演示实例：AServlet发送一个Student对象到BServlet

#### 1.AServlet部分

首先造一个学生stu，然后通过fastjson的`toJSONString`方法把对象转换成字符串，再通过MyHttpUtils的`sendPost`方法把数据发送到BServlet

核心部分是`MyHttpUtils`类，还用到了`fastjson.jar`包

```java

@WebServlet("/AServet")

public class AServet extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding("utf-8");

response.setContentType("text/html;charset=utf-8");

Stu stu = new Stu();

stu.setAge(12);

stu.setName("ergou");

stu.setSex(1);

String str = JSON.toJSONString(stu);//将java对象转换为json字符串

response.getWriter().append("将发送请求给B");

String ret = MyHttpUtils.sendPost("http://localhost:8080/HttpServletTest/BServet", "data="+str);

System.out.println("来自BServlet的返回值：" + ret);

}

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doPost(request, response);

}

}

```

##### MyHttpUtils类

```java

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.io.PrintWriter;

import java.net.URL;

import java.net.URLConnection;

public class MyHttpUtils {

/**

* 向指定 URL 发送POST方法的请求

*

* @param url

*            发送请求的 URL

* @param param

*            请求参数，请求参数应该是 name1=value1&name2=value2 的形式。

* @return 所代表远程资源的响应结果

*/

public static String sendPost(String url, String param) {

PrintWriter out = null;

BufferedReader in = null;

String result = "";

try {

URL realUrl = new URL(url);

// 打开和URL之间的连接

URLConnection conn = realUrl.openConnection();

// 设置通用的请求属性

conn.setRequestProperty("accept", "*/*");

conn.setRequestProperty("connection", "Keep-Alive");

conn.setRequestProperty("user-agent",

"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1;SV1)");

// 发送POST请求必须设置如下两行

conn.setDoOutput(true);

conn.setDoInput(true);

// 获取URLConnection对象对应的输出流

out = new PrintWriter(conn.getOutputStream());

// 发送请求参数

out.print(param);

// flush输出流的缓冲

out.flush();

// 定义BufferedReader输入流来读取URL的响应

in = new BufferedReader(

new InputStreamReader(conn.getInputStream()));

String line;

while ((line = in.readLine()) != null) {

result += line;

}

} catch (Exception e) {

System.out.println("发送 POST 请求出现异常！"+e);

e.printStackTrace();

}

//使用finally块来关闭输出流、输入流

finally{

try{

if(out!=null){

out.close();

}

if(in!=null){

in.close();

}

}

catch(IOException ex){

ex.printStackTrace();

}

}

return result;

}

}

```

#### 2.BServlet部分

接收来自AServlet的数据String，然后通过fastjson包的parseObject方法把字符串转成Stu对象，再取出需要的值

```java

/**

* Servlet implementation class AServet

*/

@WebServlet("/BServet")

public class BServet extends HttpServlet {

private static final long serialVersionUID = 1L;

/**

* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)

*/

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

request.setCharacterEncoding("utf-8");

response.setContentType("text/html;charset=utf-8");

String data = request.getParameter("data");

if(data == null) {

response.getWriter().append("data为空");

return;

}

Stu stu = JSON.parseObject(data, Stu.class);

System.out.println();

System.out.println("收到请求，学生是: " + stu.getName());

response.getWriter().append("收到请求，学生是: " + stu.getName());

}

/**

* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)

*/

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

doPost(request, response);

}

}

```