Java Tutorial/Servlet/Error Page

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Servlet Error Display

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.*;
public class MyServlet extends HttpServlet {
  public void doGet(HttpServletRequest req, HttpServletResponse res) 
                               throws ServletException, IOException {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();
    String code = null, message = null, type = null;
    Object codeObj, messageObj, typeObj;
    codeObj = req.getAttribute("javax.servlet.error.status_code");
    messageObj = req.getAttribute("javax.servlet.error.message");
    typeObj = req.getAttribute("javax.servlet.error.exception_type");
    if (codeObj != null) code = codeObj.toString();
    if (messageObj != null) message = messageObj.toString();
    if (typeObj != null) type = typeObj.toString();
    String reason = (code != null ? code : type);
    out.println("<HTML>");
    out.println("<HEAD><TITLE>" + reason + ": " + message + "</TITLE></HEAD>");
    out.println("<BODY>");
    out.println("<H1>" + reason + "</H1>");
    out.println("<H2>" + message + "</H2>");
    out.println("<HR>");
    out.println("<I>Error accessing " + req.getRequestURI() + "</I>");
    out.println("</BODY></HTML>");
  }
}





Servlet Error Page

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyServlet extends HttpServlet {
  public void doGet(HttpServletRequest req, HttpServletResponse res)
                               throws ServletException, IOException {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();
    String code = null, message = null, type = null, uri = null;
    Object codeObj, messageObj, typeObj;
    Throwable throwable;
    // Retrieve the three possible error attributes, some may be null
    codeObj = req.getAttribute("javax.servlet.error.status_code");
    messageObj = req.getAttribute("javax.servlet.error.message");
    typeObj = req.getAttribute("javax.servlet.error.exception_type");
    throwable = (Throwable)
      req.getAttribute("javax.servlet.error.exception");
    uri = (String) 
      req.getAttribute("javax.servlet.error.request_uri");
    if (uri == null) {
      uri = req.getRequestURI(); // in case there"s no URI given
    }
    // Convert the attributes to string values
    if (codeObj != null) code = codeObj.toString();
    if (messageObj != null) message = messageObj.toString();
    if (typeObj != null) type = typeObj.toString();
    // The error reason is either the status code or exception type
    String reason = (code != null ? code : type);
    out.println("<HTML>");
    out.println("<HEAD><TITLE>" + reason + ": " + message +
                "</TITLE></HEAD>");
    out.println("<BODY>");
    out.println("<H1>" + reason + "</H1>");
    out.println("<H2>" + message + "</H2>");
    out.println("<PRE>");
    if (throwable != null) {
      throwable.printStackTrace(out);
    }
    out.println("</PRE>");
    out.println("<HR>");
    out.println("<I>Error accessing " + uri + "</I>");
    out.println("</BODY></HTML>");
  }
}


Источник — «http://jexp.ru/index.php?title=Java_Tutorial/Servlet/Error_Page&oldid=4944»