網上有很多例子來演示Android客戶端和伺服器端資料如何實現互動不過這些例子大多比較繁雜，對於初學者來說這是不利的，現在介紹幾種程式碼簡單、邏輯清晰的互動例子，本篇部落格介紹第四種：

        一、伺服器端：

        程式碼1：新增名為“AndroidServerServlet.java”的檔案

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客戶端！");
		printWriter.flush();
		printWriter.close();
	}
}
 

        程式碼2：修改名為“web.xml”的檔案

<?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手機客戶端：

        程式碼2：新增名為“AndroidClientActivity.java”的檔案

package com.example.androidclient;

import org.apache.http.Header;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;

import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;
import com.loopj.android.http.RequestParams;

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) {
				RequestParams requestParams = new RequestParams();
				requestParams.add("clientData", "您好伺服器端！");
				new AsyncHttpClient().post("http://172.16.99.207:8080/AndroidServer/AndroidServerServlet", requestParams, new AsyncHttpResponseHandler() {
					@Override
					public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
						if(statusCode == 200){
							Toast.makeText(AndroidClientActivity.this, new String(responseBody), Toast.LENGTH_LONG).show();
						}
					}
					@Override
					public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {
						Toast.makeText(AndroidClientActivity.this, "沒有獲取到Android伺服器端的響應！", Toast.LENGTH_LONG).show();
					}
				});
			}
		});
	}
}
 

        程式碼3：新增名為“android_client.xml”的檔案

<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>

        說明：使用android-async-http-1.4.6.jar jar這種形式實現Android客戶端和伺服器端資料互動是最常用的。