Android作为客户端，PC作为服务端：实现网络通信

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

 

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。

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

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 blocke.printStackTrace();}}public ArrayList<String> getList(){return list;}}

 

loadMessage.java

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

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

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requestpublic static HttpGet getHttpGet(String url){HttpGet request = new HttpGet(url); return request;}// 获得Post请求对象requestpublic static HttpPost getHttpPost(String url){ HttpPost request = new HttpPost(url); return request;}// 根据请求获得响应对象responsepublic 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responsepublic 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：

<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：

 

这是在模拟器上运行，有的同学有这样的想法，把ip改成自己电脑真实的Ip，把客户端拿到真机上去实验，但运行后会发现会显示“网络异常”，不能访问。这里涉及到了网络方面的问题，其实也非常简单。下篇博客将会详细的讲解，去解决这个问题。

 

 

 补充：上传两个项目，不禁可以访问mysql，也可以访问Access数据库。

下载地址：http://download.csdn.net/detail/pzhtpf/4388157