java 发送http请求

package com.service; 

import java.io.BufferedReader; 
import java.io.DataOutputStream; 
import java.io.IOException; 
import java.io.InputStreamReader; 
import java.net.HttpURLConnection; 
import java.net.URL; 
import java.net.URLEncoder; 

public class HttpInvoker { 
        public static final String GET_URL = " http://localhost:8080/demo/  "; 
        public static final String POST_URL = " http://localhost:8080/demo/  "; 

        public static void readContentFromGet() throws IOException { 
               // 拼凑get请求的URL字串，使用URLEncoder.encode对特殊和不可见字符进行编码 
               String getURL = GET_URL + " ?username= " 
                               + URLEncoder.encode("fat man", " utf-8 "); 
               URL getUrl = new URL(getURL); 
               // 根据拼凑的URL，打开连接，URL.openConnection()函数会根据 URL的类型，返回不同的URLConnection子类的对象，在这里我们的URL是一个http，因此它实际上返回的是HttpURLConnection 
               HttpURLConnection connection = (HttpURLConnection) getUrl.openConnection(); 
               // 建立与服务器的连接，并未发送数据 
               connection.connect(); 
               // 发送数据到服务器并使用Reader读取返回的数据 
               BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); 
               System.out.println(" ============================= "); 
               System.out.println(" Contents of get request "); 
               System.out.println(" ============================= "); 
               String lines; 
               while ((lines = reader.readLine()) != null) { 
                       System.out.println(lines); 
               } 
               reader.close(); 
               // 断开连接 
               connection.disconnect(); 
               System.out.println(" ============================= "); 
               System.out.println(" Contents of get request ends "); 
               System.out.println(" ============================= "); 
        } 
        public static void readContentFromPost() throws IOException { 
               // Post请求的url，与get不同的是不需要带参数 
               URL postUrl = new URL(POST_URL); 
               // 打开连接 
               HttpURLConnection connection = (HttpURLConnection) postUrl.openConnection(); 
               //打开读写属性，默认均为false 
               connection.setDoOutput(true);                 
　　　　　　　 connection.setDoInput(true); 
               // 设置请求方式，默认为GET 
               connection.setRequestMethod(" POST "); 
               // Post 请求不能使用缓存 
               connection.setUseCaches(false); 
               // URLConnection.setFollowRedirects是static 函数，作用于所有的URLConnection对象。 
               // connection.setFollowRedirects(true); 
               //URLConnection.setInstanceFollowRedirects 是成员函数，仅作用于当前函数 
               connection.setInstanceFollowRedirects(true); 
               // 配置连接的Content-type，配置为application/x- www-form-urlencoded的意思是正文是urlencoded编码过的form参数，下面我们可以看到我们对正文内容使用URLEncoder.encode进行编码 
               connection.setRequestProperty(" Content-Type ", 
                               " application/x-www-form-urlencoded "); 
               // 连接，从postUrl.openConnection()至此的配置必须要在 connect之前完成， 
               // 要注意的是connection.getOutputStream()会隐含的进行调用 connect()，所以这里可以省略 
               //connection.connect(); 
               DataOutputStream out = new DataOutputStream(connection.getOutputStream()); 
               //正文内容其实跟get的URL中‘?‘后的参数字符串一致 
               String content = " firstname= "+URLEncoder.encode(" 一个大肥人 ", " utf-8 "); 
               // DataOutputStream.writeBytes将字符串中的16位的 unicode字符以8位的字符形式写道流里面 
               out.writeBytes(content); 
               out.flush(); 
               out.close(); // flush and close 
               BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); 
               String line; 
               System.out.println(" ============================= "); 
               System.out.println(" Contents of post request "); 
               System.out.println(" ============================= "); 
               while ((line = reader.readLine()) != null) { 
                       System.out.println(line); 
               } 
               System.out.println(" ============================= "); 
               System.out.println(" Contents of post request ends "); 
               System.out.println(" ============================= "); 
               reader.close(); 
               //connection.disconnect(); 
        } 
        public static void main(String[] args) { 
               // TODO Auto-generated method stub 
               try { 
                       readContentFromGet(); 
                       readContentFromPost(); 
               } catch (IOException e) { 
                       // TODO Auto-generated catch block 
                       e.printStackTrace(); 
               } 
        } 
}