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
1 public class MainActivity extends AppCompatActivity implements View.OnClickListener {
2
3 private EditText stu_number, stu_name;
4 private Button btn_search;
5 private OkHttpClient okhttpClient;
6 private String stu_number_txt;
7
8
9 @Override
10 protected void onCreate(Bundle savedInstanceState) {
11 super.onCreate(savedInstanceState);
12 setContentView(R.layout.activity_main);
13 initView();
14 }
15
16 public void initView() {
17 btn_search = (Button) findViewById(R.id.btn_search);
18 stu_number = (EditText) findViewById(R.id.stu_number);
19 stu_name = (EditText) findViewById(R.id.stu_name);
20 btn_search.setOnClickListener(this);
21 }
22
23 @Override
24 public void onClick(View view) {
25 if (view.getId() == R.id.btn_search) {
26 //获取输入的学号
27 stu_number_txt = stu_number.getText().toString();
28 new Thread(new Runnable() {
29 @Override
30 public void run() {
31 sendRequest(stu_number_txt);
32 }
33 }).start();
34
35 }
36 }
37
38 private void sendRequest(String stu_number_txt) {
39 Map map = new HashMap();
40 map.put("stu_number", stu_number_txt);
41 JSONObject jsonObject = new JSONObject(map);
42 String jsonString = jsonObject.toString();
43 // Log.d("这将JSON对象转换为json字符串", jsonString);
44 RequestBody body = RequestBody.create(null, jsonString);//以字符串方式
45 okhttpClient = new OkHttpClient();
46 final Request request = new Request.Builder()
47 .url("http://192.168.43.218:8080/AndroidServerDemo/SearchServlet")
48 .post(body)
49 .build();
50 Call call = okhttpClient.newCall(request);
51 call.enqueue(new Callback() {
52 @Override
53 public void onFailure(Call call, IOException e) {
54 runOnUiThread(new Runnable() {
55 @Override
56 public void run() {
57 Toast.makeText(MainActivity.this, "连接失败！", Toast.LENGTH_SHORT).show();
58 }
59 });
60 e.printStackTrace();
61 }
62
63 @Override
64 public void onResponse(Call call, Response response) throws IOException {
65 // runOnUiThread(new Runnable() {
66 // @Override
67 // public void run() {
68 // Toast.makeText(MainActivity.this,"连接成功！",Toast.LENGTH_SHORT).show();
69 // }
70 // });
71 String res = response.body().string();//获取到传过来的字符串
72 try {
73 JSONObject jsonObj = new JSONObject(res);
74 String stu_name = jsonObj.getString("stu_name");
75 showRequestResult(stu_name);
76 } catch (JSONException e) {
77 e.printStackTrace();
78 }
79 }
80 });
81 }
82
83 private void showRequestResult(final String response) {
84 runOnUiThread(new Runnable() {
85 @Override
86 /**
87 * 实时更新，数据库信息改变时，客户端内容发生改变
88 */
89 public void run() {
90 stu_name.setText(response);
91 }
92 });
93 }
94 }
服务器端：
ConnDb.java：
1 package com.thanlon.dao;
2
3 import java.sql.*;
4
5 public class ConnDb {
6 private String driverName = "com.mysql.jdbc.Driver";
7 private String username = "root";
8 private String password = "123456";
9 private String url = "jdbc:mysql://localhost:3306/androidDb";
10
11 public Connection conn() {
12 try {
13 Class.forName(driverName);
14 try {
15 Connection conn = DriverManager.getConnection(url,username,password);
16 return conn;
17 } catch (SQLException e) {
18 // TODO Auto-generated catch block
19 e.printStackTrace();
20 System.out.println("连接数据库失败！");
21 }
22 } catch (ClassNotFoundException e) {
23 // TODO Auto-generated catch block
24 e.printStackTrace();
25 System.out.println("加载驱动失败！");
26 }
