java中的圖片按比例縮放功能

java中的圖片按比例縮放功能

1. 按固定長寬進行縮放

    /*


 * 圖片縮放,w，h為縮放的目標寬度和高度
 * src為源文件目錄，dest為縮放后保存目錄
 */
public static void zoomImage(String src,String dest,int w,int h) throws Exception {

    double wr=0,hr=0;
    File srcFile = new File(src);
    File destFile = new File(dest);

    BufferedImage bufImg = ImageIO.read(srcFile); //讀取圖片
    Image Itemp = bufImg.getScaledInstance(w, h, bufImg.SCALE_SMOOTH);//設置縮放目標圖片模板

    wr=w*1.0/bufImg.getWidth();     //獲取縮放比例
    hr=h*1.0 / bufImg.getHeight();

    AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(wr, hr), null);
    Itemp = ato.filter(bufImg, null);
    try {
        ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile); //寫入縮減后的圖片
    } catch (Exception ex) {
        ex.printStackTrace();
    }
}</pre> <h4>2. 按固定文件大小進行縮放</h4>



  /*


圖片按比率縮放
size為文件大小
*/
public static void zoomImage(String src,String dest,Integer size) throws Exception {
 File srcFile = new File(src);
 File destFile = new File(dest);
long fileSize = srcFile.length();
 if(fileSize < size * 1024)   //文件大于size k時，才進行縮放

 return;


Double rate = (size  1024  0.5) / fileSize; // 獲取長寬縮放比例
BufferedImage bufImg = ImageIO.read(srcFile);
 Image Itemp = bufImg.getScaledInstance(bufImg.getWidth(), bufImg.getHeight(), bufImg.SCALE_SMOOTH);
AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(rate, rate), null);
 Itemp = ato.filter(bufImg, null);
 try {

 ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile);

} catch (Exception ex) {

 ex.printStackTrace();

}</pre> 
來自： http://segmentfault.com/a/1190000004253565