【 通用异常处理 】

场景预设

场景

加入我们做新增商品，需要接收下面的参数：

price：价格
name：名称

然后对数据做简单校验：

• 价格不能为空

新增时，自动生成 ID ，然后随商品对象一起返回

代码

实体类：

package com.leyou.item.pojo;

import lombok.Data;

@Data
public class Item {
    private Integer id;
    private String name;
    private Long price;
}

service：

package com.leyou.item.service;

import com.leyou.item.pojo.Item;
import org.springframework.stereotype.Service;

import java.util.Random;

@Service
public class ItemService {

    public Item saveItem(Item item){
        // 商品新增
        int id = new Random().nextInt(100);
        item.setId(id);
        return item;
    }

}

controller：

package com.leyou.item.web;

import com.leyou.item.pojo.Item;
import com.leyou.item.service.ItemService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("item")
public class ItemController {

    @Autowired
    private ItemService itemService;

    @PostMapping
    public ResponseEntity<Item> saveItem(Item item){
        // 校验商品的价格
        if (item.getPrice() == null){
            return ResponseEntity.status(HttpStatus.BAD_REQUEST).body(null);
        }
        Item item1 = itemService.saveItem(item);
        return ResponseEntity.status(HttpStatus.CREATED).body(item1);
    }

}

测试：

改写：

上述异常是由 SpringMVC 处理的，而我们真正要的是自己处理！

通用的异常处理 —— 放到 ly-common 里面

ExceptionEnum：枚举 异常

package com.leyou.common.enums;

import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;

@Getter
@NoArgsConstructor
@AllArgsConstructor
public enum ExceptionEnum {

    PRICE_CANNOT_BE_NULL(400, "价格不能为空！")
    ;
    private int code;
    private String msg;
}

ExceptionResult：异常结果 定义

package com.leyou.common.vo;

import com.leyou.common.enums.ExceptionEnum;
import lombok.Data;

@Data
public class ExceptionResult {
    private int status;
    private String message;
    private Long timestamp;

    public ExceptionResult(ExceptionEnum em) {
        this.status = em.getCode();
        this.message = em.getMsg();
        this.timestamp = System.currentTimeMillis();
    }
}

LyException：自定义 异常

package com.leyou.common.exception;

import com.leyou.common.enums.ExceptionEnum;
import lombok.AllArgsConstructor;
import lombok.Getter;
import lombok.NoArgsConstructor;

@NoArgsConstructor
@AllArgsConstructor
@Getter
public class LyException extends RuntimeException {

    private ExceptionEnum exceptionEnum;
}

CommonExceptionHandler：定义 通用的异常处理

添加依赖：
不需要指定版本

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
        </dependency>

package com.leyou.common.advice;

import com.leyou.common.exception.LyException;
import com.leyou.common.vo.ExceptionResult;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;

@ControllerAdvice
public class CommonExceptionHandler {

    @ExceptionHandler(LyException.class)
    public ResponseEntity<ExceptionResult> handleException(LyException e){
        return ResponseEntity.status(e.getExceptionEnum().getCode())
                .body(new ExceptionResult(e.getExceptionEnum()));
    }

}

在 ly-item-service 里面依赖 ly-common ：

        <dependency>
            <groupId>com.leyou.common</groupId>
            <artifactId>ly-common</artifactId>
            <version>1.0.0-SNAPSHOT</version>
        </dependency>

改写 ItemController

package com.leyou.item.web;

import com.leyou.common.enums.ExceptionEnum;
import com.leyou.common.exception.LyException;
import com.leyou.item.pojo.Item;
import com.leyou.item.service.ItemService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("item")
public class ItemController {

    @Autowired
    private ItemService itemService;

    @PostMapping
    public ResponseEntity<Item> saveItem(Item item){
        // 校验商品的价格
        if (item.getPrice() == null){
            throw new LyException(ExceptionEnum.PRICE_CANNOT_BE_NULL);
        }
        Item item1 = itemService.saveItem(item);
        return ResponseEntity.status(HttpStatus.CREATED).body(item1);
    }

}

测试：