java的圖像縮略方法

本文转载自：

http://www.cnblogs.com/waya/archive/2008/11/04/1326402.html

圖像的縮略代碼

                  //Image image = ImageIO.read(is);

                    Image src=Toolkit.getDefaultToolkit().getImage(file.getPath());//可讀取丟失ICC信息的圖片

                    BufferedImage image=BufferedImageBuilder.toBufferedImage(src);//Image to BufferedImage

                    int w=image.getWidth(null);

                    int h=image.getHeight(null);

                    

                    //縮略圖的size

                    int size=getFileSize(flag);

                    if(size==0)size=h;

                    int nw=size;

                    int nh=(nw*h)/w;

                    if(nh>size){

                        nh=size;

                        nw=(nh*w)/h;

                    }                    

                    BufferedImage tag=new BufferedImage(nw,nh,BufferedImage.TYPE_INT_RGB);

                    tag.getGraphics().drawImage(image.getScaledInstance(nw, nh, Image.SCALE_SMOOTH), 0, 0, null);

                    FileOutputStream out=new FileOutputStream(imageFile);

                    JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(out);

                    encoder.encode(tag);

                    out.close();

 以下是Image轉換BufferedImage代碼

public static BufferedImage toBufferedImage(Image image) {

        if (image instanceof BufferedImage) {

            return (BufferedImage)image;

        }

    

        // This code ensures that all the pixels in the image are loaded

        image = new ImageIcon(image).getImage();

    

        // Determine if the image has transparent pixels; for this method's

        // implementation, see e661 Determining If an Image Has Transparent Pixels

        //boolean hasAlpha = hasAlpha(image);

    

        // Create a buffered image with a format that's compatible with the screen

        BufferedImage bimage = null;

        GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();

        try {

            // Determine the type of transparency of the new buffered image

            int transparency = Transparency.OPAQUE;

           /* if (hasAlpha) {

                transparency = Transparency.BITMASK;

            }*/

    

            // Create the buffered image

            GraphicsDevice gs = ge.getDefaultScreenDevice();

            GraphicsConfiguration gc = gs.getDefaultConfiguration();

            bimage = gc.createCompatibleImage(

                image.getWidth(null), image.getHeight(null), transparency);

        } catch (HeadlessException e) {

            // The system does not have a screen

        }

    

        if (bimage == null) {

            // Create a buffered image using the default color model

            int type = BufferedImage.TYPE_INT_RGB;

            //int type = BufferedImage.TYPE_3BYTE_BGR;//by wang

            /*if (hasAlpha) {

                type = BufferedImage.TYPE_INT_ARGB;

            }*/

            bimage = new BufferedImage(image.getWidth(null), image.getHeight(null), type);

        }

    

        // Copy image to buffered image

        Graphics g = bimage.createGraphics();

    

        // Paint the image onto the buffered image

        g.drawImage(image, 0, 0, null);

        g.dispose();

    

        return bimage;

    }

以上的方法可以生成品質較高無鋸齒的新圖像文件

 

還有以下方法生成縮略圖的，如果是圖像失真較大， 圖形可以用以下方法

                  //BufferedImage src = ImageIO.read(is);

                    Image image=Toolkit.getDefaultToolkit().getImage(file.getPath());//用它可以讀取丟失ICC信息的圖片

                    BufferedImageBuilder bib=new BufferedImageBuilder();

                    BufferedImage src=BufferedImageBuilder.toBufferedImage(image);

                    //BufferedImage src=bib.bufferImage(image);

                    int w=src.getWidth();

                    int h=src.getHeight();

                    int size=getFileSize(flag);

                    if(size==0)size=h;

                    int nw=size;

                    int nh=(nw*h)/w;

                    if(nh>size){

                        nh=size;

                        nw=(nh*w)/h;

                    }

                    

                    //縮圖的比例

                    double sx=(double)nw/w;

                    double sy=(double)nh/h;

                    AffineTransform transform=new AffineTransform();

                    transform.setToScale(sx, sy);

                    AffineTransformOp ato=new AffineTransformOp(transform,null);

                    int type=src.getColorModel().getColorSpace().getType();

                    if(type==5){

                        //type=BufferedImage.TYPE_3BYTE_BGR;

                        type=BufferedImage.TYPE_INT_RGB;

                    }else if(type==6){

                        type=BufferedImage.TYPE_BYTE_GRAY;

                    }

                    BufferedImage tag=new BufferedImage(nw, nh,type);

                    ato.filter(src, tag);

                    if(isGray&&type!=6){

                        //生成灰色圖片

                        tag=getGrayImage(tag);

                    }

                    ImageIO.write(tag, "jpeg", imageFile);

                    tag.flush();

                    src.flush();

                    is.close();

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我在做生成缩略图时，发现了有些图片生成后会蒙上一层红色的图层，变色变得很难看，在网上搜索了一下，于是发现了上面那段代码，解决了那个问题，但是听说在Linux上会报错，这个我还没试过，有试过的兄弟麻烦给个回复~

本文转载自：

http://www.cnblogs.com/waya/archive/2008/11/04/1326402.html