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android ApiDemos学习1 主界面动态ListView显示

發布時間：2025/3/14 编程问答 19 豆豆

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0?Android提供了一個供開發者學習使用的示例程序。其界面如下。圖中可以看到，應用列表應為ListView，看其源碼發現，并非為簡單的ListView，而是采用動態加載的方式。

? ? ? ? ? ??

1 主界面代碼如下：

ApiDemos 1 /*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package com.example.android.apis;
18
19 import android.app.ListActivity;
20 import android.content.Intent;
21 import android.content.pm.PackageManager;
22 import android.content.pm.ResolveInfo;
23 import android.os.Bundle;
24 import android.view.View;
25 import android.widget.ListView;
26 import android.widget.SimpleAdapter;
27
28 import java.text.Collator;
29 import java.util.ArrayList;
30 import java.util.Collections;
31 import java.util.Comparator;
32 import java.util.HashMap;
33 import java.util.List;
34 import java.util.Map;
35
36 public class ApiDemos extends ListActivity {
37
38 @Override
39 public void onCreate(Bundle savedInstanceState) {
40 super.onCreate(savedInstanceState);
41
42 Intent intent = getIntent();
43 String path = intent.getStringExtra("com.example.android.apis.Path");
44
45 if (path == null) {
46 path = "";
47 }
48
49 setListAdapter(new SimpleAdapter(this, getData(path),
50 android.R.layout.simple_list_item_1, new String[] { "title" },
51 new int[] { android.R.id.text1 }));
52 getListView().setTextFilterEnabled(true);
53 }
54
55 protected List getData(String prefix) {
56 List<Map> myData = new ArrayList<Map>();
57
58 Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
59 mainIntent.addCategory(Intent.CATEGORY_SAMPLE_CODE);
60
61 PackageManager pm = getPackageManager();
62 List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);
63
64 if (null == list)
65 return myData;
66
67 String[] prefixPath;
68
69 if (prefix.equals("")) {
70 prefixPath = null;
71 } else {
72 prefixPath = prefix.split("/");
73 }
74
75 int len = list.size();
76
77 Map<String, Boolean> entries = new HashMap<String, Boolean>();
78
79 for (int i = 0; i < len; i++) {
80 ResolveInfo info = list.get(i);
81 CharSequence labelSeq = info.loadLabel(pm);
82 String label = labelSeq != null
83 ? labelSeq.toString()
84 : info.activityInfo.name;
85
86 if (prefix.length() == 0 || label.startsWith(prefix)) {
87
88 String[] labelPath = label.split("/");
89
90 String nextLabel = prefixPath == null ? labelPath[0] : labelPath[prefixPath.length];
91
92 if ((prefixPath != null ? prefixPath.length : 0) == labelPath.length - 1) {
93 addItem(myData, nextLabel, activityIntent(
94 info.activityInfo.applicationInfo.packageName,
95 info.activityInfo.name));
96 } else {
97 if (entries.get(nextLabel) == null) {
98 addItem(myData, nextLabel, browseIntent(prefix.equals("") ? nextLabel : prefix + "/" + nextLabel));
99 entries.put(nextLabel, true);
100 }
101 }
102 }
103 }
104
105 Collections.sort(myData, sDisplayNameComparator);
106
107 return myData;
108 }
109
110 private final static Comparator<Map> sDisplayNameComparator = new Comparator<Map>() {
111 private final Collator collator = Collator.getInstance();
112
113 public int compare(Map map1, Map map2) {
114 return collator.compare(map1.get("title"), map2.get("title"));
115 }
116 };
117
118 protected Intent activityIntent(String pkg, String componentName) {
119 Intent result = new Intent();
120 result.setClassName(pkg, componentName);
121 return result;
122 }
123
124 protected Intent browseIntent(String path) {
125 Intent result = new Intent();
126 result.setClass(this, ApiDemos.class);
127 result.putExtra("com.example.android.apis.Path", path);
128 return result;
129 }
130
131 protected void addItem(List<Map> data, String name, Intent intent) {
132 Map<String, Object> temp = new HashMap<String, Object>();
133 temp.put("title", name);
134 temp.put("intent", intent);
135 data.add(temp);
136 }
137
138 @Override
139 protected void onListItemClick(ListView l, View v, int position, long id) {
140 Map map = (Map) l.getItemAtPosition(position);
141
142 Intent intent = (Intent) map.get("intent");
143 startActivity(intent);
144 }
145
146 }

