告别混乱代码：SpringBoot 后端接口规范

<dependency>
<!--新版框架没有自动引入需要手动引入-->
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-validation</artifactId>
</dependency>
<dependency>
    <groupId>com.github.xiaoymin</groupId>
    <artifactId>knife4j-spring-boot-starter</artifactId>
    <!--在引用时请在maven中央仓库搜索最新版本号-->
    <version>2.0.2</version>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <optional>true</optional>
</dependency>

@PostMapping("/addUser")
public String addUser(@RequestBody @Validated User user, BindingResult bindingResult) {
    // 如果有参数校验失败，会将错误信息封装成对象组装在BindingResult里
    List<ObjectError> allErrors = bindingResult.getAllErrors();
    if(!allErrors.isEmpty()){
        return allErrors.stream()
            .map(o->o.getDefaultMessage())
            .collect(Collectors.toList()).toString();
    }
    // 返回默认的错误信息
    // return allErrors.get(0).getDefaultMessage();
    return validationService.addUser(user);
}

@Data
public class User {
    @NotNull(message = "用户id不能为空")
    private Long id;
    @NotNull(message = "用户账号不能为空")
    @Size(min = 6, max = 11, message = "账号长度必须是6-11个字符")
    private String account;
    @NotNull(message = "用户密码不能为空")
    @Size(min = 6, max = 11, message = "密码长度必须是6-11个字符")
    private String password;
    @NotNull(message = "用户邮箱不能为空")
    @Email(message = "邮箱格式不正确")
    private String email;
}

@Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
@Retention(RUNTIME)
@Documented
@Constraint(validatedBy = {HaveNoBlankValidator.class})// 标明由哪个类执行校验逻辑
public @interface HaveNoBlank {
    // 校验出错时默认返回的消息
    String message() default "字符串中不能含有空格";
    Class<?>[] groups() default { };
    Class<? extends Payload>[] payload() default { };
    /**
     * 同一个元素上指定多个该注解时使用
     */
    @Target({ METHOD, FIELD, ANNOTATION_TYPE, CONSTRUCTOR, PARAMETER, TYPE_USE })
    @Retention(RUNTIME)
    @Documented
    public @interface List {
        NotBlank[] value();
    }
}

public class HaveNoBlankValidator implements ConstraintValidator<HaveNoBlank, String> {
    @Override
    public boolean isValid(String value, ConstraintValidatorContext context) {
        // null 不做检验
        if (value == null) {
            return true;
        }
        // 校验失败
        return !value.contains(" ");
        // 校验成功
    }
}

package com.csdn.demo1.global;
import org.springframework.validation.ObjectError;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestControllerAdvice;
@RestControllerAdvice
@ResponseBody
public class ExceptionControllerAdvice {
    @ExceptionHandler(MethodArgumentNotValidException.class)
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    public String MethodArgumentNotValidExceptionHandler(MethodArgumentNotValidException e) {
        // 从异常对象中拿到ObjectError对象
        ObjectError objectError = e.getBindingResult().getAllErrors().get(0);
        // 然后提取错误提示信息进行返回
        return objectError.getDefaultMessage();
    }
     /**
     * 系统异常 预期以外异常
     */
    @ExceptionHandler(Exception.class)
    @ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR)
    public ResultVO<?> handleUnexpectedServer(Exception ex) {
        log.error("系统异常：", ex);
        // GlobalMsgEnum.ERROR是我自己定义的枚举类
        return new ResultVO<>(GlobalMsgEnum.ERROR);
    }
    /**
     * 所以异常的拦截
     */
    @ExceptionHandler(Throwable.class)
    @ResponseStatus(value = HttpStatus.INTERNAL_SERVER_ERROR)
    public ResultVO<?> exception(Throwable ex) {
        log.error("系统异常：", ex);
        return new ResultVO<>(GlobalMsgEnum.ERROR);
    }
}

package com.csdn.demo1.global;
import lombok.Getter;
@Getter //只要getter方法，无需setter
public class APIException extends RuntimeException {
    private int code;
    private String msg;
    public APIException() {
        this(1001, "接口错误");
    }
    public APIException(String msg) {
        this(1001, msg);
    }
    public APIException(int code, String msg) {
        super(msg);
        this.code = code;
        this.msg = msg;
    }
}

