URL的openConnection方法將返回一個URLConnection，該對象表示應用程序和URL之間的通信連接。程序可以通過它的實例向該URL發(fā)送請求，讀取URL引用的資源。

下面通過一個簡單示例來演示：

Activity：
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package com.home.urlconnection; ?? import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLConnection; import java.util.ArrayList; import java.util.List; ?? import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; import org.apache.http.util.EntityUtils; ?? import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.webkit.WebView; import android.widget.Button; import android.widget.TextView; ?? public class MainActivity extends Activity implements OnClickListener { ????private Button urlConnectionBtn; ????private Button httpUrlConnectionBtn; ????private Button httpClientBtn; ????private TextView showTextView; ????private WebView webView; ?? ????@Override ????protected void onCreate(Bundle savedInstanceState) { ????????super.onCreate(savedInstanceState); ????????setContentView(R.layout.activity_main); ????????init(); ????} ?? ????private void init() { ????????urlConnectionBtn = (Button) findViewById(R.id.test_url_main_btn_urlconnection); ????????httpUrlConnectionBtn = (Button) findViewById(R.id.test_url_main_btn_httpurlconnection); ????????httpClientBtn = (Button) findViewById(R.id.test_url_main_btn_httpclient); ????????showTextView = (TextView) findViewById(R.id.test_url_main_tv_show); ????????webView = (WebView) findViewById(R.id.test_url_main_wv); ????????urlConnectionBtn.setOnClickListener(this); ????????httpUrlConnectionBtn.setOnClickListener(this); ????????httpClientBtn.setOnClickListener(this); ????} ?? ????@Override ????public void onClick(View v) { ????????if (v == urlConnectionBtn) { ????????????try { ????????????????// 直接使用URLConnection對象進行連接? ????????????????URL url = new URL("http://192.168.1.100:8080/myweb/hello.jsp"); ????????????????// 得到URLConnection對象? ????????????????URLConnection connection = url.openConnection(); ????????????????InputStream is = connection.getInputStream(); ????????????????byte[] bs = new byte[1024]; ????????????????int len = 0; ????????????????StringBuffer sb = new StringBuffer(); ????????????????while ((len = is.read(bs)) != -1) { ????????????????????String str = new String(bs, 0, len); ????????????????????sb.append(str); ????????????????} ????????????????showTextView.setText(sb.toString()); ????????????} catch (Exception e) { ????????????????e.printStackTrace(); ????????????} ????????} ????????if (v == httpUrlConnectionBtn) { ????????????// 直接使用HttpURLConnection對象進行連接? ????????????try { ????????????????URL url = new URL( ????????????????????????"http://192.168.1.100:8080/myweb/hello.jsp?username=abc"); ????????????????// 得到HttpURLConnection對象? ????????????????HttpURLConnection connection = (HttpURLConnection) url ????????????????????????.openConnection(); ????????????????// 設置為GET方式? ????????????????connection.setRequestMethod("GET"); ????????????????if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) { ????????????????????// 得到響應消息? ????????????????????String message = connection.getResponseMessage(); ????????????????????showTextView.setText(message); ????????????????} ????????????} catch (Exception e) { ????????????????e.printStackTrace(); ????????????} ????????} ????????if (v == httpClientBtn) { ????????????try { ????????????????// 使用ApacheHttp客戶端進行連接(重要方法)? ????????????????HttpClient client = new DefaultHttpClient(); ?? ????????????????// 如果是Get提交則創(chuàng)建HttpGet對象，否則創(chuàng)建HttpPost對象? ????????????????// POST提交的方式? ????????????????HttpPost httpPost = new HttpPost( ????????????????????????"http://192.168.1.100:8080/myweb/hello.jsp"); ????????????????// 如果是Post提交可以將參數封裝到集合中傳遞? ????????????????List dataList = new ArrayList(); ????????????????dataList.add(new BasicNameValuePair("username", "abc")); ????????????????dataList.add(new BasicNameValuePair("pwd", "123")); ????????????????// UrlEncodedFormEntity用于將集合轉換為Entity對象? ????????????????httpPost.setEntity(new UrlEncodedFormEntity(dataList)); ?? ????????????????// GET提交的方式? ????????????????// HttpGet httpGet = new? ????????????????// HttpGet("http://192.168.1.100:8080/myweb/hello.jsp?username=abc&pwd=321");? ?? ????????????????// 獲取相應消息? ????????????????HttpResponse httpResponse = client.execute(httpPost); ????????????????// 獲取消息內容? ????????????????HttpEntity entity = httpResponse.getEntity(); ????????????????// 把消息對象直接轉換為字符串? ????????????????String content = EntityUtils.toString(entity); ????????????????// 顯示在TextView中? ????????????????