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后端Spring Boot+前端Android交互+MySQL增删查改（Java+Kotlin实现）

来源：SegmentFault 2023-01-09 20:40:01 0浏览收藏

本篇文章向大家介绍《后端Spring Boot+前端Android交互+MySQL增删查改（Java+Kotlin实现）》，主要包括MySQL、android、kotlin，具有一定的参考价值，需要的朋友可以参考一下。

1 前言&概述

这篇文章是基于这篇文章的更新，主要是更新了一些技术栈以及开发工具的版本，还有修复了一些Bug。

本文是

@Entity
@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    private String name;
    private String password;
}

基本的

@Repository
public interface UserRepository extends CrudRepository {
    boolean existsByName(String name);
    User findByNameAndPassword(String name,String password);
}

一个需要注意的点是

@Transactional
@Service
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
public class UserService {
    private final UserRepository repository;

    public boolean exists(User user){
        return repository.existsByName(user.getName());
    }

    public User findByNameAndPassword(User user){
        return repository.findByNameAndPassword(user.getName(),user.getPassword());
    }

    public boolean insert(User user){
        repository.save(user);
        return true;
    }

    public boolean update(User user){
        if(repository.findById(user.getId()).isEmpty()){
            return false;
        }
        repository.save(user);
        return true;
    }

    public boolean deleteById(int id){
        if(!repository.existsById(id)){
            return false;
        }
        repository.deleteById(id);
        return true;
    }
}

注解解释如下：

@RestController
@RequestMapping("/")
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
public class UserController {
    private final UserService service;

    @PostMapping("sign/in/up")
    public ResponseBody signInUp(@RequestBody User user) {
        if (service.exists(user)) {
            User u = service.findByNameAndPassword(user);
            return new ResponseBody(u != null ? ResponseCode.SIGN_IN_SUCCESS : ResponseCode.SIGN_IN_FAILED, u != null ? u.getId() : "");
        }
        return new ResponseBody(service.insert(user) ? ResponseCode.SIGN_UP_SUCCESS : ResponseCode.SIGN_UP_FAILED, "");
    }

    @PutMapping("update")
    public ResponseBody update(@RequestBody User user) {
        return new ResponseBody(service.update(user) ? ResponseCode.UPDATE_SUCCESS : ResponseCode.UPDATE_FAILED, "");
    }

    @DeleteMapping("delete")
    public ResponseBody deleteByName(@RequestParam int id) {
        return new ResponseBody(service.deleteById(id) ? ResponseCode.DELETE_SUCCESS : ResponseCode.DELETE_FAILED, "");
    }

    @GetMapping("test")
    public String test() {
        return "test";
    }
}

注解解释如下：

@Getter
@Setter
@AllArgsConstructor
@NoArgsConstructor
public class ResponseBody {
    private int code;
    private Object data;
}

响应码：

public class ResponseCode {
    public static final int SIGN_IN_SUCCESS = 2000;
    public static final int SIGN_UP_SUCCESS = 2001;
    public static final int UPDATE_SUCCESS = 2002;
    public static final int DELETE_SUCCESS = 2003;

    public static final int SIGN_IN_FAILED = 3000;
    public static final int SIGN_UP_FAILED = 3001;
    public static final int UPDATE_FAILED = 3002;
    public static final int DELETE_FAILED = 3003;
}

3.8 配置文件

spring:
  datasource:
    username: root
    password: 123456
    url: jdbc:mysql://localhost:3306/userinfo

  jpa:
    open-in-view: false
    hibernate:
      ddl-auto: update

数据库名字以及用户名密码请根据自己需要修改，

implementation 'com.squareup.okhttp3:okhttp:4.9.0'
implementation 'com.fasterxml.jackson.core:jackson-databind:2.12.1'
implementation 'org.bouncycastle:bcprov-jdk15to18:1.68'
implementation "org.projectlombok:lombok:1.18.16"
annotationProcessor 'org.projectlombok:lombok:1.18.16'

权限：


android:usesCleartextTraffic="true"

开启

buildFeatures{
    viewBinding = true
}

4.3 项目结构

4.4 实体类

@AllArgsConstructor
@NoArgsConstructor
@Getter
@Setter
public class User {
    private int id;
    private String name;
    private String password;

    public User(String name, String password) {
        this.name = name;
        this.password = password;
    }
}

4.5 工具类

public class Utils {
    private static final Keccak.Digest512 digest512 = new Keccak.Digest512();

    public static String encrypt(String origin) {
        return new String(Hex.encode(digest512.digest(origin.getBytes(StandardCharsets.UTF_8))));
    }

