edu.harvard.i2b2.fhirserver.ws.FileServlet.java Source code

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Here is the source code for edu.harvard.i2b2.fhirserver.ws.FileServlet.java

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/*
 * Copyright (c) 2006-2007 Massachusetts General Hospital 
 * All rights reserved. This program and the accompanying materials 
 * are made available under the terms of the i2b2 Software License v1.0 
 * which accompanies this distribution. 
 * 
 * Contributors:
 *       Kavishwar Wagholikar (kavi)
 *       July 4, 2015
 */

package edu.harvard.i2b2.fhirserver.ws;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URI;
import java.net.URL;
import java.net.URLDecoder;

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

import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * The File servlet for serving from absolute path.
 * @author BalusC
 * @link http://balusc.blogspot.com/2007/07/fileservlet.html
 */
public class FileServlet extends HttpServlet {
    static Logger logger = LoggerFactory.getLogger(FileServlet.class);

    // Constants ----------------------------------------------------------------------------------

    private static final int DEFAULT_BUFFER_SIZE = 10240; // 10KB.

    // Properties ---------------------------------------------------------------------------------

    private String basePath;

    // Actions ------------------------------------------------------------------------------------

    public void init() throws ServletException {

        // Define base path somehow. You can define it as init-param of the servlet.
        try {
            this.basePath = this.getServletContext().getResource("/").toString();
            this.basePath = this.basePath.substring(0, this.basePath.length() - 1);
        } catch (MalformedURLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // In a Windows environment with the Applicationserver running on the
        // c: volume, the above path is exactly the same as "c:\files".
        // In UNIX, it is just straightforward "/files".
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // Get requested file by path info.

        String requestedFile = request.getPathInfo();

        if (requestedFile.equals("/"))
            requestedFile = "/index.html";
        logger.trace("Got request:" + requestedFile);
        logger.trace("basePath:" + this.basePath);
        logger.trace("ffp:" + basePath + requestedFile);

        // Check if file is actually supplied to the request URI.
        //if (requestedFile == null) {
        // Do your thing if the file is not supplied to the request URI.
        // Throw an exception, or send 404, or show default/warning page, or just ignore it.
        //  response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
        //return;
        //}

        // Decode the file name (might contain spaces and on) and prepare file object.
        URL url = new URL(basePath + requestedFile);
        logger.trace("url:" + url);
        File file = FileUtils.toFile(url);
        logger.trace("searching for file:" + file.getAbsolutePath());

        // Check if file actually exists in filesystem.
        if (!file.exists()) {
            // Do your thing if the file appears to be non-existing.
            // Throw an exception, or send 404, or show default/warning page, or just ignore it.
            response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
            return;
        }

        // Get content type by filename.
        String contentType = getServletContext().getMimeType(file.getName());

        // If content type is unknown, then set the default value.
        // For all content types, see: http://www.w3schools.com/media/media_mimeref.asp
        // To add new content types, add new mime-mapping entry in web.xml.
        if (contentType == null) {
            contentType = "application/text";
        }

        // Init servlet response.
        response.reset();
        response.setBufferSize(DEFAULT_BUFFER_SIZE);
        response.setContentType(contentType);
        response.setHeader("Content-Length", String.valueOf(file.length()));
        //  response.setHeader("Content-Disposition", "attachment; filename=\"" + file.getName() + "\"");

        // Prepare streams.
        BufferedInputStream input = null;
        BufferedOutputStream output = null;

        try {
            // Open streams.
            input = new BufferedInputStream(new FileInputStream(file), DEFAULT_BUFFER_SIZE);
            output = new BufferedOutputStream(response.getOutputStream(), DEFAULT_BUFFER_SIZE);

            // Write file contents to response.
            byte[] buffer = new byte[DEFAULT_BUFFER_SIZE];
            int length;
            while ((length = input.read(buffer)) > 0) {
                output.write(buffer, 0, length);
            }
        } finally {
            // Gently close streams.
            close(output);
            close(input);
        }
    }

    // Helpers (can be refactored to public utility class) ----------------------------------------

    private static void close(Closeable resource) {
        if (resource != null) {
            try {
                resource.close();
            } catch (IOException e) {
                // Do your thing with the exception. Print it, log it or mail it.
                e.printStackTrace();
            }
        }
    }

}