//自定义的全局异常
@ExceptionHandler(APIException.class)
public String APIExceptionHandler(APIException e) {
    return e.getMsg();
}

@Getter
public enum ResultCode {
    SUCCESS(1000, "操作成功"),
    FAILED(1001, "响应失败"),
    VALIDATE_FAILED(1002, "参数校验失败"),
    ERROR(5000, "未知错误");
    private int code;
    private String msg;
    ResultCode(int code, String msg) {
        this.code = code;
        this.msg = msg;
    }
}

package com.csdn.demo1.global;
import lombok.Getter;
@Getter
public class ResultVO<T> {
    /**
     * 状态码，比如1000代表响应成功
     */
    private int code;
    /**
     * 响应信息，用来说明响应情况
     */
    private String msg;
    /**
     * 响应的具体数据
     */
    private T data;
    public ResultVO(T data) {
        this(ResultCode.SUCCESS, data);
    }
    public ResultVO(ResultCode resultCode, T data) {
        this.code = resultCode.getCode();
        this.msg = resultCode.getMsg();
        this.data = data;
    }
}

@RestControllerAdvice
public class ExceptionControllerAdvice {
    @ExceptionHandler(APIException.class)
    public ResultVO<String> APIExceptionHandler(APIException e) {
        // 注意哦，这里传递的响应码枚举
        return new ResultVO<>(ResultCode.FAILED, e.getMsg());
    }
    @ExceptionHandler(MethodArgumentNotValidException.class)
    public ResultVO<String> MethodArgumentNotValidExceptionHandler(MethodArgumentNotValidException e) {
        ObjectError objectError = e.getBindingResult().getAllErrors().get(0);
        // 注意哦，这里传递的响应码枚举
        return new ResultVO<>(ResultCode.VALIDATE_FAILED, objectError.getDefaultMessage());
    }
}

@GetMapping("/getUser")
public ResultVO<User> getUser() {
    User user = new User();
    user.setId(1L);
    user.setAccount("12345678");
    user.setPassword("12345678");
    user.setEmail("123@qq.com");
    return new ResultVO<>(user);
}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class Msg {
    //状态码
    private int code;
    //提示信息
    private String msg;
    //用户返回给浏览器的数据
    private Map<String,Object> data = new HashMap<>();
    public static Msg success() {
        Msg result = new Msg();
        result.setCode(200);
        result.setMsg("请求成功！");
        return result;
    }
    public static Msg fail() {
        Msg result = new Msg();
        result.setCode(400);
        result.setMsg("请求失败！");
        return result;
    }
    public static Msg fail(String msg) {
        Msg result = new Msg();
        result.setCode(400);
        result.setMsg(msg);
        return result;
    }
    public Msg(ReturnResult returnResult){
        code = returnResult.getCode();
        msg = returnResult.getMsg();
    }
    public Msg add(String key,Object value) {
        this.getData().put(key, value);
        return this;
    }
}

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD}) // 表明该注解只能放在方法上
public @interface NotResponseBody {
}

@GetMapping("/getUser")
//@NotResponseBody  //是否绕过数据统一响应开关
public User getUser() {
    User user = new User();
    user.setId(1L);
    user.setAccount("12345678");
    user.setPassword("12345678");
    user.setEmail("123@qq.com");
    // 注意哦，这里是直接返回的User类型，并没有用ResultVO进行包装
    return user;
}

@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface ApiVersion {
    // 默认接口版本号1.0开始，这里我只做了两级，多级可在正则进行控制
    String value() default "1.0";
}

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