演示實例：AServlet發送一個Student對象到BServlet

#### 1.AServlet部分

首先造一個學生stu，然后通過fastjson的`toJSONString`方法把對象轉換成字符串，再通過MyHttpUtils的`sendPost`方法把數據發送到BServlet

核心部分是`MyHttpUtils`類，還用到了`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);//將java對象轉換為json字符串

response.getWriter().append("將發送請求給B");

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

System.out.println("來自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類

```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 發送POST方法的請求

*

* @param url

*? ? ? ? ? ? 發送請求的 URL

* @param param

*? ? ? ? ? ? 請求參數，請求參數應該是 name1=value1&name2=value2 的形式。

* @return 所代表遠程資源的響應結果

*/

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

PrintWriter out = null;

BufferedReader in = null;

String result = "";

try {

URL realUrl = new URL(url);

// 打開和URL之間的連接

URLConnection conn = realUrl.openConnection();

// 設置通用的請求屬性

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

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

conn.setRequestProperty("user-agent",

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

// 發送POST請求必須設置如下兩行

conn.setDoOutput(true);

conn.setDoInput(true);

// 獲取URLConnection對象對應的輸出流

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

// 發送請求參數

out.print(param);

// flush輸出流的緩沖

out.flush();

// 定義BufferedReader輸入流來讀取URL的響應

in = new BufferedReader(

new InputStreamReader(conn.getInputStream()));

String line;

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

result += line;

}

} catch (Exception e) {

System.out.println("發送 POST 請求出現異常！"+e);

e.printStackTrace();

}

//使用finally塊來關閉輸出流、輸入流

finally{

try{

if(out!=null){

out.close();

}

if(in!=null){

in.close();

}

}

catch(IOException ex){

ex.printStackTrace();

}

}

return result;

}

}

```

#### 2.BServlet部分

接收來自AServlet的數據String，然后通過fastjson包的parseObject方法把字符串轉成Stu對象，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為空");

return;

}

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

System.out.println();

System.out.println("收到請求，學生是: " + stu.getName());

response.getWriter().append("收到請求，學生是: " + stu.getName());

}

/**

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

*/

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

doPost(request, response);

}

}

```

總結

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