/error处理

 

1 BasicErrorController

　　1.1 简述

　　　　SpringMVC框架在出现错误时有一个默认的错误请求 /error；出现异常之后执行/error请求之前框架会判断出现异常的请求类型，然后根据请求类型判断是返回一个HTML页面还是JSON格式的错误信息

　　1.2 源码分析

　　　　BasicErrorController主要处理 /error 请求，该类中有两个处理 /error 请求的方法，分别是 errorHtml 和 error，前者返回的是HTML页面后者返回的是JSON格式的数据

　　　　技巧01：如果是浏览器发出的请求出现异常后跳转到 /error 就会执行 errorHtml，然后返回一个HTML页面

　　　　技巧02：如果是其他客户端发出请求出现异常后跳转到 /error 就会执行 error ，然后返回一个JSON格式数据

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by Fernflower decompiler)
//

package org.springframework.boot.autoconfigure.web.servlet.error;

import java.util.Collections;
import java.util.List;
import java.util.Map;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.boot.autoconfigure.web.ErrorProperties;
import org.springframework.boot.autoconfigure.web.ErrorProperties.IncludeStacktrace;
import org.springframework.boot.web.servlet.error.ErrorAttributes;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.stereotype.Controller;
import org.springframework.util.Assert;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.servlet.ModelAndView;

@Controller
@RequestMapping({"${server.error.path:${error.path:/error}}"})
public class BasicErrorController extends AbstractErrorController {
    private final ErrorProperties errorProperties;

    public BasicErrorController(ErrorAttributes errorAttributes, ErrorProperties errorProperties) {
        this(errorAttributes, errorProperties, Collections.emptyList());
    }

    public BasicErrorController(ErrorAttributes errorAttributes, ErrorProperties errorProperties, List<ErrorViewResolver> errorViewResolvers) {
        super(errorAttributes, errorViewResolvers);
        Assert.notNull(errorProperties, "ErrorProperties must not be null");
        this.errorProperties = errorProperties;
    }

    public String getErrorPath() {
        return this.errorProperties.getPath();
    }

    @RequestMapping(
        produces = {"text/html"}
    )
    public ModelAndView errorHtml(HttpServletRequest request, HttpServletResponse response) {
        HttpStatus status = this.getStatus(request);
        Map<String, Object> model = Collections.unmodifiableMap(this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.TEXT_HTML)));
        response.setStatus(status.value());
        ModelAndView modelAndView = this.resolveErrorView(request, response, status, model);
        return modelAndView != null ? modelAndView : new ModelAndView("error", model);
    }

    @RequestMapping
    @ResponseBody
    public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
        Map<String, Object> body = this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.ALL));
        HttpStatus status = this.getStatus(request);
        return new ResponseEntity(body, status);
    }

    protected boolean isIncludeStackTrace(HttpServletRequest request, MediaType produces) {
        IncludeStacktrace include = this.getErrorProperties().getIncludeStacktrace();
        if (include == IncludeStacktrace.ALWAYS) {
            return true;
        } else {
            return include == IncludeStacktrace.ON_TRACE_PARAM ? this.getTraceParameter(request) : false;
        }
    }

    protected ErrorProperties getErrorProperties() {
        return this.errorProperties;
    }
}

BasicErrorController.java