一、统一表现层返回值
根据我们不同的处理方法,返回的数据格式都会不同,例如添加只返回true|false,删除同理,而查询却返回数据。
Result类
为此我们封装一个result类来用于表现层的返回。
public class Result {//描述统一格式中的数据private Object data;//描述统一格式中的编码,用于区分操作,可以简化配置0或1表示成功失败private Integer code;//描述统一格式中的消息,可选属性private String msg;public Result() {}public Result(Integer code,Object data) {this.data = data;this.code = code;}public Result(Integer code, Object data, String msg) {this.data = data;this.code = code;this.msg = msg;}public Object getData() {return data;}public void setData(Object data) {this.data = data;}public Integer getCode() {return code;}public void setCode(Integer code) {this.code = code;}public String getMsg() {return msg;}public void setMsg(String msg) {this.msg = msg;}
}
Code类
Code类不是固定的,是商量好的一种编号,每种编号对应业务操作的不同状态。
public class Code {//Code类的常量设计也不是固定的,可以根据需要自行增减。public static final Integer SAVE_OK = 20011;public static final Integer DELETE_OK = 20021;public static final Integer UPDATE_OK = 20031;public static final Integer GET_OK = 20041;public static final Integer SAVE_ERR = 20010;public static final Integer DELETE_ERR = 20020;public static final Integer UPDATE_ERR = 20030;public static final Integer GET_ERR = 20040;
}
BookController类
//统一每一个控制器方法返回值
@RestController
@RequestMapping("/books")
public class BookController {@Autowiredprivate BookService bookService;@PostMappingpublic Result save(@RequestBody Book book) {boolean flag = bookService.save(book);return new Result(flag ? Code.SAVE_OK:Code.SAVE_ERR,flag);}@PutMappingpublic Result update(@RequestBody Book book) {boolean flag = bookService.update(book);return new Result(flag ? Code.UPDATE_OK:Code.UPDATE_ERR,flag);}@DeleteMapping("/{id}")public Result delete(@PathVariable Integer id) {boolean flag = bookService.delete(id);return new Result(flag ? Code.DELETE_OK:Code.DELETE_ERR,flag);}@GetMapping("/{id}")public Result getById(@PathVariable Integer id) {Book book = bookService.getById(id);Integer code = book != null ? Code.GET_OK : Code.GET_ERR;String msg = book != null ? "" : "数据查询失败,请重试!";return new Result(code,book,msg);}@GetMappingpublic Result getAll() {List<Book> bookList = bookService.getAll();Integer code = bookList != null ? Code.GET_OK : Code.GET_ERR;String msg = bookList != null ? "" : "数据查询失败,请重试!";return new Result(code,bookList,msg);}
}
对应效果
二、异常处理
对于Dao层(数据层),Service层(服务层),Controller(业务控制层)等,所抛出的异常应该统一到业务控制层来处理。
1.封装异常处理器类
@RestControllerAdvice注解可以声明一个类为异常处理器类
@ExceptionHandler注解是定义当前方法用于处理哪一种异常,通过形参可以把异常传进来
2. 项目中的异常
自定义异常都要继承RuntimeException这个类,这个类的父类是Exception,这个类是运行异常类,碰到了自动往业务层传递异常。
BusinessException 自定义业务异常类
//自定义异常处理器,用于封装异常信息,对异常进行分类
public class BusinessException extends RuntimeException{private Integer code;public Integer getCode() {return code;}public void setCode(Integer code) {this.code = code;}
//自动实现的构造方法有很多,只不过这两种实用public BusinessException(Integer code, String message) {super(message);this.code = code;}public BusinessException(Integer code, String message, Throwable cause) {super(message, cause);this.code = code;}
}
SystemException 自定义系统异常类
//自定义异常处理器,用于封装异常信息,对异常进行分类
public class SystemException extends RuntimeException{private Integer code;public Integer getCode() {return code;}public void setCode(Integer code) {this.code = code;}public SystemException(Integer code, String message) {super(message);this.code = code;}public SystemException(Integer code, String message, Throwable cause) {super(message, cause);this.code = code;}}
Code类的补充
public static final Integer SYSTEM_ERR = 50001;public static final Integer SYSTEM_TIMEOUT_ERR = 50002;public static final Integer SYSTEM_UNKNOW_ERR = 59999;public static final Integer BUSINESS_ERR = 60002;
异常控制类-ProjectExceptionAdvice
拦截并处理异常
//@RestControllerAdvice用于标识当前类为REST风格对应的异常处理器
@RestControllerAdvice
public class ProjectExceptionAdvice {//@ExceptionHandler用于设置当前处理器类对应的异常类型@ExceptionHandler(SystemException.class)public Result doSystemException(SystemException ex){//记录日志//发送消息给运维//发送邮件给开发人员,ex对象发送给开发人员return new Result(ex.getCode(),null,ex.getMessage()); //规范返回结果}@ExceptionHandler(BusinessException.class)public Result doBusinessException(BusinessException ex){return new Result(ex.getCode(),null,ex.getMessage());}//除了自定义的异常处理器,保留对Exception类型的异常处理,用于处理非预期的异常@ExceptionHandler(Exception.class)public Result doOtherException(Exception ex){//记录日志//发送消息给运维//发送邮件给开发人员,ex对象发送给开发人员return new Result(Code.SYSTEM_UNKNOW_ERR,null,"系统繁忙,请稍后再试!");}
}