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：
 

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();
补充：移动开发 , Android ,

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