简单使用URLConnection、HttpURLConnection和HttpClient访问网络资源

URL的openConnection方法将返回一个URLConnection，该对象表示应用程序和URL之间的通信连接。程序可以通过它的实例向该URL发送请求，读取URL引用的资源。

下面通过一个简单示例来演示：

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对象进行连接                  URL url = new URL("http://192.168.1.100:8080/myweb/hello.jsp");                 // 得到URLConnection对象                  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对象进行连接              try {                 URL url = new URL(                         "http://192.168.1.100:8080/myweb/hello.jsp?username=abc");                 // 得到HttpURLConnection对象                  HttpURLConnection connection = (HttpURLConnection) url                         .openConnection();                 // 设置为GET方式                  connection.setRequestMethod("GET");                 if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {                     // 得到响应消息                      String message = connection.getResponseMessage();                     showTextView.setText(message);                 }             } catch (Exception e) {                 e.printStackTrace();             }         }         if (v == httpClientBtn) {             try {                 // 使用ApacheHttp客户端进行连接(重要方法)                  HttpClient client = new DefaultHttpClient();                    // 如果是Get提交则创建HttpGet对象，否则创建HttpPost对象                  // POST提交的方式                  HttpPost httpPost = new HttpPost(                         "http://192.168.1.100:8080/myweb/hello.jsp");                 // 如果是Post提交可以将参数封装到集合中传递                  List dataList = new ArrayList();                 dataList.add(new BasicNameValuePair("username", "abc"));                 dataList.add(new BasicNameValuePair("pwd", "123"));                 // UrlEncodedFormEntity用于将集合转换为Entity对象                  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");                     // 获取相应消息                  HttpResponse httpResponse = client.execute(httpPost);                 // 获取消息内容                  HttpEntity entity = httpResponse.getEntity();                 // 把消息对象直接转换为字符串                  String content = EntityUtils.toString(entity);                 // 显示在TextView中                  // showTextView.setText(content);                     // 通过webview来解析网页                  webView.loadDataWithBaseURL(null, content, "text/html",                         "utf-8", null);                 // 直接根据url来进行解析                  // 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对象进行连接     URL url = new URL("http://192.168.1.100:8080/myweb/hello.jsp");     // 得到URLConnection对象     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对象进行连接    try {     URL url = new URL(       "http://192.168.1.100:8080/myweb/hello.jsp?username=abc");     // 得到HttpURLConnection对象     HttpURLConnection connection = (HttpURLConnection) url       .openConnection();     // 设置为GET方式     connection.setRequestMethod("GET");     if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {      // 得到响应消息      String message = connection.getResponseMessage();      showTextView.setText(message);     }    } catch (Exception e) {     e.printStackTrace();    }   }   if (v == httpClientBtn) {    try {     // 使用ApacheHttp客户端进行连接(重要方法)     HttpClient client = new DefaultHttpClient();     // 如果是Get提交则创建HttpGet对象，否则创建HttpPost对象     // POST提交的方式     HttpPost httpPost = new HttpPost(       "http://192.168.1.100:8080/myweb/hello.jsp");     // 如果是Post提交可以将参数封装到集合中传递     List dataList = new ArrayList();     dataList.add(new BasicNameValuePair("username", "abc"));     dataList.add(new BasicNameValuePair("pwd", "123"));     // UrlEncodedFormEntity用于将集合转换为Entity对象     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");     // 获取相应消息     HttpResponse httpResponse = client.execute(httpPost);     // 获取消息内容     HttpEntity entity = httpResponse.getEntity();     // 把消息对象直接转换为字符串     String content = EntityUtils.toString(entity);     // 显示在TextView中     // showTextView.setText(content);     // 通过webview来解析网页     webView.loadDataWithBaseURL(null, content, "text/html",       "utf-8", null);     // 直接根据url来进行解析     // webView.loadUrl(url);    } catch (ClientProtocolException e) {     e.printStackTrace();    } catch (IOException e) {     e.printStackTrace();    }   }  } }

上面使用到的url是部署在笔者本机的web应用，这里不再给出，大家可以换成自己的web应用即可。
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连接" />        <Button         android:id="@+id/test_url_main_btn_httpurlconnection"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="使用HttpURLConnection连接" />        <Button         android:id="@+id/test_url_main_btn_httpclient"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="使用Apache客户端连接" />        <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连接" />     <Button         android:id="@+id/test_url_main_btn_httpurlconnection"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="使用HttpURLConnection连接" />     <Button         android:id="@+id/test_url_main_btn_httpclient"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="使用Apache客户端连接" />     <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>

权限：
 

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

转载于:https://www.cnblogs.com/AceIsSunshineRain/p/5095114.html

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