Android 玩转图片(读取图片转化Bitmap,保存本地,采样压缩)

1、权限

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

2、将图片转化为Bitmap
第一种:返回项目Resources中图片 Bitmap

//    返回项目中图片 bitmap
    private Bitmap imgToBitmap(){
        Bitmap  bitmap = BitmapFactory.decodeResource(this.getApplication().getResources(), R.mipmap.imgbitmapio);
        return bitmap;
    }

第二种:从本地获取图片(SAVE_REAL_PATH+”testImage/chen.jpeg”这是本地图片路径)

    private Bitmap imgToBitmap(){
        FileInputStream fis = null;
        try {
            fis = new FileInputStream(SAVE_REAL_PATH+"testImage/chen.jpeg");
        } catch (FileNotFoundException e) {

        }
        Bitmap bitmap  = BitmapFactory.decodeStream(fis);
        return bitmap;
    }

3、将Bitmap 转 为 byte数组

 public static byte[] BitmapBytes(Bitmap bm){
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
        return baos.toByteArray();
    }

4、采样压缩图片 压缩比例值越大 压缩度越高 (size=4 时内存能节约十倍,清晰度差不多)

public Bitmap getScaleBitmap(byte[] data,int size)
    {
        //1, 得到用来设置图片的属性参数对象
        BitmapFactory.Options options = new BitmapFactory.Options();

        //2, 解码边缘
        options.inJustDecodeBounds = true;

        //3, 进行图片解码
        BitmapFactory.decodeByteArray(data, 0, data.length, options);


        //4, 设置缩放的比例, 只能设置大于1的, 数值越多, 缩放的比例就越小
        //压缩成2的多少次幂   2 -- > 2,3 ; 大于4 小于8 都按4来压缩
        options.inSampleSize = size;

        //5, 将图片的质量设置为RGB_565
        options.inPreferredConfig = Bitmap.Config.RGB_565;

        //6,锁住图片边缘
        options.inJustDecodeBounds = false;

        //7, 通过参数对象, 获取新的图片
        Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, options);

        return bitmap;

    }

5、保存图片到本地

//成员变量
private static final String SAVE_PIC_PATH=Environment.getExternalStorageState().equalsIgnoreCase(Environment.MEDIA_MOUNTED)
            ? Environment.getExternalStorageDirectory().getAbsolutePath() : "/mnt/sdcard/chenxh/mytestApp";//判断sd卡
    private static final String SAVE_REAL_PATH = SAVE_PIC_PATH+  "/res/chenchen";//保存位置


 //保存图片到本地路径
    public static void saveImage(Bitmap bm, String fileName, String path) throws IOException {
        String subForder = SAVE_REAL_PATH + path;
        File foder = new File(subForder);
        if (!foder.exists()) {
            foder.mkdirs();
        }
        File myCaptureFile = new File(subForder, fileName);
        if (!myCaptureFile.exists()) {
            myCaptureFile.createNewFile();
        }
        BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));
        bm.compress(Bitmap.CompressFormat.JPEG, 80, bos);
        bos.flush();
        bos.close();
    }

6、执行

try {
                    createFolder();
                    Bitmap bitmap1 = imgToBitmap();
                    saveImage(getScaleBitmap( BitmapBytes(bitmap1),4),"chen123.jpeg","/testImage");
                } catch (IOException e) {

                }

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