Android 图片压缩实现过程代码

Android图片压缩非两种，一种质量压缩，一种像素压缩，前者多用于图片上传时，后者多用于本地图片展示缩略图时。总结并记录一下，方便以后使用。
具体的分析可以参考这篇文章，http://www.codeceo.com/article/android-image-compression.html
/** * Image compress factory class */public class ImageUtils {    /**     * Get bitmap from specified image path     *     * @param imgPath image path     * @return Bitmap     */    public Bitmap getBitmap(String imgPath) {        // Get bitmap through image path        BitmapFactory.Options newOpts = new BitmapFactory.Options();        newOpts.inJustDecodeBounds = false;        // Do not compress        newOpts.inSampleSize = 1;        newOpts.inPreferredConfig = Config.RGB_565;        return BitmapFactory.decodeFile(imgPath, newOpts);    }    /**     * Store bitmap into specified image path     *     * @param bitmap     * @param outPath     * @throws FileNotFoundException     */    public static void storeImage(Bitmap bitmap, String outPath) throws FileNotFoundException {        FileOutputStream os = new FileOutputStream(outPath);        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, os);    }    /**     * Compress image by pixel, this will modify image width/height.     * Used to get thumbnail     *     * @param imgPath image path     * @param pixelW  target pixel of width     * @param pixelH  target pixel of height     * @return     */    public Bitmap ratio(String imgPath, float pixelW, float pixelH) {        BitmapFactory.Options newOpts = new BitmapFactory.Options();        // 开始读入图片，此时把options.inJustDecodeBounds 设回true，即只读边不读内容        newOpts.inJustDecodeBounds = true;        newOpts.inPreferredConfig = Config.RGB_565;        // Get bitmap info, but notice that bitmap is null now        BitmapFactory.decodeFile(imgPath, newOpts);        int originalWidth = newOpts.outWidth;        int originalHeight = newOpts.outHeight;        // 想要缩放的目标尺寸        float convertedWidth = pixelW;// 设置宽度为120f，可以明显看到图片缩小了        float convertedHeight = pixelH;// 设置高度为240f时，可以明显看到图片缩小了        // 缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可        int ratio = 1;     //ratio=1表示不缩放        if (originalWidth > originalHeight && originalWidth > convertedWidth) { //如果宽度大的话根据宽度固定大小缩放            ratio = (int) (newOpts.outWidth / convertedWidth);        } else if (originalWidth < originalHeight && originalHeight > convertedHeight) { //如果高度高的话根据高度固定大小缩放            ratio = (int) (newOpts.outHeight / convertedHeight);        }        if (ratio <= 0) {            ratio = 1;        }        newOpts.inJustDecodeBounds = false;        newOpts.inSampleSize = ratio;//设置缩放比例        // 开始压缩图片，注意此时已经把options.inJustDecodeBounds 设回false了        Bitmap bitmap = BitmapFactory.decodeFile(imgPath, newOpts);        // 压缩好比例大小后再进行质量压缩        //        return compress(bitmap, maxSize); // 这里再进行质量压缩的意义不大，反而耗资源，删除        return bitmap;    }    /**     * Compress image by size, this will modify image width/height.     * Used to get thumbnail     *     * @param image     * @param pixelW target pixel of width     * @param pixelH target pixel of height     * @return     */    public Bitmap ratio(Bitmap image, float pixelW, float pixelH) {        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();        image.compress(Bitmap.CompressFormat.JPEG, 100, byteArrayOutputStream);        if (byteArrayOutputStream.toByteArray().length / 1024 > 1024) {//判断如果图片大于1M,进行压缩避免在生成图片（BitmapFactory            // .decodeStream）时溢出            byteArrayOutputStream.reset();//重置baos即清空baos            image.compress(Bitmap.CompressFormat.JPEG, 50, byteArrayOutputStream);//这里压缩50%，把压缩后的数据存放到baos中        }        ByteArrayInputStream byteArrayInputStream;        // 开始压缩图片，注意此时已经把options.inJustDecodeBounds 设回false了        byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());        BitmapFactory.Options newOpts = new BitmapFactory.Options();        // 开始读入图片，此时把options.inJustDecodeBounds 设回true，即只读边不读内容        newOpts.inJustDecodeBounds = true;        newOpts.inPreferredConfig = Config.RGB_565;        BitmapFactory.decodeStream(byteArrayInputStream, null, newOpts);        int originalWidth = image.getWidth();        int originalHeight = image.getHeight();        // 想要缩放的目标尺寸        float convertedWidth = pixelW;// 设置宽度为120f，可以明显看到图片缩小了        float convertedHeight = pixelH;// 设置高度为240f时，可以明显看到图片缩小了        // 缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可        int ratio = 1;     //ratio=1表示不缩放        if (originalWidth > originalHeight && originalWidth > convertedWidth) { //如果宽度大的话根据宽度固定大小缩放            ratio = (int) (newOpts.outWidth / convertedWidth);        } else if (originalWidth < originalHeight && originalHeight > convertedHeight) { //如果高度高的话根据高度固定大小缩放            ratio = (int) (newOpts.outHeight / convertedHeight);        }        if (ratio <= 0) {            ratio = 1;        }        newOpts.inJustDecodeBounds = false; //注意此时已经把options.inJustDecodeBounds 设回false了        newOpts.inSampleSize = ratio; //设置缩放比例        return BitmapFactory.decodeStream(byteArrayInputStream, null, newOpts);    }    /**     * Compress by quality,  and generate image to the path specified     * Use to upload     *     * @param image     * @param outPath     * @param maxSize target will be compressed to be smaller than this size.