Web程序：使用GET和POST方法发送请求
首先利用MyEclispe+Tomcat写好一个Web程序，实现的功能就是提交用户信息：用户名和年龄，使用GET和POST两种提交方式。
用浏览器打开：
不管以哪一种方式，提交以后显示如下页面，将提交的信息再显示出来。
关键代码如下：
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP ‘index.jsp‘ starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
This is 圣骑士Wind‘s page. <br>
<p>
以GET方法发送：<br>
<form action="servlet/WelcomeUserServlet" method="get">
Username: <input type="text" name="username" value="">
Age: <input type="text" name="age" value="">
<input type="submit" value="Submit">
</form>
</p>
<p>
以POST方法发送：<br>
<form action="servlet/WelcomeUserServlet" method="post">
Username: <input type="text" name="username" value="">
Age: <input type="text" name="age" value="">
<input type="submit" value="Submit">
</form>
</p>
</body>
</html>
index.jsp显示结果：
package com.shengqishiwind;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class WelcomeUserServlet extends HttpServlet
{
/**
* The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
process(request, response);
}
/**
* The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
process(request, response);
}
private void process(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException
{
String username = request.getParameter("username");
String age = request.getParameter("age");
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><head><title>Welcome!</title></head>");
out.println("<body> Welcome my dear friend!<br>");
out.println("Your name is: " + username + "<br>");
out.println("And your age is: " + age + "</body></html>");
out.flush();
out.close();
}
}
WelcomeUserServlet
Android程序：使用GET方法和POST方法发送请求
上面是用浏览器访问页面并提交数据，如果想在Android客户端提交，服务器端的代码是不用变的，只要写好客户端代码即可：
首先要在manifest中加上访问网络的权限：
<manifest ... >
<uses-permission android:name="android.permission.INTERNET" />
...
</manifest>
布局文件activity_http_demo2.xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Username:" />
<EditText
android:id="@+id/name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="text" />
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="User Age:" />
<EditText
android:id="@+id/age"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:inputType="number" />
<Button
android:id="@+id/submit_get"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Submit using GET" />
<Button
android:id="@+id/submit_post"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Submit using POST" />
<TextView
android:id="@+id/result"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="#0000FF"
android:textSize="14sp">
</TextView>
</LinearLayout>
Activity代码如下：
package com.example.httpdemo2;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class HttpDemo2Activity extends Activity
{
private String TAG = "http";
private EditText mNameText = null;
private EditText mAgeText = null;
private Button getButton = null;
private Button postButton = null;
private TextView mResult = null;
// 基本地址：服务器ip地址：端口号/Web项目逻辑地址+目标页面（Servlet）的url-pattern
private String baseURL = "http://192.168.11.6:8080/HelloWeb/servlet/WelcomeUserServlet";
@Override
protected void onCreate(Bundle savedInstanceState)
{
Log.i(TAG, "onCreate");
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_http_demo2);
mNameText = (EditText) findViewById(R.id.name);
mAgeText = (EditText) findViewById(R.id.age);
mResult = (TextView) findViewById(R.id.result);
getButton = (Button) findViewById(R.id.submit_get);
getButton.setOnClickListener(mGetClickListener);
postButton = (Button) findViewById(R.id.submit_post);
postButton.setOnClickListener(mPostClickListener);
}
private OnClickListener mGetClickListener = new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Log.i(TAG, "GET request");
// 先获取用户名和年龄
String name = mNameText.getText().toString();
String age = mAgeText.getText().toString();
// 使用GET方法发送请求,需要把参数加在URL后面，用？连接，参数之间用&分隔
String url = baseURL + "?username=" + name + "&age=" + age;
// 生成请求对象
HttpGet httpGet = new HttpGet(url);
HttpClient httpClient = new DefaultHttpClient();
// 发送请求
try
{
HttpResponse response = httpClient.execute(httpGet);
// 显示响应
showResponseResult(response);// 一个私有方法，将响应结果显示出来
}
catch (Exception e)
{
e.printStackTrace();
}
}
};
private OnClickListener mPostClickListener = new View.OnClickListener()
{
@Override
public void onClick(View v)
{
Log.i(TAG, "POST request");
// 先获取用户名和年龄
String name = mNameText.getText().toString();
String age = mAgeText.getText().toString();
NameValuePair pair1 = new BasicNameValuePair("username", name);
NameValuePair pair2 = new BasicNameValuePair("age", age);
List<NameValuePair> pairList = new ArrayList<NameValuePair>();
pairList.add(pair1);
pairList.add(pair2);
try
{
HttpEntity requestHttpEntity = new UrlEncodedFormEntity(
pairList);
// URL使用基本URL即可，其中不需要加参数
HttpPost httpPost = new HttpPost(baseURL);
// 将请求体内容加入请求中
httpPost.setEntity(requestHttpEntity);
// 需要客户端对象来发送请求
HttpClient httpClient = new DefaultHttpClient();
// 发送请求
HttpResponse response = httpClient.execute(httpPost);
// 显示响应
showResponseResult(response);
}
catch (Exception e)
{
e.printStackTrace();
}
}
};
/**
* 显示响应结果到命令行和TextView
* @param response
*/
private void showResponseResult(HttpResponse response)
{
if (null == response)
{
return;
}
HttpEntity httpEntity = response.getEntity();
try
{
InputStream inputStream = httpEntity.getContent();
BufferedReader reader = new BufferedReader(new InputStreamReader(
inputStream));
String result = "";
String line = "";
while (null != (line = reader.readLine()))
{
result += line;
}
System.out.println(result);
mResult.setText("Response Content from server: " + result);
}
catch (Exception e)
{
e.printStackTrace();
}
}
}
可以从中对比GET方法和POST方法的区别：
GET方法需要用？将参数连接在URL后面，各个参数之间用&连接。
POST方法发送请求时，仍然使用基本的URL，将参数信息放在请求实体中发送。
程序运行结果如下：
时间： 2024-08-02 16:45:25