Question

的web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0">
  <display-name>ServletExceptionHandling</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
  </welcome-file-list>

  <error-page>
    <error-code>404</error-code>
    <location>/AppExceptionHandler</location>
  </error-page>

  <error-page>
  <exception-type>javax.servlet.ServletException</exception-type>
  <location>/AppExceptionHandler</location>
  </error-page>

  <error-page>
  <exception-type>java.lang.Throwable</exception-type>
  <location>/AppExceptionHandler</location>
</error-page>
</web-app>

MyExceptionServlet.java

package com.journaldev.servlet.exception;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/MyExceptionServlet")
public class MyExceptionServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        throw new ServletException("GET method is not supported.");
    }

}

AppExceptionHandler.java

package com.journaldev.servlet.exception;

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet("/AppExceptionHandler")
public class AppExceptionHandler extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processError(request, response);
    }

    protected void doPost(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        processError(request, response);
    }

    private void processError(HttpServletRequest request,
            HttpServletResponse response) throws IOException {
        // Analyze the servlet exception
        Throwable throwable = (Throwable) request
                .getAttribute("javax.servlet.error.exception");
        Integer statusCode = (Integer) request
                .getAttribute("javax.servlet.error.status_code");
        String servletName = (String) request
                .getAttribute("javax.servlet.error.servlet_name");
        if (servletName == null) {
            servletName = "Unknown";
        }
        String requestUri = (String) request
                .getAttribute("javax.servlet.error.request_uri");
        if (requestUri == null) {
            requestUri = "Unknown";
        }

        // Set response content type
          response.setContentType("text/html");

          PrintWriter out = response.getWriter();
          out.write("<html><head><title>Exception/Error Details</title></head><body>");
          if(statusCode != 500){
              out.write("<h3>Error Details</h3>");
              out.write("<strong>Status Code</strong>:"+statusCode+"<br>");
              out.write("<strong>Requested URI</strong>:"+requestUri);
          }
          else
          {
              out.write("<h3>Exception Details</h3>");
              out.write("<ul><li>Servlet Name:"+servletName+"</li>");
              out.write("<li>Exception Name:"+throwable.getClass().getName()+"</li>");
              out.write("<li>Requested URI:"+requestUri+"</li>");
              out.write("<li>Exception Message:"+throwable.getMessage()+"</li>");
              out.write("</ul>");
          }

          out.write("<br><br>");
          out.write("<a href=\"index.html\">Home Page</a>");
          out.write("</body></html>");
    }
}

1）我面临的问题是我没有进入Servlet AppExceptionHandler中的processError方法，因为我无法在前端看到异常。

所以请告诉我在哪里犯了错误。

关于servlet Exception

0 个答案: