AVAJAVA Web Tutorials

(Continued from page 1)

The project's web.xmlW file is shown here. We have a TestServlet mapped to '/test' and a ProgressServlet mapped to '/progress'.

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="file-upload" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
	<servlet>
		<servlet-name>TestServlet</servlet-name>
		<servlet-class>test.TestServlet</servlet-class>
	</servlet>
	<servlet>
		<servlet-name>ProgressServlet</servlet-name>
		<servlet-class>test.ProgressServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>TestServlet</servlet-name>
		<url-pattern>/test</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>ProgressServlet</servlet-name>
		<url-pattern>/progress</url-pattern>
	</servlet-mapping>
</web-app>

The TestServlet class is shown here. This is the class that handles the file upload. It creates a TestProgressListener to monitor the file upload and sticks this in the session.

TestServlet.java

package test;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;

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

import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class TestServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;
//	public static final long MAX_UPLOAD_IN_MEGS = 50;

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
		doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		
		out.println("Hello<br/>");

		boolean isMultipartContent = ServletFileUpload.isMultipartContent(request);
		if (!isMultipartContent) {
			out.println("You are not trying to upload<br/>");
			return;
		}
		out.println("You are trying to upload<br/>");

		FileItemFactory factory = new DiskFileItemFactory();
		ServletFileUpload upload = new ServletFileUpload(factory);
//		upload.setSizeMax(MAX_UPLOAD_IN_MEGS * 1024 * 1024);
		
		TestProgressListener testProgressListener = new TestProgressListener();
		upload.setProgressListener(testProgressListener);

		HttpSession session = request.getSession();
		session.setAttribute("testProgressListener", testProgressListener);
		
		try {
			List<FileItem> fields = upload.parseRequest(request);
			out.println("Number of fields: " + fields.size() + "<br/><br/>");
			Iterator<FileItem> it = fields.iterator();
			if (!it.hasNext()) {
				out.println("No fields found");
				return;
			}
			out.println("<table border=\"1\">");
			while (it.hasNext()) {
				out.println("<tr>");
				FileItem fileItem = it.next();
				boolean isFormField = fileItem.isFormField();
				if (isFormField) {
					out.println("<td>regular form field</td><td>FIELD NAME: " + fileItem.getFieldName() + 
							"<br/>STRING: " + fileItem.getString()
							);
					out.println("</td>");
				} else {
					out.println("<td>file form field</td><td>FIELD NAME: " + fileItem.getFieldName() +
//							"<br/>STRING: " + fileItem.getString() +
							"<br/>NAME: " + fileItem.getName() +
							"<br/>CONTENT TYPE: " + fileItem.getContentType() +
							"<br/>SIZE (BYTES): " + fileItem.getSize() +
							"<br/>TO STRING: " + fileItem.toString()
							);
					out.println("</td>");
				}
				out.println("</tr>");
			}
			out.println("</table>");
		} catch (FileUploadException e) {
			out.println("Error: " + e.getMessage());
			e.printStackTrace();
		}
	}
}

The TestProgressListener class allows us to monitor the progress of the file upload.

TestProgressListener.java

package test;

import org.apache.commons.fileupload.ProgressListener;

public class TestProgressListener implements ProgressListener {

	private long num100Ks = 0;

	private long theBytesRead = 0;
	private long theContentLength = -1;
	private int whichItem = 0;
	private int percentDone = 0;
	private boolean contentLengthKnown = false;

	public void update(long bytesRead, long contentLength, int items) {

		if (contentLength > -1) {
			contentLengthKnown = true;
		}
		theBytesRead = bytesRead;
		theContentLength = contentLength;
		whichItem = items;

		long nowNum100Ks = bytesRead / 100000;
		// Only run this code once every 100K
		if (nowNum100Ks > num100Ks) {
			num100Ks = nowNum100Ks;
			if (contentLengthKnown) {
				percentDone = (int) Math.round(100.00 * bytesRead / contentLength);
			}
			System.out.println(getMessage());
		}
	}

	public String getMessage() {
		if (theContentLength == -1) {
			return "" + theBytesRead + " of Unknown-Total bytes have been read.";
		} else {
			return "" + theBytesRead + " of " + theContentLength + " bytes have been read (" + percentDone + "% done).";
		}

	}

	public long getNum100Ks() {
		return num100Ks;
	}

	public void setNum100Ks(long num100Ks) {
		this.num100Ks = num100Ks;
	}

	public long getTheBytesRead() {
		return theBytesRead;
	}

	public void setTheBytesRead(long theBytesRead) {
		this.theBytesRead = theBytesRead;
	}

	public long getTheContentLength() {
		return theContentLength;
	}

	public void setTheContentLength(long theContentLength) {
		this.theContentLength = theContentLength;
	}

	public int getWhichItem() {
		return whichItem;
	}

	public void setWhichItem(int whichItem) {
		this.whichItem = whichItem;
	}

	public int getPercentDone() {
		return percentDone;
	}

	public void setPercentDone(int percentDone) {
		this.percentDone = percentDone;
	}

	public boolean isContentLengthKnown() {
		return contentLengthKnown;
	}

	public void setContentLengthKnown(boolean contentLengthKnown) {
		this.contentLengthKnown = contentLengthKnown;
	}

}

The ProgressServlet class gets the TestProgressListener reference from the session. In our earlier tutorial, we displayed a friendly status message using testProgressListener.getMessage(). Since now we just want to know the percentage done, we instead call testProgressListener.getPercentDone() and output this to the response.

ProgressServlet.java

package test;

import java.io.IOException;
import java.io.PrintWriter;

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

public class ProgressServlet extends HttpServlet {

	private static final long serialVersionUID = 1L;

	public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {
		doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
		response.setContentType("text/html");
		response.setHeader("Cache-Control", "no-cache");
		
		PrintWriter out = response.getWriter();

		HttpSession session = request.getSession(true);
		if (session == null) {
			out.println("Sorry, session is null"); // just to be safe
			return;
		}

		TestProgressListener testProgressListener = (TestProgressListener) session.getAttribute("testProgressListener");
		if (testProgressListener == null) {
			out.println("Progress listener is null");
			return;
		}

//		out.println(testProgressListener.getMessage());
		out.println(testProgressListener.getPercentDone());

	}
}

(Continued on page 3)