    public static String getResponseMessage(int code) {
        String message = "";
        switch (code) {
            case ResponseCode.SIGN_IN_SUCCESS:
                message = "登录成功";
                break;
            case ResponseCode.SIGN_UP_SUCCESS:
                message = "注册成功";
                break;
            case ResponseCode.SIGN_IN_FAILED:
                message = "用户名或密码错误";
                break;
            case ResponseCode.SIGN_UP_FAILED:
                message = "注册失败";
                break;
            case ResponseCode.DELETE_FAILED:
                message = "删除失败";
                break;
            case ResponseCode.DELETE_SUCCESS:
                message = "删除成功,自动退出";
                break;
            case ResponseCode.UPDATE_SUCCESS:
                message = "更新成功";
                break;
            case ResponseCode.UPDATE_FAILED:
                message = "更新失败";
                break;
            case ResponseCode.EMPTY_RESPONSE:
                message = "响应体为空";
                break;
            case ResponseCode.SERVER_ERROR:
                message = "服务器错误";
                break;
            case ResponseCode.JSON_SERIALIZATION:
                message = "JSON序列化错误";
                break;
            case ResponseCode.EXIT_SUCCESS:
                message = "退出成功";
                break;
            case ResponseCode.REQUEST_FAILED:
                message = "请求发送失败";
                break;
            case ResponseCode.UNCHANGED_INFORMATION:
                message = "未修改信息";
                break;
        }
        return message;
    }

    public static void showMessage(Context context, Message message) {
        Toast.makeText(context, getResponseMessage(message.what), Toast.LENGTH_SHORT).show();
    }
}

工具类有三个方法，分别是：

加密：将密码进行

@NoArgsConstructor
@Setter
@Getter
public class RestResponse {
    private int code;
    private Object data;
}

响应码：

public class ResponseCode {
    public static final int SIGN_IN_SUCCESS = 2000;
    public static final int SIGN_UP_SUCCESS = 2001;
    public static final int UPDATE_SUCCESS = 2002;
    public static final int DELETE_SUCCESS = 2003;

    public static final int SIGN_IN_FAILED = 3000;
    public static final int SIGN_UP_FAILED = 3001;
    public static final int UPDATE_FAILED = 3002;
    public static final int DELETE_FAILED = 3003;

    public static final int EMPTY_RESPONSE = 4000;
    public static final int SERVER_ERROR = 4001;
    public static final int REQUEST_FAILED = 4002;
    public static final int JSON_SERIALIZATION = 4003;
    public static final int EXIT_SUCCESS = 4004;
    public static final int UNCHANGED_INFORMATION = 4005;
}

4.7 请求

public class NetworkSettings {
    private static final String HOST = "192.168.1.8";
    private static final String PORT = "8080";
    public static final String SIGN_IN_UP = "http://"+ HOST +":"+PORT + "/sign/in/up";
    public static final String UPDATE = "http://"+ HOST +":"+PORT + "/update";
    public static final String DELETE = "http://"+ HOST +":"+PORT + "/delete";
}

4.8

public void signInUp(View view) {
    try {
        String name = binding.name.getText().toString();
        //SHA3-512加密
        String password = Utils.encrypt(binding.password.getText().toString());
        //构造OkHttp请求Request
        Request request = new Request.Builder().url(NetworkSettings.SIGN_IN_UP).post(
            //请求体类型为application/json;charset=utf-8，利用了Jackson序列化为JSON
            RequestBody.create(mapper.writeValueAsString(new User(name, password)), mediaType)
        ).build();
        //异步POST操作，传入一个Callback回调
        client.newCall(request).enqueue(new Callback() {
            //若失败
            @Override
            public void onFailure(@NotNull Call call, @NotNull IOException e) {
                //请求失败信息
                message.what = ResponseCode.REQUEST_FAILED;
                //展示对应信息，注意不能直接使用Toast.make(getApplicationContext(),"message",Toast.LENGTH_SHORT).show()
                //因为不是同一个线程，需要使用Handler提交，也就是post()方法，参数为一个线程
                handler.post(()->Utils.showMessage(getApplicationContext(),message));
                e.printStackTrace();
            }

            @Override
            public void onResponse(@NotNull Call call, @NotNull Response response) throws IOException {
                //如果成功
                if (response.isSuccessful()) {
                    //获取请求体
                    ResponseBody body = response.body();
                    //如果响应体不为空
                    if (body != null) {
                        //反序列化为响应体，包含了一个响应码以及数据字段
                        RestResponse restResponse = mapper.readValue(body.string(), RestResponse.class);
                        //设置Message
                        message.what = restResponse.getCode();
                        //如果登录成功
                        if(message.what == ResponseCode.SIGN_IN_SUCCESS){
                            handler.post(()->{
                                //存储用户id
                                signInId = (int)restResponse.getData();
                                //更新UI
                                binding.update.setVisibility(View.VISIBLE);
                                binding.delete.setVisibility(View.VISIBLE);
                                binding.signInUp.setText("退出");
                                binding.signInUp.setOnClickListener(v->signOut(false));
                                //保存旧用户名以及旧密码在更新的时候使用
                                oldName = binding.name.getText().toString();
                                oldPassword = binding.password.getText().toString();
                            });
                        }
                    } else {
                        //空响应体
                        message.what = ResponseCode.EMPTY_RESPONSE;
                        Log.e("RESPONSE_BODY_EMPTY", response.message());
                    }
                } else {
                    //服务器错误
                    message.what = ResponseCode.SERVER_ERROR;
                    Log.e("SERVER_ERROR", response.message());
                }
                //根据Message提示对应信息
                handler.post(()->Utils.showMessage(getApplicationContext(),message));
            }
        });
    } catch (JsonProcessingException e) {
        message.what = ResponseCode.JSON_SERIALIZATION;
        Utils.showMessage(getApplicationContext(),message);
        e.printStackTrace();
    }
}

这部分是登录注册的代码，还有更新用户信息以及删除用户的代码，大部分类似。