Google Picasa API初体验

Google Picasa是一个在线的相册系统，他提供了很多API，我们可以对相册进行操作，下面就是一个简单的获得一个用户所有相册，并把相册里面所有的图片显示出来，页面我也没有做什么美化，在初步研究之后，发现它的API的功能还比较强大，以后有时间了再看看其他的功能。源代码和.war文件都太大了，上传两个图片看看。。




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import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;

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

import com.google.gdata.client.photos.PicasawebService;
import com.google.gdata.data.Link;
import com.google.gdata.data.photos.AlbumEntry;
import com.google.gdata.data.photos.AlbumFeed;
import com.google.gdata.data.photos.GphotoEntry;
import com.google.gdata.data.photos.PhotoEntry;
import com.google.gdata.data.photos.UserFeed;
import com.google.gdata.util.AuthenticationException;
import com.google.gdata.util.ServiceException;

public class PicasaServlet extends HttpServlet {

	/**
	 * This is a serial version generated by eclipse.
	 */
	private static final long serialVersionUID = -6737329335179440491L;

	/**
	 * This is the api prefix of the goold picasa forum.
	 */
	private static final String API_PREFIX = "http://picasaweb.google.com/data/feed/api/user/";

	/**
	 * This method is to deal with the HTTP GET request.
	 * 
	 * @param request
	 *            The HttPServletRequest object.
	 * @param response
	 *            The HttpServletResponse object.
	 * @throws ServletException
	 *             Throws servlet exception if encounters some server errors.
	 * @throws IOException
	 *             Throws IOException if encounter some io write/read errors.
	 */
	@Override
	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		doPost(request, response);
	}

	/**
	 * This method is to deal with the HTTP Post request. Download the image and
	 * corresponding thumbnails image with emailAddress and password
	 * authentication, and save it to "/image" folder, this can be displayed
	 * directly in the client.
	 * 
	 * @param request
	 *            The HttPServletRequest object.
	 * @param response
	 *            The HttpServletResponse object.
	 * @throws ServletException
	 *             Throws servlet exception if encounters some server errors.
	 * @throws IOException
	 *             Throws IOException if encounter some io write/read errors.
	 */
	@SuppressWarnings("deprecation")
	@Override
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		String emailAddress = request.getParameter("emailAddress");
		String password = request.getParameter("password");
		String realPath = request.getRealPath("/image");
		Map<String, List<String>> albumPhotos = generatePhoto(emailAddress,
				password, realPath);
		request.setAttribute("albumPhotos", albumPhotos);
		request.getRequestDispatcher("/result.jsp").forward(request, response);
	}
	
	/**
	 * This method is to get the album, and all the photo's name and thumbnail
	 * format name, and the photo's description.
	 * 
	 * @param emailAddress
	 *            The email address which you used to authenticated.
	 * @param password
	 *            The password which you used to authenticated.
	 * @param realPath
	 *            The realPath you want to save the images.
	 * @return Map<String,List<Sring>> which represents the album and all the
	 *         photos in that album. It always have the following format.
	 *         albumName: test.png i_test.png This is the image's description.
	 * @throws IOException
	 *             Throws IOException if encounter some io write/read errors.
	 */
	public Map<String, List<String>> generatePhoto(String emailAddress,
			String password, String realPath) throws IOException {
		if (emailAddress != null && password != null) {
			try {
				PicasawebService picasaService = buildPicasaWebService(
						"Picasa", emailAddress, password);
				List<AlbumEntry> albums = getAlbums(picasaService, emailAddress);
				Map<String, List<String>> albumPhotos = new Hashtable<String, List<String>>();
				for (AlbumEntry albumEntry : albums) {
					List<PhotoEntry> photoEntrys = getPhotos(picasaService,
							albumEntry);
					if (photoEntrys.size() > 0) {
						List<String> photos = new ArrayList<String>();
						for (PhotoEntry photoEntry : photoEntrys) {
							String thumbnailsName = writeImage(photoEntry
									.getMediaThumbnails().get(0).getUrl(),
									realPath, false);
							String originalName = writeImage(photoEntry
									.getMediaContents().get(0).getUrl(),
									realPath, true);
							photos.add(thumbnailsName);
							photos.add(originalName);
							photos.add(photoEntry.getDescription()
									.getPlainText());
						}
						albumPhotos.put(albumEntry.getName(), photos);
					}
				}
				return albumPhotos;
			} catch (AuthenticationException e) {
				e.printStackTrace();
			} catch (ServiceException e) {
				e.printStackTrace();
			}
		}
		return new Hashtable<String, List<String>>();
	}

