Android 图片压缩，Bitmap旋转，bitmap与byte[]之间相互转换，Bitmap与String互转

原创已于 2022-10-15 09:44:31 修改 · 4k 阅读

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#Android 图片旋转 #图片压缩 #bitmap与byte[]之间相互转换 #oom #Bitmap与String互转

于 2019-05-07 15:00:49 首次发布

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博客围绕Android图片处理展开，介绍了图片压缩方法，可将2.22MB图片压缩至200KB，还包含bitmap与byte[]、Bitmap与String的相互转换方法，以及图片旋转方法。同时针对频繁setImageBitmap引起的oom问题，给出了在<application>里添加相关属性的解决办法。

频繁setImageBitmap引起oom问题解决方法

Glide.with(gsewmimg).load(getCodeBitmap(response.data.skip, R.mipmap.zhifuicon)).into(gsewmimg);

压缩前后。图片大小 2.22MB——>200KB

1、图片压缩方法：

Bitmap bitmap;
byte[] buff;
buff = Bitmap2Bytes(bitmap);
BitmapFactory.Options ontain = new BitmapFactory.Options();
ontain.inSampleSize = 7;//值1为原图。值越大，压缩图片越小1-20
bitmap = BitmapFactory.decodeByteArray(buff, 0, buff.length, ontain);

压缩方法2：

int height = (int) ( mybitmap.getHeight() * (512.0 / mybitmap.getWidth()) );
mybitmap = Bitmap.createScaledBitmap(mybitmap, 512, height, true);

2、bitmap转byte

private byte[] Bitmap2Bytes(Bitmap bm) {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
return baos.toByteArray();
}

3、byte转bitmap

private Bitmap Bytes2Bimap(byte[] b) {
if (b.length != 0) {
return BitmapFactory.decodeByteArray(b, 0, b.length);
} else {
return null;
}
}

方法二，bitmap 转byte

              Bitmap frame = mCamera != null ? mCamera.Snapshot(mSelectedChannel) : null;
                    frame = rotate(frame, 90);
                    byte[] snapshot = getByteArrayFromBitmap(frame);
                    if (snapshot!=null){
                        String imageString = new String(Base64.encode(snapshot,Base64.DEFAULT));
//                LgqLogPlus.e("获取到imgstring保存了===== "+imageString);
                        SharedPreUtil.putString(mDevUID,imageString);
                    }

public static byte[] getByteArrayFromBitmap(Bitmap bitmap) {

    if (bitmap != null && !bitmap.isRecycled()) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 0, bos);
        return bos.toByteArray();
    } else {
        return null;
    }
}

byte转bitmap

        String imgstring = SharedPreUtil.getString(this,mDevUID);
//       LgqLogPlus.e("获取到imgstring==== "+imgstring);
            if (imgstring!=null){
                byte[] bytsSnapshot = Base64.decode(imgstring.getBytes(), Base64.DEFAULT);
                Bitmap snapshot = (bytsSnapshot != null && bytsSnapshot.length > 0) ? getBitmapFromByteArray(bytsSnapshot) : null;
                bgimg.setImageBitmap(snapshot);
            }

public static Bitmap getBitmapFromByteArray(byte[] byts) {

    InputStream is = new ByteArrayInputStream(byts);
    return BitmapFactory.decodeStream(is, null, getBitmapOptions(2));
}

public static BitmapFactory.Options getBitmapOptions(int scale) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inPurgeable = true;
    options.inInputShareable = true;
    options.inSampleSize = scale;

    try {
        BitmapFactory.Options.class.getField("inNativeAlloc").setBoolean(options, true);
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return options;
}

旋转方法：

//Rotate Bitmap
public final static Bitmap rotate(Bitmap b, float degrees) {
    if (degrees != 0 && b != null) {
        Matrix m = new Matrix();
        m.setRotate(degrees, (float) b.getWidth() / 2,
                (float) b.getHeight() / 2);

        Bitmap b2 = Bitmap.createBitmap(b, 0, 0, b.getWidth(),
                b.getHeight(), m, true);
        if (b != b2) {
            b.recycle();
            b = b2;
        }

