图片压缩质量压缩，比例压缩，采样率压缩，JPEG压缩
思路：根据控件的尺寸或图片要放大显示的尺寸作为参数去压缩图片
原图为6M，以下是各种压缩的效果

image.png

以下贴出代码：

质量压缩

   /**
     * 质量压缩
     *
     * @param bitmap  要压缩的bitmap
     * @param quality 要压缩的质量系数，范围0-100，越小压缩率越高
     */
    public Bitmap getCompressBitmapByQuality(Bitmap bitmap, int quality) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, quality, bos);
        return BitmapFactory.decodeByteArray(bos.toByteArray(), 0, bos.toByteArray().length);
    }

比例压缩

    /**
     * 比例压缩
     */
    private Bitmap getCompressBitmapByScale(Bitmap bitmap, int maxW, int maxH) {
        int w = bitmap.getWidth();
        int h = bitmap.getHeight();

        float sx = (float) maxW / (float) w;
        float sy = (float) maxH / (float) h;

        Matrix matrix = new Matrix();
        matrix.setScale(sx, sy);

        return Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
    }

采样率压缩

/**
     * 采样率压缩
     */
    private Bitmap getCompressBitmapBySampleSize(Bitmap bitmap, int sampleSize) {
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inSampleSize = sampleSize;
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, bos);
        return BitmapFactory.decodeByteArray(bos.toByteArray(), 0,
                bos.toByteArray().length, options);
    }

JPEG压缩

/**
     * 使用so来压缩图片
     */
    public void compressImage(View view) {
        // Android Q中会将文件存储到该应用的沙盒文件路径下，不需要申请文件读写的权限
        File picturePath = getExternalFilesDir(Environment.DIRECTORY_PICTURES);
        String path = picturePath + File.separator + "compressImg";

        Log.i("TAG", "  路径：" + path);
        //沙盒下创建文件夹
        File file = new File(path);
        if (file.exists() || file.mkdirs()) {
            //BitmapFactory.Options options = new BitmapFactory.Options();
            //Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.tm2);
            //options.inJustDecodeBounds = false;
            //Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.tm2, options);
            Bitmap bitmap = readBitmap();
            ImageCompress compress = new ImageCompress();
            long start = System.currentTimeMillis();
            String imgPath = path + File.separator + "compressSo.jpg";
            int i = compress.compressBitmap(bitmap, 30, imgPath);
            if (i == 1) {
                long l = System.currentTimeMillis() - start;
                Log.i("TAG", "  压缩并存储成功  耗时：" + l);
            } else {
                Log.i("TAG", "  压缩并存储失败");
            }
        }
    }

package com.example.image;

import android.graphics.Bitmap;

import java.nio.ByteBuffer;

public class ImageCompress {

    static {
        System.loadLibrary("imageCompress");
    }

    /**
     * NDK方法加载图片
     *
     * @param bitmap   图片bitmap
     * @param quality  压缩的质量
     * @param fileName 压缩后的路径
     * @return
     */
    public native int compressBitmap(Bitmap bitmap, int quality,
                                            String fileName);

    public native ByteBuffer getImage(String fileName);

    public native ByteBuffer getImage2(Bitmap bitmap, int quality);

    public native void release(ByteBuffer byteBuffer);
}

项目的地址：