Android客户端和服务器端数据交互

 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，本篇博客介绍第四种：

        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：下载名为android-async-http-1.4.6.jar的jar文件，下载地址：http://download.csdn.net/download/wangshuxuncom/8116169

        代码2：添加名为“AndroidClientActivity.java”的文件

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", "您好服务器端！");
                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, "没有获取到Android服务器端的响应！", Toast.LENGTH_LONG).show();
                    }
                });
            }
        });
    }
}

        代码3：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>

        说明：使用android-async-http-1.4.6.jar jar这种形式实现Android客户端和服务器端数据交互是最常用的。