    }
    return b;
}

调用

bitmap = rotate(bitmap,90);

效果

选图

Android报错：Throwing OutOfMemoryError failed to allocate a 42793710 byte allocation with 52488 free by

在<application>里加上android:hardwareAccelerated="false" 和 android:largeHeap="true"成功解决

Bitmap与String互转

Bitmap frame = BitmapFactory.decodeResource(getResources(),R.mipmap.iv_charge2 );

byte[] snapshot = getByteArrayFromBitmap(frame);

if (snapshot!=null){
    String imageString = new String(Base64.encode(snapshot,Base64.DEFAULT));

    if (imageString!=null){
        byte[] bytsSnapshot = Base64.decode(imageString.getBytes(), Base64.DEFAULT);
        Bitmap snapshot2 = (bytsSnapshot != null && bytsSnapshot.length > 0) ? getBitmapFromByteArray(bytsSnapshot) : null;
        imageView.setImageBitmap(snapshot2);
    }
}

工具：

public static byte[] getByteArrayFromBitmap(Bitmap bitmap) {

    if (bitmap != null && !bitmap.isRecycled()) {
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.PNG, 0, bos);
        return bos.toByteArray();
    } else {
        return null;
    }
}

public static Bitmap getBitmapFromByteArray(byte[] byts) {

    InputStream is = new ByteArrayInputStream(byts);
    return BitmapFactory.decodeStream(is, null, getBitmapOptions(2));
}

public static BitmapFactory.Options getBitmapOptions(int scale) {
    BitmapFactory.Options options = new BitmapFactory.Options();
    options.inPurgeable = true;
    options.inInputShareable = true;
    options.inSampleSize = scale;

    try {
        BitmapFactory.Options.class.getField("inNativeAlloc").setBoolean(options, true);
    } catch (IllegalArgumentException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (SecurityException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IllegalAccessException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (NoSuchFieldException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return options;
}

private static void readBitmapScale(Context context, Uri uri, BitmapFactory.Options options) {
    if (uri == null) {
        return;
    }
    String scheme = uri.getScheme();
    if (ContentResolver.SCHEME_CONTENT.equals(scheme) ||
            ContentResolver.SCHEME_FILE.equals(scheme)) {
        InputStream stream = null;
        try {
            stream = context.getContentResolver().openInputStream(uri);
            BitmapFactory.decodeStream(stream, null, options);
        } catch (Exception e) {
            Log.w("readBitmapScale", "Unable to open content: " + uri, e);
        } finally {
            if (stream != null) {
                try {
                    stream.close();
                } catch (IOException e) {
                    Log.e("readBitmapScale", "Unable to close content: " + uri, e);
                }
            }
        }
    } else if (ContentResolver.SCHEME_ANDROID_RESOURCE.equals(scheme)) {
        Log.e("readBitmapScale", "Unable to close content: " + uri);
    } else {
        Log.e("readBitmapScale", "Unable to close content: " + uri);
    }
}

private static Bitmap readBitmapData(Context context, Uri uri, BitmapFactory.Options options) {
    if (uri == null) {
        return null;
    }
    Bitmap bitmap = null;
    String scheme = uri.getScheme();
    if (ContentResolver.SCHEME_CONTENT.equals(scheme) ||
            ContentResolver.SCHEME_FILE.equals(scheme)) {
        InputStream stream = null;
        try {
            stream = context.getContentResolver().openInputStream(uri);
            bitmap = BitmapFactory.decodeStream(stream, null, options);
        } catch (Exception e) {
            Log.e("readBitmapData", "Unable to open content: " + uri, e);
        } finally {
            if (stream != null) {
                try {
                    stream.close();
                } catch (IOException e) {
                    Log.e("readBitmapData", "Unable to close content: " + uri, e);
                }
            }
        }
    } else if (ContentResolver.SCHEME_ANDROID_RESOURCE.equals(scheme)) {
        Log.e("readBitmapData", "Unable to close content: " + uri);
    } else {
        Log.e("readBitmapData", "Unable to close content: " + uri);
    }
    return bitmap;
}