br.com.jhonsapp.util.primefaces.uploaded.ServletUtil Maven / Gradle / Ivy

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package br.com.jhonsapp.util.primefaces.uploaded;

import java.io.IOException;
import java.net.URLDecoder;
import java.nio.file.Files;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import br.com.jhonsapp.repository.concept.Repository;
import br.com.jhonsapp.repository.object.Object;
import br.com.jhonsapp.repository.util.PathUtil;
import br.com.jhonsapp.util.verifier.StringVerifier;

/**
 * Class responsible for manipulating files within the servlet.
 * 
 * @author Jhonathan Camacho
 *
 */
public class ServletUtil {

	/**
	 * Loads a file from a specific repository of an HTTP request into the
	 * servlet.
	 * 
	 * @param repository
	 *            responsible for manipulating files in a specific repository.
	 * 
	 * @param request
	 *            provide request information for HTTP servlets.
	 * 
	 * @param response
	 *            provide HTTP-specific functionality in sending a response.
	 * 
	 * @param servletContext
	 *            represents the servlet context.
	 * @throws IOException
	 *             used when you have an error loading the information.
	 * 
	 */
	public static void loadFile(Repository repository, HttpServletRequest request, HttpServletResponse response,
			ServletContext servletContext) throws IOException {

		if (repository == null)
			throw new IllegalArgumentException("The Repository cannot be null.");

		if (request == null)
			throw new IllegalArgumentException("The HttpServletRequest cannot be null.");

		if (response == null)
			throw new IllegalArgumentException("The HttpServletResponse cannot be null.");

		if (servletContext == null)
			throw new IllegalArgumentException("The ServletContext cannot be null.");

		checkURLInfo(request, response);

		String id = getId(request);

		String folder = getFolder(request);

		Object object = repository.search(folder, id);

		checkIfIsImage(object, response, servletContext);
		
		writeImageToResponse(object, response, servletContext);

	}

	/**
	 * Check if file name is actually supplied to the request URI.
	 * 
	 * @param request
	 *            provide request information for HTTP servlets.
	 * 
	 * @param response
	 *            provide HTTP-specific functionality in sending a response.
	 */
	private static void checkURLInfo(HttpServletRequest request, HttpServletResponse response) throws IOException {
		if (StringVerifier.isBlanck(request.getPathInfo()))
			sendError(response);
	}

	/**
	 * Gets the identifier of the image.
	 * 
	 * @param request
	 *            provide request information for HTTP servlets.
	 * 
	 * @return the identifier.
	 */
	private static String getId(HttpServletRequest request) throws IOException {
		return PathUtil.getId(URLDecoder.decode(request.getPathInfo(), "UTF-8"));
	}

	/**
	 * Gets the path in the directory where the image is located.
	 * 
	 * @param request
	 *            provide request information for HTTP servlets.
	 * 
	 * @return the path in the directory.
	 */
	private static String getFolder(HttpServletRequest request) throws IOException {	
		return PathUtil.getFolder(URLDecoder.decode(request.getPathInfo(), "UTF-8"));
	}

	/**
	 * Send a 404 error.
	 * 
	 * @param response
	 *            provide HTTP-specific functionality in sending a response.
	 */
	private static final void sendError(HttpServletResponse response) throws IOException {
		response.sendError(HttpServletResponse.SC_NOT_FOUND); // 404.
		return;
	}

	/**
	 * Check if file is actually an image (avoid download of other files by
	 * hackers!).
	 * 
	 * @param object
	 *            an abstract representation of the repository object.
	 * 
	 * @param response
	 *            provide HTTP-specific functionality in sending a response.
	 * 
	 * @param servletContext
	 *            represents the servlet context.
	 */
	private static void checkIfIsImage(Object object, HttpServletResponse response, ServletContext servletContext)
			throws IOException {
		
		if (object == null)
			sendError(response);

		String contentType = getContentType(object, servletContext);

		if (contentType == null || !contentType.startsWith("image"))
			sendError(response);
	}

	/**
	 * Gets the content type.
	 * 
	 * @param object
	 *            an abstract representation of the repository object.
	 * 
	 * @param servletContext
	 *            represents the servlet context.
	 * 
	 * @return the content type.
	 */
	private static String getContentType(Object object, ServletContext servletContext) {
		return servletContext.getMimeType(object.getContentsInFile().getName());
	}

	/**
	 * Copying the image into the response.
	 * 
	 * @param object
	 *            an abstract representation of the repository object.
	 * 
	 * @param response
	 *            provide HTTP-specific functionality in sending a response.
	 * 
	 * @param servletContext
	 *            represents the servlet context.
	 * 
	 */
	private static void writeImageToResponse(Object object, HttpServletResponse response, ServletContext servletContext)
			throws IOException {

		response.reset();
		response.setContentType(getContentType(object, servletContext));
		response.setHeader("Content-Length", String.valueOf(object.getContentsInFile().length()));

		Files.copy(object.getContentsInFile().toPath(), response.getOutputStream());
	}

}