// showTextView.setText(content);? ?? ????????????????// 通過webview來解析網頁? ????????????????webView.loadDataWithBaseURL(null, content, "text/html", ????????????????????????"utf-8", null); ????????????????// 直接根據url來進行解析? ????????????????// webView.loadUrl(url);? ????????????} catch (ClientProtocolException e) { ????????????????e.printStackTrace(); ????????????} catch (IOException e) { ????????????????e.printStackTrace(); ????????????} ????????} ????} ?? } package com.home.urlconnection; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import java.net.URLConnection; import java.util.ArrayList; import java.util.List; import org.apache.http.HttpEntity; import org.apache.http.HttpResponse; import org.apache.http.client.ClientProtocolException; import org.apache.http.client.HttpClient; import org.apache.http.client.entity.UrlEncodedFormEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicNameValuePair; import org.apache.http.util.EntityUtils; import android.app.Activity; import android.os.Bundle; import android.view.View; import android.view.View.OnClickListener; import android.webkit.WebView; import android.widget.Button; import android.widget.TextView; public class MainActivity extends Activity implements OnClickListener { ?private Button urlConnectionBtn; ?private Button httpUrlConnectionBtn; ?private Button httpClientBtn; ?private TextView showTextView; ?private WebView webView; ?@Override ?protected void onCreate(Bundle savedInstanceState) { ??super.onCreate(savedInstanceState); ??setContentView(R.layout.activity_main); ??init(); ?} ?private void init() { ??urlConnectionBtn = (Button) findViewById(R.id.test_url_main_btn_urlconnection); ??httpUrlConnectionBtn = (Button) findViewById(R.id.test_url_main_btn_httpurlconnection); ??httpClientBtn = (Button) findViewById(R.id.test_url_main_btn_httpclient); ??showTextView = (TextView) findViewById(R.id.test_url_main_tv_show); ??webView = (WebView) findViewById(R.id.test_url_main_wv); ??urlConnectionBtn.setOnClickListener(this); ??httpUrlConnectionBtn.setOnClickListener(this); ??httpClientBtn.setOnClickListener(this); ?} ?@Override ?public void onClick(View v) { ??if (v == urlConnectionBtn) { ???try { ????// 直接使用URLConnection對象進行連接 ????URL url = new URL("http://192.168.1.100:8080/myweb/hello.jsp"); ????// 得到URLConnection對象 ????URLConnection connection = url.openConnection(); ????InputStream is = connection.getInputStream(); ????byte[] bs = new byte[1024]; ????int len = 0; ????StringBuffer sb = new StringBuffer(); ????while ((len = is.read(bs)) != -1) { ?????String str = new String(bs, 0, len); ?????sb.append(str); ????} ????showTextView.setText(sb.toString()); ???} catch (Exception e) { ????e.printStackTrace(); ???} ??} ??if (v == httpUrlConnectionBtn) { ???// 直接使用HttpURLConnection對象進行連接 ???try { ????URL url = new URL( ??????"http://192.168.1.100:8080/myweb/hello.jsp?username=abc"); ????// 得到HttpURLConnection對象 ????HttpURLConnection connection = (HttpURLConnection) url ??????.openConnection(); ????// 設置為GET方式 ????connection.setRequestMethod("GET"); ????if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) { ?????// 得到響應消息 ?????String message = connection.getResponseMessage(); ?????showTextView.setText(message); ????} ???} catch (Exception e) { ????e.printStackTrace(); ???} ??} ??if (v == httpClientBtn) { ???try { ????// 使用ApacheHttp客戶端進行連接(重要方法) ????HttpClient client = new DefaultHttpClient(); ????// 如果是Get提交則創(chuàng)建HttpGet對象，否則創(chuàng)建HttpPost對象 ????// POST提交的方式 ????HttpPost httpPost = new HttpPost( ??????"http://192.168.1.100:8080/myweb/hello.jsp"); ????// 如果是Post提交可以將參數封裝到集合中傳遞 ????List dataList = new ArrayList(); ????dataList.add(new BasicNameValuePair("username", "abc")); ????dataList.add(new BasicNameValuePair("pwd", "123")); ????// UrlEncodedFormEntity用于將集合轉換為Entity對象 ????httpPost.setEntity(new UrlEncodedFormEntity(dataList)); ????// GET提交的方式 ????// HttpGet httpGet = new ????// HttpGet("http://192.168.1.100:8080/myweb/hello.jsp?username=abc&pwd=321"); ????// 獲取相應消息 ????HttpResponse httpResponse = client.execute(httpPost); ????// 獲取消息內容 ????HttpEntity entity = httpResponse.getEntity(); ????// 把消息對象直接轉換為字符串 ????String content = EntityUtils.toString(entity); ????// 顯示在TextView中 ????// showTextView.setText(content); ????// 通過webview來解析網頁 ????webView.loadDataWithBaseURL(null, content, "text/html", ??????"utf-8", null); ????// 直接根據url來進行解析 ????// webView.loadUrl(url); ???} catch (ClientProtocolException e) { ????e.printStackTrace(); ???} catch (IOException e) { ????e.printStackTrace(); ???} ??} ?} }

