ?????????*/ ????????public void onLoaded(Drawable imageDrawable, String imageUrl, String tag); ????????/** ?????????* 圖片加載失敗的事件處理 ?????????* ?????????* @param e ?????????* @param imageUrl ?????????* @param tag ?????????*/ ????????public void onFailed(IOException e, String imageUrl, String tag); ????} ????protected void finalize() ????{ ????????this.mExecutorService.shutdown(); ????} } </drawable></drawable></string,></string,>

DiaryListAdapter.java

package com.ai9475.meitian.adapter; import android.content.Context; import android.graphics.drawable.Drawable; import android.util.Log; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.view.animation.AlphaAnimation; import android.widget.AbsListView; import android.widget.BaseAdapter; import android.widget.ImageView; import android.widget.ListView; import android.widget.RelativeLayout; import android.widget.TextView; import android.widget.Toast; import com.ai9475.meitian.R; import com.ai9475.util.ZAsyncImageLoader; import com.ai9475.util.ZHelper; import com.ai9475.util.ZLog; import com.ai9475.util.ZUI; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import java.io.IOException; import java.util.ArrayList; import java.util.HashMap; import java.util.Map; /** ?* Created by ZHOUZ on 14-2-8. ?*/ public class DiaryListAdapter extends BaseAdapter implements AbsListView.RecyclerListener { ????private static final String TAG = "DiaryListAdapter"; ????private Context mContext; ????private ListView mDiaryListView; ????public View mConvertView; ????private ZAsyncImageLoader mAsyncImageLoader; ????private JSONArray mDiaryDataList = null; ????private boolean mIsScrolling = false; ????private int mFirstPosition = 0; ????private int mLastPosition = 0; ????private int mPrevFirstPosition = 0; ????private int mPrevLastPosition = 0; ????private HashMap<string, integer=""> mImagesHeight = new HashMap<string, integer="">(); ????public DiaryListAdapter(Context context, ListView listView, ZAsyncImageLoader imageLoader, JSONArray diaryList) ????{ ????????this.mContext = context; ????????this.mAsyncImageLoader = imageLoader; ????????this.mDiaryDataList = diaryList; ????????this.mDiaryListView = listView; ????} ????public void setIsSCrolling(boolean flag) ????{ ????????this.mIsScrolling = flag; ????} ????/** ?????* 當前列表加載到的日記總數 ?????* ?????* @return ?????*/ ????public int getCount() { ????????return this.mDiaryDataList == null ? 0 : this.mDiaryDataList.length(); ????} ????/** ?????* 可見單元位置對比是否處在在上次滾動可是范圍內 ?????* ?????* @param position ?????* @return ?????*/ ????public boolean isInPrevPositionRange(int position) { ????????// 初始化時直接返回 false ????????if (this.mPrevLastPosition == 0) return false; ????????// 檢測當前 item 的位置是否在上次滾動范圍內, 是則表示該 item 正處于屏幕可見狀態中無需重新加載 ????????return (position >= this.mPrevFirstPosition && position <= this.mPrevLastPosition) ? true : false; ????} ????/** ?????* 設置滾動后可見的起止項目序號 ?????* ?????* @param first ?????* @param last ?????*/ ????public void setPositionRange(int first, int last) { ????????// 保存上次滾動后的可見位置 ????????this.mPrevFirstPosition = this.mFirstPosition; ????????this.mPrevLastPosition = this.mLastPosition; ????????// 重置當前可見位置 ????????this.mFirstPosition = first; ????????this.mLastPosition = last; ????????ZLog.i(TAG, "setPositionLimit prevFirst: "+ mPrevFirstPosition +", prevLast: "+ mPrevLastPosition +", first: "+ mFirstPosition +", last: "+ mLastPosition); ????} ????/** ?????* 獲取當前列表單元的日記id ?????* ?????* @param position ?????* @return ????*/ ????public long getItemId(int position) { ????????int id = 0; ????????try { ????????????id = this.getItem(position).getInt("id"); ????????} catch (JSONException e) { ????????????Toast.makeText(this.mContext, e.getMessage(), Toast.LENGTH_LONG); ????????} ????????return id; ????} ????/** ?????* 獲取一條數據 ?????* ?????* @param position ?????* @return ?????*/ ????public JSONObject getItem(int position) { ????????return (JSONObject) this.mDiaryDataList.opt(position); ????} ????/** ?????* 獲取視圖 ?????* ?????* @param position ?????* @param convertView ?????* @param parent ?????* @return ?????*/ ????public View getView(int position, View convertView, ViewGroup parent) ????{ ????????ZLog.v(TAG, "getView i: " + position); ????????final ViewHolder holder; ????????if (convertView == null) { ????????????convertView = LayoutInflater.from(this.mContext).inflate(R.layout.list_item_diary, null); ????????????this.mConvertView = convertView; ????????????holder = new ViewHolder(convertView); ????????????convertView.setTag(holder); ????????} else { ????????????holder = (ViewHolder) convertView.getTag(); ????????