Membuat error page sendiri menggunakan JSP-Servlet

Posted: August 18, 2011 in Java Servlet
Tags: , , ,

Di tulisan kali ini saya akan membahas mengenai error-page. Kalian semua tentu tidak asing lagi kan dengan tampilan seperti ini Ya error tersebut dikarenakan tidak ada file bernama gogogo atau url /gogogo belum terdaftar di web.xml kita. Kalau tampilannya seperti itu tentu tidak enak dilihat kan ya?😀 Nah Kita bisa menentukan sendiri tampilan halaman error sesuka hati kita, langkah2nya adalah sebagai berikut :

  • Tentukan jenis error yang akan ditangani
  • Siapkan halaman error yang diinginkan
  • Daftarkan halaman error tersebut beserta kode errornya di file web.xml

Sebagai informasi, tabel di bawah ini adalah daftar error code pada protokol HTTP 1.1

Status Code Associated Message Meaning
100 Continue Continue with partial request. (New in HTTP 1.1)
101 Switching Protocols Server will comply with Upgrade header and change to
different protocol. (New in HTTP 1.1)
200 OK Everything’s fine; document follows for GET and
POST requests. This is the default for
servlets; if you don’t use setStatus, you’ll get this.
201 Created Server created a document; the Location header indicates its URL.
202 Accepted Request is being acted upon, but processing is not completed.
203 Non-Authoritative Information Document is being returned normally, but some of the response
headers might be incorrect since a document copy is being used.
(New in HTTP 1.1)
204 No Content No new document; browser should continue to display previous document.
This is a useful if the user periodically reloads a page and you
can determine that the previous page is already up to date. However,
this does not work for pages that are automatically reloaded via
the Refresh response header or the equivalent
<META HTTP-EQUIV="Refresh" ...> header, since returning
this status code stops future reloading. JavaScript-based
automatic reloading could still work in such a case, though.
205 Reset Content No new document, but browser should reset document view. Used
to force browser to clear CGI form fields. (New in HTTP 1.1)
206 Partial Content Client sent a partial request with a Range header, and server
has fulfilled it. (New in HTTP 1.1)
300 Multiple Choices Document requested can be found several places; they’ll be listed in
the returned document. If server has a preferred choice, it
should be listed in the Location response header.
301 Moved Permanently Requested document is elsewhere, and the URL for it is given in
the Location response header. Browsers should
automatically follow the link to the new URL.
302 Found Similar to 301, except that the new URL should be interpreted as
a temporary replacement, not a permanent one. Note: the message was
“Moved Temporarily” in HTTP 1.0, and the constant in
HttpServletResponse is SC_MOVED_TEMPORARILY,
not SC_FOUND.Very useful header,
since browsers automatically follow the link to the new URL.
This status code is so useful that there is a special method for
it, sendRedirect.
Using
response.sendRedirect(url) has a couple of advantages over
doing response.setStatus(response.SC_MOVED_TEMPORARILY) and
response.setHeader("Location", url). First, it is
easier. Second, with sendRedirect, the servlet automatically builds
a page containing the link (to show to older browsers that don’t
automatically follow redirects). Finally, sendRedirectcan handle relative URLs, automatically translating them
to absolute ones.Note that this status code is sometimes
used interchangeably with 301. For example, if you erroneously ask
for http://host/~user (missing the trailing slash), some servers
will send 301 and others will send 302.Technically, browsers are only
supposed to automatically follow the redirection if the original request
was GET. See the 307 header for details.
303 See Other Like 301/302, except that if the original request was POST,
the redirected document (given in the Location header)
should be retrieved via GET. (New in HTTP 1.1)
304 Not Modified Client has a cached document and
performed a conditional request (usually by supplying an
If-Modified-Since header indicating that it only wants
documents newer than a specified date). Server wants
to tell client that the old, cached document should still be used.
305 Use Proxy Requested document should be retrieved via proxy listed in
Location header. (New in HTTP 1.1)
307 Temporary Redirect This is identical to 302 (“Found” or “Temporarily Moved”). It
was added to HTTP 1.1 since many browsers erroneously followed the redirection
on a 302 response even if the original message was a POST, even though
it really ought to have followed the redirection of a POST request
only on a 303 response. This response is intended to be unambigously
clear: follow redirected GET and POST requests
in the case of 303 responses, only follow the redirection for GETrequests in the case of 307 responses. Note: for some reason there is no
constant in HttpServletResponse corresponding to this status code.
(New in HTTP 1.1)
400 Bad Request Bad syntax in the request.
401 Unauthorized Client tried to access password-protected page without proper authorization.
Response should include a WWW-Authenticate header that the browser would
use to pop up a username/password dialog box, which then comes back
via the Authorization header.
403 Forbidden Resource is not available, regardless of authorization. Often the result
of bad file or directory permissions on the server.
404 Not Found No resource could be found at that address. This is the standard
“no such page” response. This is such a common and useful
response that there is a special method for it in HttpServletResponse:
sendError(message).
The advantage of
sendError over setStatus is that,
with sendError, the server automatically generates an error page
showing the error message.
405 Method Not Allowed The request method (GET, POST, HEAD,
DELETE, PUT, TRACE, etc.) was
not allowed for this particular resource. (New in HTTP 1.1)
406 Not Acceptable Resource indicated generates a MIME type incompatible with that
specified by the client via its Accept header.
(New in HTTP 1.1)
407 Proxy Authentication Required Similar to 401, but proxy server must return a Proxy-Authenticate
header. (New in HTTP 1.1)
408 Request Timeout The client took too long to send the request. (New in HTTP 1.1)
409 Conflict Usually associated with PUT requests; used for situations such
as trying to upload an incorrect version of a file. (New in HTTP 1.1)
410 Gone Document is gone; no forwarding address known. Differs from 404 in
that the document is is known to be permanently gone in this case,
not just unavailable for unknown reasons as with 404.
(New in HTTP 1.1)
411 Length Required Server cannot process request unless client sends a
Content-Length header. (New in HTTP 1.1)
412 Precondition Failed Some precondition specified in the request headers was false.
(New in HTTP 1.1)
413 Request Entity Too Large The requested document is bigger than the server wants to
handle now. If the server thinks it can handle it later, it
should include a Retry-After header.
(New in HTTP 1.1)
414 Request URI Too Long The URI is too long. (New in HTTP 1.1)
415 Unsupported Media Type Request is in an unknown format. (New in HTTP 1.1)
416 Requested Range Not Satisfiable Client included an unsatisfiable Range header in request.
(New in HTTP 1.1)
417 Expectation Failed Value in the Expect request header could not be met.
(New in HTTP 1.1)
500 Internal Server Error Generic “server is confused” message. It is often the result
of CGI programs or (heaven forbid!) servlets that crash or
return improperly formatted headers.
501 Not Implemented Server doesn’t support functionality to fulfill request. Used,
for example, when client issues command like PUT that server
doesn’t support.
502 Bad Gateway Used by servers that act as proxies or gateways; indicates that initial
server got a bad response from the remote server.
503 Service Unavailable Server cannot respond due to maintenance or overloading. For example,
a servlet might return this header if some thread or database connection
pool is currently full. Server
can supply a Retry-After header.
504 Gateway Timeout Used by servers that act as proxies or gateways; indicates that initial
server didn’t get a response from the remote server in time.
(New in HTTP 1.1)
505 HTTP Version Not Supported Server doesn’t support version of HTTP indicated in request line.
(New in HTTP 1.1)

