Android HTTP实例使用GET方法和POST方法发送请求

作者: siediyer 分类: Android 发布时间: 2017-10-16 11:37

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：