Android作为客户端，PC作为服务端：实现网络通信

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目录(?)[+]

此项目实现网络通信，android手机客户端去请求PC服务端，将PC上mysql中的数据显示在手机上。

PC服务端用JavaWeb写了个servlet，android手机客户端请求这个servlet，由servlet执行查询数据，并返回给手机客户端，服务器为Tomcat。

为了更清楚的展示，咱们现在mysql建一个测试表test

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create table test(

name varchar(20) primary key

);

插入几条记录，我们这里插入汉字，遇到乱码，我们可以去解决。

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insert into test values('张三');

insert into test values('李四');

insert into test values('王五');

插入成功



闲话少说，直接上代码：

PC服务端

我用MyEclipse建立了一个JavaWeb项目，这个项目中主要由一个数据查询类DBManager.java和一个servlet（loadMessage.java）组成

DBManager.java

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package com.njue.DBManager;

import java.awt.List;

import java.sql.*;

import java.util.ArrayList;

import org.omg.CORBA.Object;

public class DBManager {

;

String userName="root";

String password="123456";

Connection conn=null;

Statement stmt=null;

String url="jdbc:mysql://localhost:3306/mysql";

ArrayList<String> list=new ArrayList<String>();

String sql;

public DBManager(){

sql="select * from test;";

try {

Class.forName("com.mysql.jdbc.Driver");

conn=DriverManager.getConnection(url,userName,password);

stmt=conn.createStatement();

ResultSet rst=stmt.executeQuery(sql);

while(rst.next()){

//String name=new String(rst.getString("name").getBytes("latin1"), "UTF-8");

String name=new String(rst.getString("name").getBytes("latin1"), "GB2312");// 这句可要可不要，以你不出现乱码为准

//也可不用转化，直接写成String name=rst.getString("name");

list.add(name);

}

rst.close();

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

public ArrayList<String> getList(){

return list;

}

}

loadMessage.java

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package com.amaker.servlet;

import java.awt.List;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.ArrayList;

import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import com.njue.DBManager.DBManager;

public class loadMessage extends HttpServlet {

public loadMessage() {

super();

}

public void destroy() {

super.destroy(); // Just puts "destroy" string in log

// Put your code here

}

public void doGet(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

// request.setCharacterEncoding("UTF-8");

response.setContentType("text/html; charset=UTF-8" );

PrintWriter out = response.getWriter();

String message="";

DBManager db=new DBManager();

ArrayList<String> list=db.getList();

for(int i=0;i<list.size();i++){

message=message+list.get(i)+"\r\n";

}

out.print(message);

out.flush();

out.close();

}

public void doPost(HttpServletRequest request, HttpServletResponse response)

throws ServletException, IOException {

doGet(request,response);

}

public void init() throws ServletException {

// Put your code here

}

}

Android手机客户端代码：

AndroidClientActivity.java

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package com.njue.androidClient;

import android.app.Activity;

import android.os.Bundle;

import android.widget.TextView;

public class AndroidClientActivity extends Activity {

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

TextView tv=(TextView)findViewById(R.id.tv);

// 查询返回结果

String result = HttpUtil.queryStringForPost("http://10.0.2.2:8080/androidWeb/servlet/loadMessage");

//String result = HttpUtil.queryStringForPost("http://122.88.34.123:8080/androidWeb/servlet/loadMessage");

tv.setText(result);

}

}

HttpUtil.java

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package com.njue.androidClient;

import java.io.IOException;

import org.apache.http.HttpResponse;

import org.apache.http.client.ClientProtocolException;

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.util.EntityUtils;

public class HttpUtil {

// 基础URL

// 获得Get请求对象request

public static HttpGet getHttpGet(String url){

HttpGet request = new HttpGet(url);

return request;

}

// 获得Post请求对象request

public static HttpPost getHttpPost(String url){

HttpPost request = new HttpPost(url);

return request;

}

// 根据请求获得响应对象response

public static HttpResponse getHttpResponse(HttpGet request) throws ClientProtocolException, IOException{

HttpResponse response = new DefaultHttpClient().execute(request);

return response;

}

// 根据请求获得响应对象response

public static HttpResponse getHttpResponse(HttpPost request) throws ClientProtocolException, IOException{

HttpResponse response = new DefaultHttpClient().execute(request);

return response;

}

// 发送Post请求，获得响应查询结果

public static String queryStringForPost(String url){

// 根据url获得HttpPost对象

HttpPost request = HttpUtil.getHttpPost(url);

String result = null;

try {

// 获得响应对象

HttpResponse response = HttpUtil.getHttpResponse(request);

// 判断是否请求成功

if(response.getStatusLine().getStatusCode()==200){

// 获得响应

result = EntityUtils.toString(response.getEntity());

//result=new String(result.getBytes("8859_1"),"GB2312"); 这句可要可不要，以你不出现乱码为准

return result;

}

} catch (ClientProtocolException e) {

e.printStackTrace();

result = "网络异常！";

return result;

} catch (IOException e) {

e.printStackTrace();

result = "网络异常！";

return result;

}

return null;

}

}

当然还得在AndroidManifest.xml中加入网络访问权限：

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<uses-permission android:name="android.permission.INTERNET"></uses-permission>

需要注意的写服务器的主机号时，千万不能写localhost或者127.0.0.1，因为Android模拟器虽然和服务端程序在同一台电脑上，但两个毕竟是独立的系统，我们可以用10.0.2.2去访问本机。

运行结果：