Apache HttpComponents Client 4.0快速入门/升级-1.GET方法访问网页（转）

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转载自邬贼博客，原文地址：http://blog.csdn.net/inkfish/archive/2009/11/02/4757380.aspx
Apache HttpComponents Client 4.0已经发布多时，httpclient项目从commons子项目挪到了HttpComponents子项目下，httpclient3.1和httpcilent4.0无法做到代码向后兼容，升级比较麻烦。我在做项目之余找时间研究了一下，写了一套3.1与4.0对比的代码，不求面面俱到，但求简单易懂。如果代码用到真实项目中，还需要考虑诸如代理、Header、异常处理之类的问题。
Http GET方法得到www.g.cn的源码：
import java.io.IOException;   
import org.apache.commons.httpclient.HttpException;   
import org.apache.commons.httpclient.HttpStatus;   
import org.apache.commons.httpclient.methods.GetMethod;   
import org.apache.http.client.ClientProtocolException;   
import org.apache.http.client.methods.HttpGet;   
import org.apache.http.impl.client.BasicResponseHandler;   
import org.apache.http.impl.client.DefaultHttpClient;   
public class GetSample {   
/**  
* @param args  
* @throws IOException  
* @throws HttpException  
*/  
public static void main(String[] args) throws HttpException, IOException {   
String url = "http://www.g.cn/";   
System.out.println(url);   
System.out.println("Visit google using Apache commons-httpclient 3.1：");   
System.out.println(get3(url));   
System.out.println("Visit google using Apache HttpComponents Client 4.0：");   
System.out.println(get4(url));   
}   
/** 使用Apache commons-httpclient 3.1，GET方法访问网页 */  
public static String get3(String url) throws HttpException, IOException {   
org.apache.commons.httpclient.HttpClient httpClient = new org.apache.commons.httpclient.HttpClient();   
GetMethod getMethod = new GetMethod(url);   
try {   
if (httpClient.executeMethod(getMethod) != HttpStatus.SC_OK) {   
System.err.println("Method failed: " + getMethod.getStatusLine());   
}   
return getMethod.getResponseBodyAsString();   
} finally {   
getMethod.releaseConnection();   
}   
}   
/** 使用Apache HttpComponents Client 4.0，GET方法访问网页 */  
public static String get4(String url) throws ClientProtocolException, IOException {   
org.apache.http.client.HttpClient client = new DefaultHttpClient();   
HttpGet httpget = new HttpGet(url);   
try {   
return client.execute(httpget, new BasicResponseHandler());   
} finally {   
client.getConnectionManager().shutdown();   
}   
}   
}  

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/inkfish/archive/2009/11/02/4757380.aspx