(kb)     * @throws IOException     */    public static void compressAndGenImage(Bitmap image, String outPath, int maxSize) throws            IOException {        ByteArrayOutputStream os = new ByteArrayOutputStream();        // scale        int options = 100;        // Store the bitmap into output stream(no compress)        image.compress(Bitmap.CompressFormat.JPEG, options, os);        // Compress by loop        while (os.toByteArray().length / 1024 > maxSize) {            // Clean up os            os.reset();            // interval 10            options -= 10;            if (options < 0) {                options = 0;                image.compress(Bitmap.CompressFormat.JPEG, options, os);                break;            }            image.compress(Bitmap.CompressFormat.JPEG, options, os);        }        // Generate compressed image file        FileOutputStream fos = new FileOutputStream(outPath);        fos.write(os.toByteArray());        fos.flush();        fos.close();    }    /**     * Compress by quality,  and generate image to the path specified     *     * @param imgPath     * @param outPath     * @param maxSize     target will be compressed to be smaller than this size.(kb)     * @param needsDelete Whether delete original file after compress     * @throws IOException     */    public void compressAndGenImage(String imgPath, String outPath, int maxSize, boolean            needsDelete) throws IOException {        compressAndGenImage(getBitmap(imgPath), outPath, maxSize);        // Delete original file        if (needsDelete) {            File file = new File(imgPath);            if (file.exists()) {                file.delete();            }        }    }    /**     * Ratio and generate thumb to the path specified     *     * @param image     * @param outPath     * @param pixelW  target pixel of width     * @param pixelH  target pixel of height     * @throws FileNotFoundException     */    public void ratioAndGenThumb(Bitmap image, String outPath, float pixelW, float pixelH) throws            FileNotFoundException {        Bitmap bitmap = ratio(image, pixelW, pixelH);        storeImage(bitmap, outPath);    }    /**     * Ratio and generate thumb to the path specified     *     * @param imgPath     * @param outPath     * @param pixelW      target pixel of width     * @param pixelH      target pixel of height     * @param needsDelete Whether delete original file after compress     * @throws FileNotFoundException     */    public void ratioAndGenThumb(String imgPath, String outPath, float pixelW, float pixelH,                                 boolean needsDelete) throws FileNotFoundException {        Bitmap bitmap = ratio(imgPath, pixelW, pixelH);        storeImage(bitmap, outPath);        // Delete original file        if (needsDelete) {            File file = new File(imgPath);            if (file.exists()) {                file.delete();            }        }    }    /**     * 根据路径获取图片资源（已缩放）     *     * @param url    图片存储路径     * @param width  缩放的宽度     * @param height 缩放的高度     * @return     */    public static Bitmap getBitmapFromUrl(String url, double width, double height) {        BitmapFactory.Options options = new BitmapFactory.Options();        options.inJustDecodeBounds = true; // 设置了此属性一定要记得将值设置为false        Bitmap bitmap = BitmapFactory.decodeFile(url);        // 防止OOM发生        options.inJustDecodeBounds = false;        int mWidth = bitmap.getWidth();        int mHeight = bitmap.getHeight();        Matrix matrix = new Matrix();        float scaleWidth = 1;        float scaleHeight = 1;        // 按照固定宽高进行缩放        // 这里希望知道照片是横屏拍摄还是竖屏拍摄        // 因为两种方式宽高不同，缩放效果就会不同        // 这里用了比较笨的方式        if (mWidth <= mHeight) {            scaleWidth = (float) (width / mWidth);            scaleHeight = (float) (height / mHeight);        } else {            scaleWidth = (float) (height / mWidth);            scaleHeight = (float) (width / mHeight);        }        // 按照固定大小对图片进行缩放        matrix.postScale(scaleWidth, scaleHeight);        Bitmap newBitmap = Bitmap.createBitmap(bitmap, 0, 0, mWidth, mHeight, matrix, true);        // 用完了记得回收        bitmap.recycle();        try {            storeImage(newBitmap, url);        } catch (FileNotFoundException e) {            e.printStackTrace();        }        return newBitmap;    }}
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