?下面為部分配置文件代碼：

Manifest.xml <?xml version="1.0" encoding="utf-8"?>



<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.apis">

<uses-permission android:name="android.permission.READ_CONTACTS" />
<uses-permission android:name="android.permission.WRITE_CONTACTS" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.SET_WALLPAPER" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.SEND_SMS" />
<uses-permission android:name="android.permission.RECEIVE_SMS" />
<uses-permission android:name="android.permission.NFC" />


<uses-permission android:name="android.permission.RECORD_AUDIO" />


<uses-permission android:name="android.permission.CAMERA" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" android:required="false" />

<application android:name="ApiDemosApplication"
android:label="@string/activity_sample_code"
android:icon="@drawable/app_sample_code" >


<uses-library android:name="com.example.will.never.exist" android:required="false" />

<activity android:name="ApiDemos">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.DEFAULT" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>







<activity android:name=".app.HelloWorld" android:label="@string/activity_hello_world">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.DialogActivity"
android:label="@string/activity_dialog"
android:theme="@android:style/Theme.Dialog">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.CustomDialogActivity"
android:label="@string/activity_custom_dialog"
android:theme="@style/Theme.CustomDialog">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.SAMPLE_CODE" />
</intent-filter>
</activity>

<activity android:name=".app.QuickContactsDemo"
android:label="@string/quick_contacts_demo">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.SAMPLE_CODE" />
</intent-filter>
</activity>

</application>

<instrumentation android:name=".app.LocalSampleInstrumentation"
android:targetPackage="com.example.android.apis"
android:label="Local Sample" />

</manifest>

2 分析

　　其想法主要分為以下幾步：

　　1) 給想要顯示在列表中的Activity分類

　　2) 然后從xml中根據分類標簽搜索出來

　　3) 將結果加載到List<Map>中

　　4) 據此list生成ListView并顯示

　　1) 想達到分類的效果，我們可以在Manifest.xml中對Activity做如下配置，稍后可根據category值進行過濾搜索。在自己的應用中，我們可以自定義category值。

　　2)?根據category值查詢出想顯示的activity對應的ResolveInfo值列表。ResolveInfo對象包含Manifest.xml中對應Activity節點的所有信息，稍后可以根據這些信息對其進行加載。　

Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
mainIntent.addCategory(Intent.CATEGORY_SAMPLE_CODE);

PackageManager pm = getPackageManager();
List<ResolveInfo> list = pm.queryIntentActivities(mainIntent, 0);

?　3) 根據查詢出的activity的ResolveInfo list,生成List<Map>，其中Map包含title和intent　

//10 得到父節點級別數組
String[] prefixPath;

if (prefix.equals("")) {
prefixPath = null;
} else {
prefixPath = prefix.split("/");
}

int len = list.size();

Map<String, Boolean> entries = new HashMap<String, Boolean>();

//11 對過濾得到的ResolveInfo列表進行遍歷
for (int i = 0; i < len; i++) {

//111 得到ResolveInfo對象
ResolveInfo info = list.get(i);
CharSequence labelSeq = info.loadLabel(pm);

//112 根據ResolveInfo對象得到Activity對應的label信息，如App/Activity/Hello World
String label = labelSeq != null
? labelSeq.toString()
: info.activityInfo.name;

//113 判斷是否有子節點存在
if (prefix.length() == 0 || label.startsWith(prefix)) {

//114 得到字節點的層級數組，如{"App","Activity","Hello World"}
String[] labelPath = label.split("/");

//115 得到應顯示層級的標簽，如 App
String nextLabel = prefixPath == null ? labelPath[0] : labelPath[prefixPath.length];

//116 當前節點無子節點，且不為第一個級別，將對應Activity信息和標簽信息組裝成intent,添加至List<Map>
if ((prefixPath != null ? prefixPath.length : 0) == labelPath.length - 1) {
addItem(myData, nextLabel, activityIntent(
info.activityInfo.applicationInfo.packageName,
info.activityInfo.name));
} else {//116 當前節點有子節點或為第一級節點
//117 判斷是否在父節點數組中
if (entries.get(nextLabel) == null) {
//118 將當前activity和節點路徑信息一起組裝成intent，添加至List<Map>
addItem(myData, nextLabel, browseIntent(prefix.equals("") ? nextLabel : prefix + "/" + nextLabel));
//119 將此節點路徑加到父節點數組中
entries.put(nextLabel, true);
}
}
}
}

　　4) 根據List<Map>生成ListView　　

setListAdapter(new SimpleAdapter(this, getData(path),
android.R.layout.simple_list_item_1, new String[] { "title" },
new int[] { android.R.id.text1 }));
getListView().setTextFilterEnabled(true);

轉載于:https://www.cnblogs.com/myparamita/archive/2011/10/31/2230777.html

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