100 lines
3.1 KiB
Java
100 lines
3.1 KiB
Java
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Reading from an abstract resource
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package com.ack.web.servlet;
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import java.io.IOException;
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import java.io.InputStream;
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import java.net.URL;
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import java.net.URLConnection;
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import javax.servlet.ServletException;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.http.HttpServlet;
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import javax.servlet.http.HttpServletRequest;
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import javax.servlet.http.HttpServletResponse;
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/**
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*
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* This class demonstrates how to view static resources
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* within a web application. It is a URL based scheme
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* for reading resources within the web application. This
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* makes it a more portable solution than the usual
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* getPathTranslated() technique that deals exclusively
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* with files.
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*
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* This class caters for web applications deployed as WAR
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* files and those that are distributed across machines.
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*
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* Note that this is not a production level implementation
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* and really opens up your web application to anyone. It
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* is only meant as a demonstration of how to use
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* getServletContext().getResource() for reading resources
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* within a web application.
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*
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* Use As Follows:
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* http://<server>:<port>/<web-app>/servlet/<servlet path>/file_to_view
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*
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* For example to view my index.jsp page in my web apps root directory
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*
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* http://localhost:8080/ack/vf/index.jsp
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*
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* where /vf/* is mapped to the com.ack.web.servlet.ReadingFromAnAbstractResource
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*/
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public class ReadingFromAnAbstractResource extends HttpServlet {
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public void doGet( HttpServletRequest req, HttpServletResponse res )
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throws ServletException, IOException {
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ServletOutputStream os = res.getOutputStream();
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res.setContentType( "text/plain" );
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// get the resource
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String resourcePath = req.getPathInfo();
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if( resourcePath == null ) {
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res.sendError( HttpServletResponse.SC_NOT_FOUND );
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return;
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}
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System.out.println( "about to read resource -> " + resourcePath );
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// get resource as a url
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URL resourceUrl = getServletContext().getResource( resourcePath );
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if( resourceUrl == null ) {
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res.sendError( HttpServletResponse.SC_NOT_FOUND );
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return;
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}
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// open connection to resource
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URLConnection con = null;
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try {
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con = resourceUrl.openConnection();
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con.connect();
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}
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catch( IOException ioe ) {
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res.sendError( HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
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"unable to read resource: " + resourcePath );
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}
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// set the actual content type in; must check that its non-null
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String contentType = con.getContentType();
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if( contentType != null ) {
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res.setContentType( contentType );
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}
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// send resource contents back down output stream
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try {
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InputStream is = con.getInputStream();
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byte[] buf = new byte[8096];
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int bytesRead;
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while( ( bytesRead = is.read( buf ) ) != -1 ) {
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os.write( buf, 0, bytesRead );
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}
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}
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catch( IOException ioe ) {
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res.sendError( HttpServletResponse.SC_INTERNAL_SERVER_ERROR,
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"unable to send resource to client: " + resourcePath );
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}
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}
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}
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