Sekarang langsung saja buat sebuah new java web project menggunakan netbeans kalian. Lalu buat sebuah file errorPage.jsp berikut

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <div align="center">
        <font face="Comic Sans MS" size="8" color="RED">
            ERROR
        </font>
        </div>
        <hr>

        <h4 align="center">
           <font face="Times New Roman" size="5" color="BLUE">
            Sorry, File / Resource not found.
           </font>
        </h4>
        <hr>
    </body>
</html>
 

Kemudian daftarkan file errorPage.jsp tersebut sebagai sebuah error page di web.xml.

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    <session-config>
        <session-timeout>
            30
        </session-timeout>
    </session-config>
    <welcome-file-list>
        <welcome-file>index.jsp</welcome-file>
    </welcome-file-list>

    <error-page>
        <error-code>404</error-code>
        <location>/errorPage.jsp</location>
    </error-page>

</web-app>
 

Pada contoh di atas saya hanya mendaftarkan 1 jenis error saja, kalian bisa menambahkan jenis error yang kalian kehendaki sebanyak-banyaknya. Sebagai informasi, tidak hanya error code saja yang bisa kalian masukkan ke <error-page>, suatu exception juga bisa kalian masukkan ke dalamnya. Contohnya

  <error-page>
        <exception-type>java.lang.NumberFormatException</exception-type>
        <location>/errorPage.jsp</location>
    </error-page>

Maka jika terjadi suatu NumberFormatException akan dilemparkan ke halaman errorPage.jsp juga. Sekarang cobalah jalankan project kalian, lalu tambahkan gogogo atau sembarang kalimat di akhir url kalian dan enter, kemudian lihat hasilnya akan menjadi seperti ini

Atau kalian juga bisa melakukan redirect langsung di file jsp, apabila di page tersebut terjadi error atau exception. Caranya sangat mudah, di file jsp kalian tinggal menambahkan sintaks berikut di baris pertamanya

<%@page errorPage="errorPage.jsp" %> 

. Untuk lebih jelasnya, cobalah buat suatu file coba.jsp berikut

<%@page errorPage="errorPage.jsp" %>
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
   "http://www.w3.org/TR/html4/loose.dtd">

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>JSP Page</title>
    </head>
    <body>
        <%
            String x ="maniak java";
            int y = Integer.parseInt(x);
        %>
    </body>
</html>
 

Lalu jalankan file coba.jsp di atas. Sudah pasti akan terjadi exception kan, nah maka errornya tidak akan langsung ditampilkan melainkan akan langsung diredirect ke file errorPage.jsp

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