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，本篇博客介绍第三种：
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="/xml/ns/javaee"xmlns:xsi="/2001/XMLSchema-instance"xsi:schemaLocation="/xml/ns/javaee /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.Looper;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.Toast;public class AndroidClientActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.android_client);Button sendButton = (Button) findViewById(R.id.send_button);sendButton.setOnClickListener(new OnClickListener(){@Overridepublic void onClick(View v) {new Thread(new Runnable(){@Overridepublic void run() {Looper.prepare();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 {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Toast.makeText(AndroidClientActivity.this, EntityUtils.toString(httpResponse.getEntity()), Toast.LENGTH_LONG).show();}else{Toast.makeText(AndroidClientActivity.this, "没有获取到Android服务器端的响应！", Toast.LENGTH_LONG).show();}} catch (ClientProtocolException e) {e.printStackTrace();} catch (UnsupportedEncodingException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}Looper.loop();}}).start();}});}}
注意：上面代码第41行和第61行不可缺少，否则会出现java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()异常，关于该异常请参见另一篇名为《Android中的Can't create handler inside thread that has not called Looper.prepare()异常》博客。
代码2：添加名为“android_client.xml”的文件
<RelativeLayout xmlns:android="/apk/res/android"xmlns:tools="/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" ><Buttonandroid: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>
【0分下载该Demo】