	/**
	 * This is method is to build a PicasawebService object using the
	 * emailAddress and password, and the appName.
	 * 
	 * @param appName
	 *            The appname you want to set, in this program we set it
	 *            "picasa"
	 * @param emailAddress
	 *            The email address of you used to authenticated.
	 * @param password
	 *            The password you used to authenticated.
	 * @return The PicasawebService object.
	 * @throws AuthenticationException
	 *             If there exist some authentication exception occur.
	 */
	public PicasawebService buildPicasaWebService(String appName,
			String emailAddress, String password)
			throws AuthenticationException {
		PicasawebService picasaService = new PicasawebService(appName);
		picasaService.setUserCredentials(emailAddress, password);
		return picasaService;
	}


	/**
	 * This method is to extract a user's album.
	 * 
	 * @param picasaService
	 *            The picasawebService object, we use this object to get the
	 *            user's feed.
	 * @param username
	 *            The user name which we want to get the all the album.
	 * @return A list of AlbumEntrys.
	 * @throws IOException
	 *             There is some write/read exception occured.
	 * @throws ServiceException
	 *             This is some service exception occur, for example, the wrong
	 *             URL
	 */
	@SuppressWarnings("unchecked")
	public List<AlbumEntry> getAlbums(PicasawebService picasaService,
			String username) throws IOException, ServiceException {

		String albumUrl = API_PREFIX + username;
		UserFeed userFeed = picasaService.getFeed(new URL(albumUrl),
				UserFeed.class);

		List<GphotoEntry> entries = userFeed.getEntries();
		List<AlbumEntry> albums = new ArrayList<AlbumEntry>();
		for (GphotoEntry entry : entries) {
			GphotoEntry adapted = entry.getAdaptedEntry();
			if (adapted instanceof AlbumEntry) {
				albums.add((AlbumEntry) adapted);
			}
		}
		return albums;
	}

	/**
	 * This method is to extract all the photos from a particular album.
	 * 
	 * @param picasaService
	 *            The picasawebService object, we use this object to get the
	 *            user's feed.
	 * @param album
	 *            The AlbumEntry object which you want to get all the photos
	 *            from it.
	 * @return A list of PhotoEntry object.
	 * @throws IOException
	 *             There is some write/read exception occured.
	 * @throws ServiceException
	 *             This is some service exception occur, for example, the wrong
	 *             URL
	 */
	@SuppressWarnings("unchecked")
	public List<PhotoEntry> getPhotos(PicasawebService picasaService,
			AlbumEntry album) throws IOException, ServiceException {

		String feedHref = getLinkByRel(album.getLinks(), Link.Rel.FEED);
		AlbumFeed albumFeed = picasaService.getFeed(new URL(feedHref),
				AlbumFeed.class);

		List<GphotoEntry> entries = albumFeed.getEntries();
		List<PhotoEntry> photos = new ArrayList<PhotoEntry>();
		for (GphotoEntry entry : entries) {
			GphotoEntry adapted = entry.getAdaptedEntry();
			if (adapted instanceof PhotoEntry) {
				photos.add((PhotoEntry) adapted);
			}
		}
		return photos;
	}
	

