比例压缩,,质量压缩

 package com.example.ggq.scalecompressbitmapstudy;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ImageView;
import java.io.BufferedOutputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;

public class Main2Activity extends AppCompatActivity {

    private ImageView iv_image;
    private static final String TAG = "Main2Activity";
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        iv_image = findViewById(R.id.iv_image);
        getimage("/storage/emulated/0/Pictures/Screenshots/picture.jpg");
    }
    private Bitmap getimage(String srcPath) {
        BitmapFactory.Options newOpts = new BitmapFactory.Options();
        //开始读入图片，此时把options.inJustDecodeBounds 设回true了
        newOpts.inJustDecodeBounds = true;
        Bitmap bitmap = BitmapFactory.decodeFile(srcPath,newOpts);//此时返回bm为空

        newOpts.inJustDecodeBounds = false;
        int w = newOpts.outWidth;
        int h = newOpts.outHeight;
        //现在主流手机比较多是800*480分辨率，所以高和宽我们设置为
        float hh = 800f;//这里设置高度为800f
        float ww = 480f;//这里设置宽度为480f
        //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 be = 1;//be=1表示不缩放
        if (w > h && w > ww) {//如果宽度大的话根据宽度固定大小缩放
            be = (int) (newOpts.outWidth / ww);
        } else if (w < h && h > hh) {//如果高度高的话根据宽度固定大小缩放
            be = (int) (newOpts.outHeight / hh);
        }
        if (be <= 0)
            be = 1;
        newOpts.inSampleSize = be;//设置缩放比例
        //重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了
        bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
        return compressImage(bitmap);//压缩好比例大小后再进行质量压缩
    }
    private Bitmap compressImage(Bitmap image) {
        Log.d(TAG, "compressImage: "+"ddao l ");
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        image.compress(Bitmap.CompressFormat.JPEG, 100, baos);//质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中
        int options = 100;
        while ( baos.toByteArray().length / 1024>100) {    //循环判断如果压缩后图片是否大于100kb,大于继续压缩
            baos.reset();//重置baos即清空baos
            options -= 10;//每次都减少10
            image.compress(Bitmap.CompressFormat.JPEG, options, baos);//这里压缩options%，把压缩后的数据存放到baos中

        }
        ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//把压缩后的数据baos存放到ByteArrayInputStream中
        Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//把ByteArrayInputStream数据生成图片
        iv_image.setImageBitmap(bitmap);
        return bitmap;
    }
}