} ????????try { ????????????// 獲取當前列表單元的 JSON 日記數據 ????????????JSONObject item = this.getItem(position); ????????????ZLog.i(TAG, "getView i: "+ position +", isScrolling: "+ mIsScrolling +", mFirstPosition: "+ mFirstPosition +", mLastPosition: "+ mLastPosition); ????????????/*if (! isScrolling && (position >= mFirstPosition && position <= mLastPosition)) { ????????????????ZLog.i(TAG, "getView i: "+ position +", show images"); ????????????????this.loadImage(holder.picPhoto, holder.avatar, item); ????????????} else {*/ ????????????????ZLog.i(TAG, "getView i: "+ position +", can't show images"); ????????????// 初始化時自動加載 ????????????if (this.mLastPosition == 0) { ????????????????this.loadImage(holder.picPhoto, holder.avatar, item); ????????????????this.mPrevLastPosition = position; ????????????} else { ????????????????this.setDefaultImage(holder.picPhoto, holder.avatar, item); ????????????} ????????????????/*holder.picPhoto.setScaleType(ImageView.ScaleType.CENTER); ????????????????holder.picPhoto.setImageResource(R.drawable.default_pic); ????????????????holder.avatar.setScaleType(ImageView.ScaleType.CENTER); ????????????????holder.avatar.setImageResource(R.drawable.default_avatar); ????????????}*/ ????????????holder.nickname.setText(item.getString("nickname") +":"+ position); ????????????holder.content.setText(item.getString("content")); ????????????holder.calendarMonth.setText(ZHelper.dateFormat("MM月", item.getInt("calendarDate"))); ????????????holder.calendarDay.setText(ZHelper.dateFormat("dd", item.getInt("calendarDate"))); ????????} catch (JSONException e) { ????????????Toast.makeText(this.mContext, e.getMessage(), Toast.LENGTH_LONG); ????????} ????????return convertView; ????} ????public void setDefaultImage(ImageView picPhoto, ImageView avatar, JSONObject item) throws JSONException ????{ ????????int height = 0; ????????String picUrl = getPicUrl(item.getString("picUrl")); ????????if (mImagesHeight.containsKey(picUrl)) { ????????????height = mImagesHeight.get(picUrl); ????????} ????????int minHeight = ZUI.dp2px(this.mContext, 100); ????????if (height < minHeight) height = minHeight; ????????picPhoto.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, height)); ????????picPhoto.setScaleType(ImageView.ScaleType.CENTER); ????????picPhoto.setImageResource(R.drawable.default_pic); ????????avatar.setScaleType(ImageView.ScaleType.CENTER); ????????avatar.setImageResource(R.drawable.default_avatar); ????} ????public String getPicUrl(String pic) ????{ ????????return "http://img.ai9475.com/data/attachment/images/meitian/" + pic; ????} ????public String getAvatarUrl(String avatar) ????{ ????????return "http://img.ai9475.com/data/attachment/images/avatar/" + avatar; ????} ????/** ?????* 加載可見單元的圖片 ?????* ?????* @param picPhoto ?????* @param avatar ?????* @param item ?????* @throws JSONException ?????*/ ????public void loadImage(ImageView picPhoto, ImageView avatar, JSONObject item) throws JSONException ????{ ????????// 圖片鏈接 ????????String picUrl = getPicUrl(item.getString("picUrl")); ????????String avatarUrl = getAvatarUrl(item.getString("avatar")); ????????// 記錄異步加載的圖片標簽 ????????String picTag = "pic"+ item.getInt("calendarDate") + item.getInt("id"); ????????String avatarTag = "avatar"+ item.getInt("id"); ????????picPhoto.setTag(picTag); ????????avatar.setTag(avatarTag); ????????OnPicLoadListener mOnPicLoadListener = new OnPicLoadListener(); ????????OnAvatarLoadListener mOnAvatarLoadListener = new OnAvatarLoadListener(); ????????// 異步加載遠程日記照片或緩存 ????????Drawable picDrawable = this.mAsyncImageLoader.loadDrawable(picUrl, picTag, mOnPicLoadListener); ????????// 存在緩存則使用緩存中的圖片資源或者使用默認占位圖 ????????mOnPicLoadListener.setDrawable(picPhoto, picUrl, picTag, picDrawable); ????????// 異步加載遠程用戶頭像或加載緩存 ????????Drawable avatarDrawable = this.mAsyncImageLoader.loadDrawable(avatarUrl, avatarTag, mOnAvatarLoadListener); ????????// 存在緩存則使用緩存中的圖片資源或者使用默認占位圖 ????????mOnAvatarLoadListener.setDrawable(avatar, avatarUrl, avatarTag, avatarDrawable); ????} ????/** ?????* 當列表單元滾動到可是區域外時清除掉已記錄的圖片視圖 ?????* ?????* @param view ?????*/ ????@Override ????public void onMovedToScrapHeap(View view) { ????????/*ViewHolder holder = (ViewHolder) view.getTag(); ????????this.imageViews.remove(holder.avatar); ????????this.imageViews.remove(holder.picPhoto);*/ ????} ????private static class ViewHolder ????{ ????????public ImageView picPhoto; ????????public ImageView avatar; ????????public TextView nickname; ????????public TextView content; ????????public TextView calendarMonth; ????????public TextView calendarDay; ????????public ViewHolder(View view) ????????