resizemanager.java

来自「MyUploader 是一款使用 http 协议(RFC 1867)用于上传文件」· Java 代码 · 共 180 行

/*
 * Copyright 2006-2007 JavaAtWork All rights reserved.
 * Use is subject to license terms.
 */
package javaatwork.myuploader.utils;

import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;

import javaatwork.myuploader.net.HTTPUploadTask;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;

/**
 * Class who is responsible for creating a scaled instance in a 
 * temp directory. The temp directory is the System property
 * "java.io.tmpdir".
 * 
 * @author Johannes Postma
 */
public class ResizeManager {

	private File tempDirectory = null;
	private HTTPUploadTask task = null;
	
	/**
	 * Creates a new Resizer.
	 * 
	 * @throws Exception If an error occurred.
	 */
	public ResizeManager(HTTPUploadTask task) throws Exception {
		this.task = task;
		createTempDirectory();
	}
	
	/**
	 * Creates the temp directory.
	 * 
	 * @throws Exception If the temp directory cannot be created.
	 */
	private void createTempDirectory() throws Exception {
		
		File dir = new File(System.getProperty("java.io.tmpdir"));
		tempDirectory = new File(dir, "myuploader-" + System.currentTimeMillis());
		
		if (tempDirectory.exists()) {
			return;
		}
		
		boolean created = tempDirectory.mkdir();
		
		if (created == false) {
			throw new Exception ("Temp directory could not be created");
		}
	}
	
	/**
	 * Deletes the temp directory.
	 */
	public void deleteTempDirectory() {
		
		deleteDirectory(tempDirectory);
	}
	
	/**
	 * Deletes a directory with all the files and subdirectories.
	 * 
	 * @param file The directory.
	 */
	private void deleteDirectory(File file) {
		
		File [] files = file.listFiles();
		
		for (int i = 0; i < files.length; i++) {
			
			if (files[i].isDirectory()) {
				deleteDirectory(files[i]);				
			} else {
				files[i].delete();
			}
		}
		
		file.delete();
	}
	
	/**
	 * Scales an image.
	 * 
	 * @param file The image to be scaled.
	 * @param uploadPath The uploadPath.
	 * @param size The max size.
	 * @return The scaled image.
	 * @throws Exception If an error occurred.
	 */
	public File getScaleImage(File file, String uploadPath, int size, float compressionQuality) throws Exception {
		
		ImageWriter writer = null;
		
		try {
			Image image = (Image) ImageIO.read(file);
	
			int fileSize = (int)file.length();
			
			// divide the fileSize in three parts, this is necessary for a correct progressdialog.
			
			int partOne = fileSize / 3;
			int partTwo = partOne;
			int partThree = fileSize - partOne - partTwo;
				
			// needed for the progressbar
			task.addBytesProcessed(partOne);
			
			int thumbHeight = 0;
			int thumbWidth = 0;
			
			int imageWidth = image.getWidth(null);
			int imageHeight = image.getHeight(null);
			double imageRatio = (double) imageWidth / (double) imageHeight;
			
			if (imageWidth > imageHeight){
				thumbWidth = size;
				thumbHeight = (int)(size / imageRatio);
			} else {
				thumbHeight = size;
				thumbWidth = (int)(size * imageRatio);
			}
			
			// check if the new size is not larger than the original one.
			if (thumbWidth > imageWidth) {
				thumbWidth = imageWidth;
				thumbHeight = imageHeight;
			}
			
			//ImageIcon ic=  new ImageIcon(image.getScaledInstance(thumbWidth, thumbHeight, Image.SCALE_AREA_AVERAGING));
			
			// Draw the scaled image
			BufferedImage thumbImage = new BufferedImage(thumbWidth, thumbHeight, BufferedImage.TYPE_INT_RGB);
			Graphics2D graphics2D = thumbImage.createGraphics();
			graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
			graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null);
			//graphics2D.drawImage(ic.getImage(), 0, 0, thumbWidth, thumbHeight, null);
			
			// needed for the progressbar
			task.addBytesProcessed(partTwo);
			
			File scaleInstance = new File(tempDirectory, uploadPath);
			scaleInstance.mkdirs();
			scaleInstance = new File(scaleInstance, file.getName());
			
			writer = (ImageWriter) ImageIO.getImageWritersByFormatName("JPEG").next();
		    ImageWriteParam param = writer.getDefaultWriteParam();
		  
		    //set quality
		    param.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
		    param.setCompressionQuality(compressionQuality);
		    
		    //write jpeg image
	    	writer.setOutput(ImageIO.createImageOutputStream(scaleInstance));
	    	writer.write(null, new IIOImage(thumbImage, null, null), param);
	    	
	    	// needed for the progressbar
			task.addBytesProcessed(partThree);
	    	
			return scaleInstance;
			
		} finally {
			
			if (writer != null) {
				writer.dispose();
			}
		}
	}
}