android登陆界面访问数据库

String sql = "SELECT * FROM users WHERE username = ? AND password = ?";
PreparedStatement pstmt = connection.prepareStatement(sql);
pstmt.setString(1, username);
pstmt.setString(2, password);
ResultSet rs = pstmt.executeQuery();

// 使用 Retrofit 进行网络请求
public interface ApiService {
    @POST("login")
    Call<LoginResponse> login(@Body LoginRequest request);
}

// 登录请求
public class LoginRequest {
    private String username;
    private String password;

    // getters and setters
}

// 登录响应
public class LoginResponse {
    private boolean success;
    private String message;

    // getters and setters
}

// 发起登录请求
ApiService apiService = RetrofitClient.getClient().create(ApiService.class);
LoginRequest request = new LoginRequest();
request.setUsername("user");
request.setPassword("pass");
Call<LoginResponse> call = apiService.login(request);
call.enqueue(new Callback<LoginResponse>() {
    @Override
    public void onResponse(Call<LoginResponse> call, Response<LoginResponse> response) {
        if (response.isSuccessful()) {
            LoginResponse loginResponse = response.body();
            if (loginResponse.isSuccess()) {
                // 登录成功
            } else {
                // 登录失败
            }
        }
    }

    @Override
    public void onFailure(Call<LoginResponse> call, Throwable t) {
        // 请求失败
    }
});

@RestController
public class LoginController {

    @Autowired
    private UserRepository userRepository;

    @PostMapping("/login")
    public ResponseEntity<LoginResponse> login(@RequestBody LoginRequest request) {
        String username = request.getUsername();
        String password = request.getPassword();

        User user = userRepository.findByUsername(username);
        if (user != null && user.getPassword().equals(password)) {
            LoginResponse response = new LoginResponse();
            response.setSuccess(true);
            response.setMessage("登录成功");
            return ResponseEntity.ok(response);
        } else {
            LoginResponse response = new LoginResponse();
            response.setSuccess(false);
            response.setMessage("用户名或密码错误");
            return ResponseEntity.status(HttpStatus.UNAUTHORIZED).body(response);
        }
    }
}