Bug记录——搬用、挪用、使用、借鉴、学习别人SpringBoot工程的二三事

一、前端明明返回了token，检查前端没问题了（就是axios响应拦截有数据，then没数据）

找了半天前端的问题，最后发现，原因是后端ResultHandler的扫包问题

Result实体类

package com.example.demo.entity;

import lombok.Data;

/**
 * 统一返回的数据格式
 * @author sxj
 * @param <T>
 */
@Data
public class Result<T> {
    private Integer code; // 状态码
    private String message; // 状态描述信息
    private T data; // 定义为范型
}

aspect包--ResultHandler

package com.example.demo.aspect;

import com.example.demo.entity.Result;
import com.example.demo.exception.ErrorCode;
import com.example.demo.util.ResultUtil;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.core.MethodParameter;
import org.springframework.http.MediaType;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.lang.Nullable;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;

import java.lang.reflect.AnnotatedElement;
import java.util.Arrays;

/**
 * 按照统一格式返回值
 * @author sxj
 */
@ControllerAdvice(basePackages = "com.example.demo.controller")
public class ResultHandler implements ResponseBodyAdvice {

    private ThreadLocal<ObjectMapper>  mapperThreadLocal = ThreadLocal.withInitial(ObjectMapper::new);

    private static final Class[] annos = {
            RequestMapping.class,
            GetMapping.class,
            PostMapping.class,
            DeleteMapping.class,
            PutMapping.class
    };

    /**
     * 对所有RestController的接口方法进行拦截
     */
    @Override
    public boolean supports(MethodParameter returnType, Class converterType) {
        AnnotatedElement element = returnType.getAnnotatedElement();
        return Arrays.stream(annos).anyMatch(anno -> anno.isAnnotation() && element.isAnnotationPresent(anno));
    }

    @Override
    public Object beforeBodyWrite(@Nullable Object body, MethodParameter returnType, MediaType selectedContentType, Class selectedConverterType, ServerHttpRequest request, ServerHttpResponse response) {
        Object out;
        ObjectMapper mapper = mapperThreadLocal.get();
        response.getHeaders().setContentType(MediaType.APPLICATION_JSON);
        if(body instanceof Result){
            out = body;
        }
        else if (body instanceof ErrorCode){
            ErrorCode errorCode = (ErrorCode) body;
            out = ResultUtil.error(errorCode.getCode(),errorCode.getMessage());
        }
        else if (body instanceof String){
            Result result = ResultUtil.success(body);
            try {
                //因为是String类型，我们要返回Json字符串，否则SpringBoot框架会转换出错
                out = mapper.writeValueAsString(result);
            } catch (JsonProcessingException e) {
                out = ResultUtil.error(ErrorCode.JSON_PARSE_ERROR);
            }
        }
        else{
            out = ResultUtil.success(body);
        }
        return out;
    }
}

总结：每次使用别人的工程时，可以使用idea的edit-->find-->replace in files进行包名替换

二、多看看xml文件吧

使用自己的数据库时，改别人的xml还是要改很多的，一旦不小心就会报错，
例如：
在通用结果映射查询（BaseResultMap）里面明明将user_id映射成了userId
但是仍然错误的使用了user_id <collection column="{userId = user_id}"/>

点击查看代码

<resultMap id="UserVoResult" extends="BaseResultMap" type="com.example.demo.vo.UserVo">
	<collection property="roles" column="{userId = userId}" ofType="com.example.demo.entity.Role" select="com.example.demo.mapper.RoleMapper.listByUserId"/>
</resultMap>