27 return null;
28 }
29 }
TextConn.java：
1 package Test;
2
3 import org.junit.Test;
4
5 import com.thanlon.dao.ConnDb;
6
7 public class TestConn {
8 /**
9 * 测试能否正常连接数据库
10 */
11 @Test
12 public void TestConnDb() {
13 ConnDb connDb = new ConnDb();
14 System.out.println(connDb.conn());
15 }
16 }
SearchServlet.java：
1 package com.thanlon.servlet;
2
3 import java.io.BufferedReader;
4 import java.io.IOException;
5 import java.io.PrintWriter;
6
7 import javax.servlet.ServletException;
8 import javax.servlet.http.HttpServlet;
9 import javax.servlet.http.HttpServletRequest;
10 import javax.servlet.http.HttpServletResponse;
11
12 import com.thanlon.services.SearchNameServices;
13
14 import net.sf.json.JSONObject;
15
16 public class SearchServlet extends HttpServlet {
17 @Override
18 protected void doPost(HttpServletRequest request,
19 HttpServletResponse response) throws ServletException, IOException {
20 // TODO Auto-generated method stub
21 response.setContentType("text/html;charset=utf-8");
22 // System.out.println("连接成功反馈");// 测试是否成功连接
23 StringBuffer json1 = new StringBuffer();// 字符流
24 String line = null;
25 BufferedReader reader = request.getReader();// 读取流
26 while ((line = reader.readLine()) != null) {
27 json1.append(line);// 接受的是JSON格式
28 }
29
30 System.out.println(json1);//得到的是JSON格式
31 // System.out.println(json1.toString());//得到的是字符串，虽然控制台输出一样
32 // 把得到的字符串封装为JSON，再获取里面的传过来用户名
33 JSONObject jsonObject = JSONObject.fromObject(json1.toString());
34 String stu_number = jsonObject.getString("stu_number");
35 System.out.println(stu_number);
36
37 // 连接本地数据库(采用MySql数据库 )
38 String stuName = SearchNameServices.selectNameInfo(stu_number);
39 System.out.println(stuName);
40
41 PrintWriter out = response.getWriter();
42 // 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
43
44 String stu_name_json = "{"stu_name":""+stuName+""}";//组装json格式的字符串来传送
45 System.out.println(stu_name_json);
46 out.write(stu_name_json);
47 out.flush();
48 out.close();
49 }
50
51 @Override
52 protected void doGet(HttpServletRequest request,
53 HttpServletResponse response) throws ServletException, IOException {
54 // TODO Auto-generated method stub
55 // super.doGet(req, resp);
56
57 response.setContentType("text/html;charset=utf-8");
58 PrintWriter out = response.getWriter();
59 out.flush();
60 out.close();
61 }
62 }
SearchNameServices.java：
1 package com.thanlon.services;
2
3 import java.sql.PreparedStatement;
4 import java.sql.ResultSet;
5 import java.sql.SQLException;
6
7 import javax.naming.spi.DirStateFactory.Result;
8 import javax.validation.constraints.Null;
9
10 import com.thanlon.dao.ConnDb;
11
12 public class SearchNameServices {
13
14 public static String selectNameInfo(String stu_number){
15 String stu_nameString = null;
16 String sql = "select *from student where stu_number = '"+stu_number+"'";
17 ConnDb connDb = new ConnDb();
18 try {
19 // 执行SQL语句
20 PreparedStatement ps = connDb.conn().prepareStatement(sql);
21 ResultSet rs = ps.executeQuery();
22 if (rs.next()) {
23 stu_nameString =rs.getString("stu_name");
24 return stu_nameString;
25 }else {
26 return stu_nameString="查无此人";
27 }
28 } catch (SQLException e) {
29 // TODO Auto-generated catch block
30 e.printStackTrace();
31 System.out.println("执行SQL语句出错！");
32 }
33 return null;
34 }
35 }
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