使用HttpURLConnection发送post和get请求

    package test;  
     
    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 HttpURLConnectionTest {  
     
         public static final String GET_URL = "http://localhost:8080/welcome1";  
     
         public static final String POST_URL = "http://localhost:8080/welcome1";  
     
         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，这里URL是一个http，因此实际返回的是HttpURLConnection  
             HttpURLConnection connection = (HttpURLConnection) getUrl  
                     .openConnection();  
             // 进行连接，但是实际上get request要在下一句的connection.getInputStream()函数中才会真正发到  
             // 服务器  
             connection.connect();  
             // 取得输入流，并使用Reader读取  
             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();  
             // Output to the connection. Default is  
             // false, set to true because post  
             // method must write something to the  
             // connection  
             // 设置是否向connection输出，因为这个是post请求，参数要放在  
             // http正文内，因此需要设为true  
             connection.setDoOutput(true);  
             // Read from the connection. Default is true.  
             connection.setDoInput(true);  
             // Set the post method. Default is GET  
             connection.setRequestMethod("POST");  
             // Post cannot use caches  
             // Post 请求不能使用缓存  
             connection.setUseCaches(false);  
             // This method takes effects to  
             // every instances of this class.  
             // URLConnection.setFollowRedirects是static函数，作用于所有的URLConnection对象。  
             // connection.setFollowRedirects(true);  
     
             // This methods only  
             // takes effacts to this  
             // instance.  
             // URLConnection.setInstanceFollowRedirects是成员函数，仅作用于当前函数  
             connection.setInstanceFollowRedirects(true);  
             // Set the content type to urlencoded,  
             // because we will write  
             // some URL-encoded content to the  
             // connection. Settings above must be set before connect!  
             // 配置本次连接的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connect。  
             connection.connect();  
             DataOutputStream out = new DataOutputStream(connection  
                     .getOutputStream());  
             // The URL-encoded contend  
             // 正文，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();  
         }  
     
         /**  
          * @param args  
          */  
         public static void main(String[] args) {  
             
             try {  
                 readContentFromGet();  
                 readContentFromPost();  
             } catch (IOException e) {  
             
                 e.printStackTrace();  
             }  
         }  
    }