SpringMVC中的异常处理机制详解

<!--配置基于xml的异常映射-->
    <bean id="simpleMappingExceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
        <property name="exceptionMappings">
            <props>
                <!--key属性指定具体的出错类型，标签体中为对应的出错页面（这个值会拼上前后缀以得到全路径）-->
                <prop key="java.lang.Exception">system-error</prop>
            </props>
        </property>
    </bean>

/**
     * 判断此次请求是否是Ajax请求
     * @param request 此次请求对应的request对象
     * @return true表示是Ajax请求，false表示是普通请求
     */
    public static boolean isAjax(HttpServletRequest request) {
        String accept = request.getHeader("Accept");
        String xRequestHeader = request.getHeader("X-Requested-With");
        return accept != null && accept.contains("application/json")
                ||
                xRequestHeader != null && xRequestHeader.equals("XMLHttpRequest");
    }

package com.wuw.crowd.mvc.config;
import com.google.gson.Gson;
import com.wuw.crowd.exception.LoginFailedException;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.servlet.ModelAndView;
import com.wuw.crowd.util.CrowdUtil;
import com.wuw.crowd.constant.CrowdConstant;
import com.wuw.crowd.util.ResultEntity;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
/**
 * @description: 基于注解的异常处理机制
 * @author: WuW
 * @create: 2022/5/2 18:36
 */
@ControllerAdvice
public class MyExceptionResolver {
    @ExceptionHandler(value = ArithmeticException.class)
    public ModelAndView resolveArithmeticException(HttpServletRequest request, HttpServletResponse response, NullPointerException exception) throws IOException {
        String viewName = "system-error";
        return commonResolve(viewName, exception, request, response);
    }
    @ExceptionHandler(value = NullPointerException.class)
    public ModelAndView resolveNullPointerException(HttpServletRequest request, HttpServletResponse response, NullPointerException exception) throws IOException {
        String viewName = "system-error";
        return commonResolve(viewName, exception, request, response);
    }
    @ExceptionHandler(value = LoginFailedException.class)
    public ModelAndView resolveLoginFailedException(HttpServletRequest request, HttpServletResponse response, LoginFailedException exception) throws IOException {
        String viewName = "admin-login";
        return commonResolve(viewName, exception, request, response);
    }
    /**
     * 抽取异常处理机制的公共部分
     * @param viewName 将要返回到哪个页面
     * @param exception 捕获到的异常信息
     * @param request 请求对象
     * @param response 响应对象
     * @return 返回ModelAndView
     * @throws IOException 响应对象获取输出流时抛出异常
     */
    private ModelAndView commonResolve(String viewName, Exception exception, HttpServletRequest request, HttpServletResponse response) throws IOException {
        boolean ajax = CrowdUtil.isAjax(request);
        // 如果是Ajax请求
        if (ajax) {
            // 创建ResultEntity对象
            ResultEntity<Object> failed = ResultEntity.failed(exception.getMessage());
            Gson gson = new Gson();
            // 将ResultEntity对象转换为JSON字符串
            String s = gson.toJson(failed);
            // 将JSON字符串作为响应体返回给浏览器
            response.getWriter().write(s);
            return null;
        }
        // 如果是普通请求
        ModelAndView modelAndView = new ModelAndView();
        modelAndView.addObject(CrowdConstant.ATTR_NAME_EXCEPTION, exception);
        // 设置对应的视图名称
        modelAndView.setViewName(viewName);
        return modelAndView;
    }
}