private void compressImageFile() {
        JFileChooser fileChooser = new JFileChooser("d://");
        fileChooser.showOpenDialog(this);
        File file = fileChooser.getSelectedFile();

        if (null != file && file.exists()) {
            Toolkit toolkit = Toolkit.getDefaultToolkit();
            Image srcImage = toolkit.getImage(file.getAbsolutePath()); // 構造Image對象
            int wideth = -1;
            int height = -1;
            boolean flag = true;
            while (flag) {
                wideth = srcImage.getWidth(null); // 得到源圖寬
                height = srcImage.getHeight(null); // 得到源圖長
                System.out.println("wideth:" + wideth + " height:" + height);
                if (wideth > 0 && height > 0) { // 因為 Toolkit.getImage 是異步讀取，如果
                                                // wideth 和 height
                                                // 都大于0，表明圖片已經加載完畢
                // imageCanvas.setImage(srcImage);
                    flag = false;
                } else {
                    try {
                        Thread.sleep(10);
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
            }

            // 加載完畢，輸出
            int w = 1024;
            float s = (float) wideth / 1024.0f;
            int h = (int) ((float) height / s);
            BufferedImage bufferedImage = new BufferedImage(w, h,
                    BufferedImage.TYPE_INT_RGB);
            // bufferedImage.getGraphics().drawImage(srcImage, 0, 0, 1024,
            // 768, null); // 繪制縮小后的圖
            boolean flag2 = false;
            while (!(flag2 = bufferedImage.getGraphics().drawImage(srcImage, 0,
                    0, w, h, this))) {
                try {
                    Thread.sleep(10);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

            try {

                File outputFile = new File("d://hhh.jpg");
                if (!outputFile.exists()) {
                    outputFile.createNewFile();
                }
                FileOutputStream out = new FileOutputStream(outputFile); // 輸出到文件流
                JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
                encoder.encode(bufferedImage); // 近JPEG編碼
                out.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }