网上有很多例子来演示Android客户端和服务器端数据如何实现交互不过这些例子大多比较繁杂，对于初学者来说这是不利的，现在介绍几种代码简单、逻辑清晰的交互例子，本篇博客介绍第二种：
一、服务器端：
代码1：添加名为“AndroidServerServlet.java”的文件
package com.ghj.packageofservlet;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 AndroidServerServlet extends HttpServlet { private static final long serialVersionUID = 6792396567928634227L; public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { response.setContentType("text/plain; charset=UTF-8"); request.setCharacterEncoding("UTF-8"); System.err.println(request.getParameter("clientData")); PrintWriter printWriter = response.getWriter(); printWriter.print("您好Android客户端！"); printWriter.flush(); printWriter.close(); }}代码2：修改名为“web.xml”的文件
<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <servlet-name>AndroidServerServlet</servlet-name> <servlet-class>com.ghj.packageofservlet.AndroidServerServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>AndroidServerServlet</servlet-name> <url-pattern>/AndroidServerServlet</url-pattern> </servlet-mapping></web-app>
二、Android手机客户端：
代码1：添加名为“AndroidClientActivity.java”的文件
package com.example.androidclient;import java.io.IOException;import java.io.UnsupportedEncodingException;import java.util.ArrayList;import java.util.List;import org.apache.http.HttpResponse;import org.apache.http.NameValuePair;import org.apache.http.client.ClientProtocolException;import org.apache.http.client.HttpClient;import org.apache.http.client.entity.UrlEncodedFormEntity;import org.apache.http.client.methods.HttpPost;import org.apache.http.impl.client.DefaultHttpClient;import org.apache.http.message.BasicNameValuePair;import org.apache.http.protocol.HTTP;import org.apache.http.util.EntityUtils;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class AndroidClientActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.android_client); Button sendButton = (Button) findViewById(R.id.send_button); sendButton.setOnClickListener(new OnClickListener(){ @Override public void onClick(View v) { new Thread(new Runnable(){ @Override public void run() { HttpPost httpRequest = new HttpPost("http://172.16.99.207:8080/AndroidServer/AndroidServerServlet"); List<NameValuePair> params = new ArrayList<NameValuePair>(); params.add(new BasicNameValuePair("clientData", "您好服务器端！")); try { Message message = new Message(); Bundle bundle = new Bundle(); httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));//设置请求参数项 HttpClient httpClient = new DefaultHttpClient(); HttpResponse httpResponse = httpClient.execute(httpRequest);//执行请求返回响应 if(httpResponse.getStatusLine().getStatusCode() == 200){//判断是否请求成功 bundle.putString("msg", EntityUtils.toString(httpResponse.getEntity())); }else{ bundle.putString("msg", "没有获取到Android服务器端的响应！"); } message.setData(bundle); handler.sendMessage(message); } catch (ClientProtocolException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }).start(); } }); } private Handler handler = new Handler(){ @Override public void handleMessage(Message message) { super.handleMessage(message); Bundle bundle = message.getData(); String msg = bundle.getString("msg"); Toast.makeText(getApplicationContext(), msg, Toast.LENGTH_LONG).show(); } };} 代码2：添加名为“android_client.xml”的文件
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context=".MainActivity" > <Button android:id="@+id/send_button" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_centerHorizontal="true" android:layout_centerVertical="true" android:text="@string/hello_server" /></RelativeLayout>
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