imageservice.java

Tapestry的一个练习例子

package com.ttdev.updown;

import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletResponse;

import org.apache.hivemind.ApplicationRuntimeException;
import org.apache.tapestry.IRequestCycle;
import org.apache.tapestry.engine.IEngineService;
import org.apache.tapestry.engine.ILink;
import org.apache.tapestry.services.Infrastructure;
import org.apache.tapestry.services.LinkFactory;

public class ImageService implements IEngineService {
	public String getName() {
		return "image";
	}

	private LinkFactory linkFactory;

	public void setLinkFactory(LinkFactory linkFactory) {
		this.linkFactory = linkFactory;
	}

	private Infrastructure infrastructure;

	public void setInfrastructure(Infrastructure infrastructure) {
		this.infrastructure = infrastructure;
	}

	public ILink getLink(boolean post, Object parameter) {
		String imageId = (String) ((Object[]) parameter)[0];
		Map parameters = new HashMap();
		parameters.put("imageId", imageId);
		return linkFactory.constructLink(this, post, parameters, false);
	}

	private HttpServletResponse response;

	public void setResponse(HttpServletResponse response) {
		this.response = response;
	}

	public void service(IRequestCycle cycle) throws IOException {
		int imageId = Integer.parseInt(cycle.getParameter("imageId"));
		byte imageData[] = ImageDB.loadImage(imageId);
		response.setHeader("Content-disposition",
				"attachment; filename=foo.jpg");
		response.setContentType("image/jpeg");
		response.setContentLength(imageData.length);
		try {
			OutputStream out = response.getOutputStream();
			out.write(imageData);
		} catch (IOException e) {
			throw new ApplicationRuntimeException(e);
		}
	}
}