	/**
	 * This method is a helper method, is to get the href from with a link's
	 * name from the corresponding links collection.
	 * 
	 * @param links
	 *            The Link collection you want to elect from.
	 * @param relValue
	 *            The corresponding value.
	 * @return The real link's href value.
	 */
	public String getLinkByRel(List<Link> links, String relValue) {
		for (Link link : links) {
			if (relValue.equals(link.getRel())) {
				return link.getHref();
			}
		}
		throw new IllegalArgumentException("Missing " + relValue + " link.");
	}
	

	/**
	 * This method is to write the urlAddress's image to the server's "/image"
	 * folder, and if it is the thumbnail, we just directly add a "i_" prefix to
	 * distinguish,
	 * 
	 * @param urlAddress
	 *            The image URL address, it is a String object.
	 * @param realPath
	 *            The real path of "/image" folder, in that path you want to
	 *            save this image.
	 * @param isThumbnail
	 *            Whether the image is thumbnail.
	 * @return The filename of the image, if it is thumbnail manner.
	 */
	public String writeImage(String urlAddress, String realPath,
			boolean isThumbnail) {
		try {
			URL url = new URL(urlAddress);
			BufferedInputStream bis = new BufferedInputStream(url.openStream());
			String fileName = getFileName(urlAddress, isThumbnail);
			byte[] bytes = new byte[1024];
			OutputStream bos = new FileOutputStream(new File(realPath + "\\"
					+ fileName));
			int len;
			while ((len = bis.read(bytes)) > 0) {
				bos.write(bytes, 0, len);
			}
			bis.close();
			bos.flush();
			bos.close();
			return fileName;
		} catch (MalformedURLException e) {
			e.printStackTrace();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return "";
	}

	/**
	 * This method is to get the file name from the URL address, and if it is
	 * thumbnail, add a "i_" prefix to distinguish.
	 * 
	 * @param urlAddress
	 *            The URL address that contains the real image address.
	 * @param isThumbnail
	 *            Whether this image is thumbnail
	 * @return The formated filename of this image represented by the URL
	 *         address.
	 */
	public String getFileName(String urlAddress, boolean isThumbnail) {
		int lastURLSeparater = urlAddress.lastIndexOf("/");
		if (isThumbnail) {
			return urlAddress.substring(lastURLSeparater + 1);
		} else {
			return "i_" + urlAddress.substring(lastURLSeparater + 1);
		}
	}
}

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
	"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Input the emailAddress and password</title>
</head>
<body>
<form action="servlet/picasaServlet" method="post">
	<label>Input emailAddress:</label>
	<input type="text" name="emailAddress" />
	<label>Input password:</label>
	<input type="password"" name="password" />
	<input type="submit" value="submit">
</form>
</body>
</html>

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<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ page import="java.util.*" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
	"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Input the emailAddress and password</title>
</head>
<body>
	
	<%
		Map<String,List<String>> albumPhotos = 
			(Map<String,List<String>>)request.getAttribute("albumPhotos");
		for(Iterator<String> it = albumPhotos.keySet().iterator(); it.hasNext();){
			String albumName = it.next();
			List<String> photos = albumPhotos.get(albumName);
	%>
		albumName:<%=albumName%><br>
		<%for(int i = 0; i < photos.size(); i+=3){%>
		Thumbnails: <img alt="" src="<%=request.getContextPath()%>/image/<%=photos.get(i)%>"><br>
		Original: <img alt="" src="<%=request.getContextPath()%>/image/<%=photos.get(i+1)%>"><br>
		Description: <%=photos.get(i+2)%>
		
	<%
			}
		}
	%>
	
</body>
</html>

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评论

3 楼 ankang2577 2010-12-11  

楼主留个能不能给我讲一下，在eclipse中如何配置picasa的API，加我QQ号771006587，谢谢了

2 楼 shjie5246 2009-05-04  

我做的时候缺少类

1 楼 shjie5246 2009-05-04  

能把相关的jar包贡献下吗,谢谢了.