Android+Servlet+MySql+JSON实现简单的数据查询操作--C/S架构

本例简单地实现Android客户端与服务器端交互，主要是通过客户端输入内容(学号)提交到服务器端，服务器端与数据库交互去查询相应信息(姓名)。根据这个做个完整的安卓登录是没问题的。本例数据库服务器都采用本地，测试时Android客户端与服务端在同一网络中！

1、本例演示截图：

当输入错误的学号(与数据库不匹配)，显示查无此人

当输入正确的学号时，显示学号对应的学生姓名：

2、数据模型：

3、客户端：

本例客户端发送请求给服务器端，附带JSON格式字符串（学号{"stu_number":"123456789"}）,当然这是最简单的JSON格式。

4、服务器端：(项目目录）

ConnDb.java:返回连接对象，通过测试类TextConn.java可测试与数据库连接是否正常。

SearchNameServices.java：业务类、核心类，处理与数据库交互的逻辑问题，返回从数据库获取的结果

SearchServlet.java：servlet类，将客户端请求的数据返回给客户端，可以对数据做处理，回传给客户端(这里将获取的用户名进行封装，转换成JSON格式字符串来传送)

5、核心代码

Android客户端：

MainActivity.java：

Package

 public class MainActivity extends AppCompatActivity implements View.OnClickListener {

     private EditText stu_number, stu_name;
     private Button btn_search;
     private OkHttpClient okhttpClient;
     private String stu_number_txt;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         initView();
     }

     public void initView() {
         btn_search = (Button) findViewById(R.id.btn_search);
         stu_number = (EditText) findViewById(R.id.stu_number);
         stu_name = (EditText) findViewById(R.id.stu_name);
         btn_search.setOnClickListener(this);
     }

     @Override
     public void onClick(View view) {
         if (view.getId() == R.id.btn_search) {
             //获取输入的学号
             stu_number_txt = stu_number.getText().toString();
             new Thread(new Runnable() {
                 @Override
                 public void run() {
                     sendRequest(stu_number_txt);
                 }
             }).start();

         }
     }

     private void sendRequest(String stu_number_txt) {
         Map map = new HashMap();
         map.put("stu_number", stu_number_txt);
         JSONObject jsonObject = new JSONObject(map);
         String jsonString = jsonObject.toString();
 //        Log.d("这将JSON对象转换为json字符串", jsonString);
         RequestBody body = RequestBody.create(null, jsonString);//以字符串方式
         okhttpClient = new OkHttpClient();
         final Request request = new Request.Builder()
                 .url("http://192.168.43.218:8080/AndroidServerDemo/SearchServlet")
                 .post(body)
                 .build();
         Call call = okhttpClient.newCall(request);
         call.enqueue(new Callback() {
             @Override
             public void onFailure(Call call, IOException e) {
                 runOnUiThread(new Runnable() {
                     @Override
                     public void run() {
                         Toast.makeText(MainActivity.this, "连接失败！", Toast.LENGTH_SHORT).show();
                     }
                 });
                 e.printStackTrace();
             }

             @Override
             public void onResponse(Call call, Response response) throws IOException {
 //                runOnUiThread(new Runnable() {
 //                    @Override
 //                    public void run() {
 //                        Toast.makeText(MainActivity.this,"连接成功！",Toast.LENGTH_SHORT).show();
 //                    }
 //                });
                 String res = response.body().string();//获取到传过来的字符串
                 try {
                     JSONObject jsonObj = new JSONObject(res);
                     String stu_name = jsonObj.getString("stu_name");
                     showRequestResult(stu_name);
                 } catch (JSONException e) {
                     e.printStackTrace();
                 }
             }
         });
     }

     private void showRequestResult(final String response) {
         runOnUiThread(new Runnable() {
             @Override
             /**
              * 实时更新，数据库信息改变时，客户端内容发生改变
              */
             public void run() {
                 stu_name.setText(response);
             }
         });
     }
 }

服务器端：

ConnDb.java：

 package com.thanlon.dao;

 import java.sql.*;

 public class ConnDb {
     private String driverName = "com.mysql.jdbc.Driver";
     private String username = "root";
     private String password = "123456";
     private String url = "jdbc:mysql://localhost:3306/androidDb";

     public Connection conn() {
         try {
             Class.forName(driverName);
             try {
                 Connection conn = DriverManager.getConnection(url,username,password);
                 return conn;
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
                 System.out.println("连接数据库失败！");
             }
         } catch (ClassNotFoundException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
             System.out.println("加载驱动失败！");
         }
         return null;
     }
 }

TextConn.java：

 package Test;

 import org.junit.Test;

 import com.thanlon.dao.ConnDb;

 public class TestConn {
     /**
      * 测试能否正常连接数据库
      */
     @Test
     public void TestConnDb() {
         ConnDb connDb = new ConnDb();
         System.out.println(connDb.conn());
     }
 }

SearchServlet.java：

 package com.thanlon.servlet;

 import java.io.BufferedReader;
 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;

 import com.thanlon.services.SearchNameServices;

 import net.sf.json.JSONObject;

 public class SearchServlet extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest request,
             HttpServletResponse response) throws ServletException, IOException {
         // TODO Auto-generated method stub
         response.setContentType("text/html;charset=utf-8");
 //        System.out.println("连接成功反馈");// 测试是否成功连接
         StringBuffer json1 = new StringBuffer();// 字符流
         String line = null;
         BufferedReader reader = request.getReader();// 读取流
         while ((line = reader.readLine()) != null) {
             json1.append(line);// 接受的是JSON格式
         }

         System.out.println(json1);//得到的是JSON格式
         // System.out.println(json1.toString());//得到的是字符串，虽然控制台输出一样
         // 把得到的字符串封装为JSON，再获取里面的传过来用户名
         JSONObject jsonObject = JSONObject.fromObject(json1.toString());
         String stu_number = jsonObject.getString("stu_number");
         System.out.println(stu_number);

 //        连接本地数据库(采用MySql数据库 )
         String stuName = SearchNameServices.selectNameInfo(stu_number);
         System.out.println(stuName);

         PrintWriter out = response.getWriter();
 //        out.write(stuName);//本直接返回查到的姓名，在Android客户端显示就行，这里还是封装成JSON格式发送吧

         String  stu_name_json  = "{\"stu_name\":\""+stuName+"\"}";//组装json格式的字符串来传送
         System.out.println(stu_name_json);
         out.write(stu_name_json);
         out.flush();
         out.close();
     }

     @Override
     protected void doGet(HttpServletRequest request,
             HttpServletResponse response) throws ServletException, IOException {
         // TODO Auto-generated method stub
         // super.doGet(req, resp);

         response.setContentType("text/html;charset=utf-8");
         PrintWriter out = response.getWriter();
         out.flush();
         out.close();
     }
 }

SearchNameServices.java：

 package com.thanlon.services;

 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;

 import javax.naming.spi.DirStateFactory.Result;
 import javax.validation.constraints.Null;

 import com.thanlon.dao.ConnDb;

 public class SearchNameServices {

     public static String selectNameInfo(String stu_number){
         String stu_nameString = null;
         String sql = "select *from student  where  stu_number = '"+stu_number+"'";
         ConnDb connDb = new ConnDb();
         try {
 //            执行SQL语句
             PreparedStatement ps =  connDb.conn().prepareStatement(sql);
             ResultSet rs =  ps.executeQuery();
             if (rs.next()) {
                 stu_nameString =rs.getString("stu_name");
                 return stu_nameString;
             }else {
                 return stu_nameString="查无此人";
             }
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
             System.out.println("执行SQL语句出错！");
         }
         return null;
     }
 }

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