图片缩放

/**
	 * 通过传进来的二进制图片流，将图片缩放后返回，用于文件上传取得缩放图，然后存数据库
	 * 
	 * @param bt
	 *            原图二进制
	 * @param targetW
	 *            目标宽度
	 * @param targetH
	 *            目标长度
	 * @return 缩放后图片的二进制
	 * @throws IOException
	 *             流读写异常
	 */
	public static byte[] resize(byte[] bt, Integer targetW, Integer targetH)
			throws IOException {
		ByteArrayInputStream bai = new java.io.ByteArrayInputStream(bt);
		BufferedImage bimg = javax.imageio.ImageIO.read(bai);
		BufferedImage target = resize(bimg, targetW, targetH);
		ByteArrayOutputStream os = new ByteArrayOutputStream();
		JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);
		encoder.encode(target);
		byte[] arr = os.toByteArray();
		os.flush();
		os.close();
		bai.close();
		return arr;
	}

 昨天做的一个图片缩放，能够将上传的文件进行缩放后返回字节数组，然后存放数据库或其它操作。

 

public static BufferedImage resize(BufferedImage source, int targetW,
			int targetH) throws IOException {
		// targetW，targetH分别表示目标长和宽
		int type = source.getType();
		BufferedImage target = null;
		double sx = (double) targetW / source.getWidth();
		double sy = (double) targetH / source.getHeight();
		// 这里想实现在targetW，targetH范围内实现等比缩放。如果不需要等比缩放
		// 则将下面的if else语句注释即可
		if (sx > sy) {
			sx = sy;
			targetW = (int) (sx * source.getWidth());
		} else {
			sy = sx;
			targetH = (int) (sy * source.getHeight());
		}
		if (type == BufferedImage.TYPE_CUSTOM) {
			ColorModel cm = source.getColorModel();
			WritableRaster raster = cm.createCompatibleWritableRaster(targetW,
					targetH);
			boolean alphaPremultiplied = cm.isAlphaPremultiplied();
			target = new BufferedImage(cm, raster, alphaPremultiplied, null);
		} else
			target = new BufferedImage(targetW, targetH, type);
		Graphics2D g = target.createGraphics();

		g.setRenderingHint(RenderingHints.KEY_RENDERING,
				RenderingHints.VALUE_RENDER_QUALITY);
		g.drawRenderedImage(source, AffineTransform.getScaleInstance(sx, sy));
		g.dispose();
		return target;
	}