spring mvc捕获异常时,如何判断应该返回json还是跳转错误页面

spring mvc捕获异常时,如何判断应该返回json还是跳转错误页面

 在异常捕获handler  BusinessExceptionHandlerAdvice中

 判断控制器的方法是否有ResponseBody注解,如果有,则返回json,

关键问题是:

如何判断控制器的方法是否有ResponseBody注解

我们先看看@ExceptionHandler方法中注入的参数有哪些?

1. ServletResponse.class
2. OutputStream.class
3. Writer.class
4. WebRequest.class
5. ServletRequest.class
6. MultipartRequest.class
7. HttpSession.class
8. Principal.class
9. Locale.class
10. InputStream.class
11. Reader.class

直接获取控制器方法(java.lang.reflect.Method)的计划破灭了,

那么还有没有其他方法呢?

有!通过异常的堆栈 StackTraceElement

那么StackTraceElement有哪些信息呢?

 

所以我们可以通过反射获取控制器方法,然后判断是否有注解ResponseBody.class

具体实现(直接上代码):

package oa.web.controller.handler;

import com.common.bean.BaseResponseDto;
import com.common.bean.exception.LogicBusinessException;
import com.common.util.ReflectHWUtils;
import com.common.util.SystemHWUtil;
import com.common.util.WebServletUtil;
import com.string.widget.util.ValueWidget;
import org.apache.log4j.Logger;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseBody;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;
import java.io.PrintWriter;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Method;
import java.net.URLEncoder;

/**
 * Created by whuanghkl on 3/30/16.
 * 注意使用注解@ControllerAdvice作用域是全局Controller范围
 * 可应用到所有@RequestMapping类或方法上的@ExceptionHandler、@InitBinder、@ModelAttribute，在这里是@ExceptionHandler<br />
 * 用于检测第三方接口,比如bsvc或cia的504,502等异常<br />
 * 这些异常均属于非业务异常,与业务毫无关系,所以单独处理<br />
 * 注意:StoreBusinessException 不要捕获,否则无法被BusinessExceptionHandlerAdvice 截获<br />
 * 注意:传递url中的参数如果可能包含中文一定要URL编码,
 */
@ControllerAdvice
public class BusinessExceptionHandlerAdvice {
    public static Logger logger = Logger.getLogger(BusinessExceptionHandlerAdvice.class);

    /***
     * 判断接口的注解是否是ResponseBody,是,那么返回json,而不是跳转错误页面
     * @param stackTraceElement
     * @return
     */
    public static boolean isControllerAction(StackTraceElement stackTraceElement) {
        String className = stackTraceElement.getClassName();
        if (className.endsWith("Controller")) {
            try {
                Class controllerClass = Class.forName(className);
                Method actionMethod = ReflectHWUtils.getMethod(controllerClass, stackTraceElement.getMethodName(), ResponseBody.class);
                if (null == actionMethod) {
                    return false;
                }
                return true;
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
        return false;
    }

    /***
     * 判断接口的注解是否是ResponseBody,是,那么返回json,而不是跳转错误页面<br />
     * 限制最多循环4次,否则影响性能
     * @param stackTraceElements
     * @return
     */
    public static boolean isControllerAction(StackTraceElement[] stackTraceElements) {
        int length = stackTraceElements.length;
        if (length > 4) {
            length = 4;
        }
        for (int i = 0; i < length; i++) {
            StackTraceElement stackTraceElement = stackTraceElements[i];
            if (isControllerAction(stackTraceElement)) {
                return true;
            }
        }
        return false;
    }
    @ExceptionHandler(LogicBusinessException.class)
//    @RESPONSE_CONTENTTYPE_JSON_UTFStatus(HttpStatus.BAD_REQUEST)
//    @ResponseBody
    public String handleBusinessException(LogicBusinessException ex, HttpSession session, HttpServletRequest request, HttpServletResponse response) {
//        return ClassUtils.getShortName(ex.getClass()) + ex.getMessage();
        logger.error(ex);//{errorCode='1021', errorMessage='用户不在组织的企业客户身份中'}


        logger.error("old url:" + request.getRequestURL());
        logger.error("query string:" + request.getQueryString());
        StackTraceElement[] stackTraceElements = ex.getStackTrace();
       
        if (!ex.isWap()) {
            boolean isControllerAction = isControllerAction(stackTraceElements);
            System.out.println("isControllerAction :" + isControllerAction);
            if (isControllerAction) {
                ex.setWap(true);//表示返回json
            }
        }

        if (ex.isWap() || WebServletUtil.getMobileOsInfo(request).isMobile()) {//如果是手机端
            PrintWriter out = null;
            try {
                out = response.getWriter();
            } catch (IOException e) {
                e.printStackTrace();
            }
            if (ValueWidget.isNullOrEmpty(ex.getResponseBody())) {
                out.print(new BaseResponseDto(ex.getErrorCode(), ex.getErrorMessage()).toJson());
            } else {
                out.print(ex.getResponseBody());
            }
            out.flush();
        } else {
            String redirectUrl = null;
            if (ValueWidget.isNullOrEmpty(ex.getRedirectUrl())) {
                String message = null;
                message = getMessage(ex);
                redirectUrl = "/error.html?error=" + ex.getErrorCode() + "&errorMessage=" + message;
            } else {
                redirectUrl = ex.getRedirectUrl();
            }
            logger.error("redirect url:" + redirectUrl);
            try {
                response.sendRedirect(redirectUrl);
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return null;
    }

    /***
     *
     * @param ex
     * @param message :中文已经经过url 编码
     * @return
     */
    private static String getMessage(LogicBusinessException ex) {
        String message = null;
        if (ValueWidget.isNullOrEmpty(ex.getErrorMessage())) {
            message = SystemHWUtil.EMPTY;
        } else {
            try {
                message = URLEncoder.encode(ex.getErrorMessage(), "UTF-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
        return message;
    }
}

 

简单说明下:

先判断isWap是否为true,如果为true,说明已经手动指定返回json了,那么就不用判断了.

否则才需要通过StackTraceElement判断