Android HTTP实例使用GET方法和POST方法发送请求

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

　　第二个页面显示结果：

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：

<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_http_demo2.xml

主要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。

　　关于这点的讨论也可以查看本博客其他文章：

　　http://www.cnblogs.com/mengdd/archive/2013/05/26/3099776.html

　　http://www.cnblogs.com/mengdd/archive/2013/06/12/3132702.html

　　程序运行结果如下：

参考资料

　　Android开发视频教程HTTP操作。——http://www.marsdroid.org

　　Android Reference: package org.apache.http:

　　http://developer.android.com/reference/org/apache/http/package-summary.html

　　之前文章中，关于GET和POST的更多讨论：

　　http://www.cnblogs.com/mengdd/archive/2013/05/26/3099776.html

　　http://www.cnblogs.com/mengdd/archive/2013/06/12/3132702.html