在某些情况下，需要用Java applicatioin来模拟form，向服务器(本文以servlet为例)发送http post请求，包括提交表单域中的数据以及上传文件。如果仅仅是传递form中的数据，而不包含上传文件，那是很简单的，比如Java application可以这么写：
package com.pat.postrequestemulator;
importjava.io.BufferedReader;
importjava.io.InputStream;
importjava.io.InputStreamReader;
importjava.io.OutputStreamWriter;
importjava.net.HttpURLConnection;
importjava.net.URL;
public classPostRequestEmulator
{
public static void main(String[] args)throws Exception
{
// 服务地址
URL url = newURL("http://127.0.0.1:8080/test/upload");
// 设定连接的相关参数
HttpURLConnection connection= (HttpURLConnection) url.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
OutputStreamWriter out = newOutputStreamWriter(connection.getOutputStream(), "UTF-8");
// 向服务端发送key = value对
out.write("username=kevin&password=pass");
out.flush();
out.close();
// 获取服务端的反馈
String strLine="";
String strResponse ="";
InputStream in =connection.getInputStream();
BufferedReader reader = newBufferedReader(new InputStreamReader(in));
while((strLine =reader.readLine()) != null)
{
strResponse +=strLine +"\n";
}
System.out.print(strResponse);
}
}
服务端的servlet可以这么写：
packagecom.pat.handlinghttprequestservlet;
importjava.io.IOException;
importjava.io.PrintWriter;
importjavax.servlet.ServletException;
importjavax.servlet.http.HttpServlet;
importjavax.servlet.http.HttpServletRequest;
importjavax.servlet.http.HttpServletResponse;
public classHandlingHttpRequestServlet extends HttpServlet
{
private static final longserialVersionUID = 1L;
@Override
protected void doGet(HttpServletRequestreq, HttpServletResponse resp)
throws ServletException, IOException
{
super.doGet(req, resp);
}
@Override
protected voiddoPost(HttpServletRequest req, HttpServletResponse resp)
throwsServletException, IOException
{
String username =req.getParameter("username"); //获取username所对应的value
String password =req.getParameter("password"); //获取password所对应的value
System.out.println("Thereceived username and password is: " + username + "/" +password);
// 向请求端发回反馈信息
PrintWriter out =resp.getWriter();
out.print("OK");
out.flush();
out.close();
super.doPost(req, resp);
}
}
一切看起来都不复杂。但是如果要模拟的表单，除了要向服务器传递如上面的“key = value”这样的普通信息，同时还要上传文件，事情就复杂得多。