上面使用到的url是部署在筆者本機的web應用，這里不再給出，大家可以換成自己的web應用即可。
布局XML：
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<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" ????android:layout_width="match_parent" ????android:layout_height="match_parent" ????android:orientation="vertical" > ?? ????<Button ????????android:id="@+id/test_url_main_btn_urlconnection" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" ????????android:text="使用URLConnection連接" /> ?? ????<Button ????????android:id="@+id/test_url_main_btn_httpurlconnection" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" ????????android:text="使用HttpURLConnection連接" /> ?? ????<Button ????????android:id="@+id/test_url_main_btn_httpclient" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" ????????android:text="使用Apache客戶端連接" /> ?? ????<TextView ????????android:id="@+id/test_url_main_tv_show" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" /> ?? ????<WebView ????????android:id="@+id/test_url_main_wv" ????????android:layout_width="match_parent" ????????android:layout_height="match_parent" /> ?? </LinearLayout> <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" ????android:layout_width="match_parent" ????android:layout_height="match_parent" ????android:orientation="vertical" > ????<Button ????????android:id="@+id/test_url_main_btn_urlconnection" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" ????????android:text="使用URLConnection連接" /> ????<Button ????????android:id="@+id/test_url_main_btn_httpurlconnection" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" ????????android:text="使用HttpURLConnection連接" /> ????<Button ????????android:id="@+id/test_url_main_btn_httpclient" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" ????????android:text="使用Apache客戶端連接" /> ????<TextView ????????android:id="@+id/test_url_main_tv_show" ????????android:layout_width="wrap_content" ????????android:layout_height="wrap_content" /> ????<WebView ????????android:id="@+id/test_url_main_wv" ????????android:layout_width="match_parent" ????????android:layout_height="match_parent" /> </LinearLayout>

權限：
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<uses-permission android:name="android.permission.INTERNET" /> ?<uses-permission android:name="android.permission.INTERNET" />

轉載于:https://www.cnblogs.com/AceIsSunshineRain/p/5095114.html

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