{ ????????????this.picPhoto = (ImageView) view.findViewById(R.id.picPhoto); ????????????this.avatar = (ImageView) view.findViewById(R.id.avatar); ????????????this.nickname = (TextView) view.findViewById(R.id.nickname); ????????????this.content = (TextView) view.findViewById(R.id.content); ????????????this.calendarMonth = (TextView) view.findViewById(R.id.calendarMonth); ????????????this.calendarDay = (TextView) view.findViewById(R.id.calendarDay); ????????} ????} ????/** ?????* 頭像圖片加載事件監聽 ?????*/ ????private class OnAvatarLoadListener extends OnImageLoadListener ????{ ????????private int mImageSource = R.drawable.default_avatar; ????????/** ?????????* 設置圖片 ?????????* ?????????* @param view ?????????* @param imageUrl ?????????* @param tag ?????????* @param drawable ?????????*/ ????????public void setDrawable(ImageView view, String imageUrl, String tag, Drawable drawable) ????????{ ????????????if (view == null) return; ????????????if (drawable != null) { ????????????????view.setScaleType(ImageView.ScaleType.CENTER_CROP); ????????????????view.setImageDrawable(drawable); ????????????} else { ????????????????view.setScaleType(ImageView.ScaleType.CENTER); ????????????????view.setImageResource(this.mImageSource); ????????????} ????????} ????} ????/** ?????* 日記照片加載事件監聽 ?????*/ ????private class OnPicLoadListener extends OnImageLoadListener ????{ ????????private int mImageSource = R.drawable.default_pic; ????????/** ?????????* 設置圖片 ?????????* ?????????* @param view ?????????* @param imageUrl ?????????* @param tag ?????????* @param drawable ?????????*/ ????????public void setDrawable(ImageView view, String imageUrl, String tag, Drawable drawable) ????????{ ????????????if (view == null) return; ????????????int height = 0; ????????????if (mImagesHeight.containsKey(imageUrl)) { ????????????????height = mImagesHeight.get(imageUrl); ????????????} ????????????if (drawable != null) { ????????????????// 定義圖片的最佳高度 ????????????????if (height == 0) { ????????????????????int minHeight = ZUI.dp2px(mContext, 100); ????????????????????int maxHeight = ZUI.dp2px(mContext, 300); ????????????????????height = (int) ((float) view.getWidth() / drawable.getMinimumWidth() * drawable.getMinimumHeight()); ????????????????????if (height > maxHeight) { ????????????????????????height = maxHeight; ????????????????????} else if (height < minHeight) { ????????????????????????height = minHeight; ????????????????????} ????????????????????mImagesHeight.put(imageUrl, height); ????????????????} ????????????????// 現將圖片完全透明 ????????????????drawable.setAlpha(0); ????????????????view.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, height)); ????????????????view.setScaleType(ImageView.ScaleType.CENTER_CROP); ????????????????view.setImageDrawable(drawable); ????????????????// 添加透明漸變動畫顯示圖片 ????????????????AlphaAnimation alphaAnim = new AlphaAnimation(0.0f, 1.0f); ????????????????alphaAnim.setDuration(1000); ????????????????view.setAnimation(alphaAnim); ????????????} else { ????????????????int minHeight = ZUI.dp2px(mContext, 100); ????????????????height = height < minHeight ? minHeight : height; ????????????????view.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, height)); ????????????????view.setScaleType(ImageView.ScaleType.CENTER); ????????????????view.setImageResource(mImageSource); ????????????} ????????} ????} ????/** ?????* 圖片的加載監聽事件 ?????*/ ????abstract private class OnImageLoadListener implements ZAsyncImageLoader.OnImageLoadListener ????{ ????????/** ?????????* 實現圖片顯示的抽象方法 ?????????* ?????????* @param view ?????????* @param tag ?????????* @param drawable ?????????*/ ????????abstract public void setDrawable(ImageView view, String imageUrl, String tag, Drawable drawable); ????????@Override ????????public void onLoaded(Drawable drawable, String imageUrl, String tag) { ????????????ImageView view = (ImageView) mDiaryListView.findViewWithTag(tag == null ? imageUrl : tag); ????????????this.setDrawable(view, imageUrl, tag, drawable); ????????} ????????@Override ????????public void onFailed(IOException e, String imageUrl, String tag) { ????????????//Toast.makeText(mContext, e.toString(), Toast.LENGTH_SHORT).show(); ????????} ????} }</string,></string,>

代碼相關的一些類方法，以及涉及到的其他方面問題的相關博文：

android 一些數據轉換方法

Android實現圖片寬度100%ImageView寬度且高度按比例自動伸縮

源碼：http://yunpan.cn/QpzhBEWCw3gDH

項目中需要修改服務端的地址，我在壓縮包中附有一些服務端發送的 JSON 數據

還可以加入 Android 文件共享群，這里全是 Android 和 JAVA 學習資料和教程：http://qun.yunpan.360.cn/38063538

轉載于:https://www.cnblogs.com/pricks/p/3921625.html

總結

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