簡單使用URLConnection、HttpURLConnection和HttpClient訪問網路資源

URL的openConnection方法將返回一個URLConnection，該對象表示應用程式和URL之間的通訊串連。程式可以通過它的執行個體向該URL發送請求，讀取URL引用的資源。

下面通過一個簡單樣本來示範：

Activity：
 

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對象進行串連                  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對象進行串連              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();                 // 設定為GET方式                  connection.setRequestMethod("GET");                 if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {                     // 得到響應訊息                      String message = connection.getResponseMessage();                     showTextView.setText(message);                 }             } catch (Exception e) {                 e.printStackTrace();             }         }         if (v == httpClientBtn) {             try {                 // 使用ApacheHttp用戶端進行串連(重要方法)                  HttpClient client = new DefaultHttpClient();                  // 如果是Get提交則建立HttpGet對象，否則建立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用於將集合轉換為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");                   // 擷取相應訊息                  HttpResponse httpResponse = client.execute(httpPost);                 // 擷取訊息內容                  HttpEntity entity = httpResponse.getEntity();                 // 把訊息對象直接轉換為字串                  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對象進行串連    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對象進行串連   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();    // 設定為GET方式    connection.setRequestMethod("GET");    if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {     // 得到響應訊息     String message = connection.getResponseMessage();     showTextView.setText(message);    }   } catch (Exception e) {    e.printStackTrace();   }  }  if (v == httpClientBtn) {   try {    // 使用ApacheHttp用戶端進行串連(重要方法)    HttpClient client = new DefaultHttpClient();    // 如果是Get提交則建立HttpGet對象，否則建立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用於將集合轉換為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");    // 擷取相應訊息    HttpResponse httpResponse = client.execute(httpPost);    // 擷取訊息內容    HttpEntity entity = httpResponse.getEntity();    // 把訊息對象直接轉換為字串    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是部署在筆者原生web應用，這裡不再給出，大家可以換成自己的web應用即可。
布局XML：
 

<?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串連" />      <Button         android:id="@+id/test_url_main_btn_httpurlconnection"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="使用HttpURLConnection串連" />      <Button         android:id="@+id/test_url_main_btn_httpclient"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="使用Apache用戶端串連" />      <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串連" />    <Button        android:id="@+id/test_url_main_btn_httpurlconnection"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="使用HttpURLConnection串連" />    <Button        android:id="@+id/test_url_main_btn_httpclient"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="使用Apache用戶端串連" />    <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>

許可權：
 

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