HttpClients下载与入门

Http协议的重要性相信不用我多说了，HttpClient相比传统JDK自带的URLConnection，增加了易用性和灵活性（具体区别，日后我们再讨论），它不仅是客户端发送Http请求变得容易，而且也方便了开发人员测试接口（基于Http协议的），即提高了开发的效率，也方便提高代码的健壮性。因此熟练掌握HttpClient是很重要的必修内容，掌握HttpClient后，相信对于Http协议的了解会更加深入。

 

你可以从官方获取最新版本：http://hc.apache.org/index.html。也可以从这里获取官方使用入门示例。
以下示例，输出所有头内容，和页面返回的内容。

import  java.io.ByteArrayOutputStream;
import  java.io.InputStream;
import  java.util.ArrayList;
import  java.util.List;
import  org.apache.http.Header;
import  org.apache.http.HttpEntity;
import  org.apache.http.NameValuePair;
import  org.apache.http.client.entity.UrlEncodedFormEntity;
import  org.apache.http.client.methods.CloseableHttpResponse;
import  org.apache.http.client.methods.HttpGet;
import  org.apache.http.client.methods.HttpPost;
import  org.apache.http.impl.client.CloseableHttpClient;
import  org.apache.http.impl.client.HttpClients;
import  org.apache.http.message.BasicNameValuePair;
public  class  QuickStart {
 public  static  void  main(String[] args) {
  try  {
   CloseableHttpClient httpclient = HttpClients.createDefault();
   HttpGet httpGet =  new  HttpGet( "http://javacui.com" );
   CloseableHttpResponse response1 = httpclient.execute(httpGet);
   try  {
       System.out.println(response1.getStatusLine());  // 读取状态信息

       Header[] hd = response1.getAllHeaders();  // 所有头信息
       for (Header h : hd){
        System.out.println(h.getName() +  "："  + h.getValue());
       }

       HttpEntity entity1 = response1.getEntity();
       System.out.println(EntityUtils.toString(entity1));
   }  finally  {
       response1.close();
   }
   HttpPost httpPost =  new  HttpPost( "http://javacui.com" );
   List <NameValuePair> paras =  new  ArrayList <NameValuePair>();  // 设置表单参数
   paras.add( new  BasicNameValuePair( "username" ,  "name" ));
   paras.add( new  BasicNameValuePair( "password" ,  "pass" ));
   httpPost.setEntity( new  UrlEncodedFormEntity(paras));
   CloseableHttpResponse response2 = httpclient.execute(httpPost);
   try  {
    System.out.println(response1.getStatusLine());  // 读取状态信息

       Header[] hd = response1.getAllHeaders();  // 所有头信息
       for (Header h : hd){
        System.out.println(h.getName() +  "："  + h.getValue());
       }

       HttpEntity entity1 = response1.getEntity();
       System.out.println(EntityUtils.toString(entity1));
   }  finally  {
       response2.close();
   }
  }  catch  (Exception e) {
   e.printStackTrace();
  }
 }

 /**
  * 读取流
  */
 public  static  byte [] readStream(InputStream inStream)  throws  Exception {
  ByteArrayOutputStream outSteam =  new  ByteArrayOutputStream();
  byte [] buffer =  new  byte [ 1024 ];
  int  len = - 1 ;
  while  ((len = inStream.read(buffer)) != - 1 ) {
   outSteam.write(buffer,  0 , len);
  }
  outSteam.close();
  inStream.close();
  return  outSteam.toByteArray();
 }
}
// 结束

GET和POST请求都输出了获取到的服务器内容，POST请求设置了请求的表单参数。

参考资料：

jquery ajax 设置json类型的返回串问题  http://www.itmmd.com/201504/694.html

java jsp实现万年历 + 日程管理，已经设计好u  http://www.itmmd.com/201504/693.html

jquery 动态添加和删除 ul li列表  http://www.itmmd.com/201504/692.html

更多信息请访问：萌萌的it人