图片工具类

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这是项目中用到的图片工具类，记录于此。

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.media.ExifInterface;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

public class BitmapUtils {
    public static Bitmap getSmallBitmap(String filePath) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        //inJustDecodeBounds设置为true，可以不把图片读到内存中,但依然可以计算出图片的大小
        BitmapFactory.decodeFile(filePath, options);

        // Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, 480, 800);

        // Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        //此时返回的就是已经被压缩的bitmap。。可以用于显示在界面上
        return BitmapFactory.decodeFile(filePath, options);
    }

    /**
     * 计算图片的缩放值
     */
    public static int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int heightRatio = Math.round((float) height / (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }
        return inSampleSize;
    }

    /**
     * 压缩图片到指定位置(默认JPG格式)
     *
     * @param filePath   需要压缩的图片路径
     * @param targetPath 压缩后的图片路径
     * @param quality    图片质量，0~100
     * @return 压缩后的图片路径
     */
    public static String compressImage(String filePath, String targetPath, int quality) {
        Bitmap bm = getSmallBitmap(filePath);//获取一定尺寸的图片
        int degree = readPictureDegree(filePath);//获取相片拍摄角度
        if (degree != 0) {//旋转照片角度，防止头像横着显示
            bm = rotateBitmap(bm, degree);
        }
        File outputFile = new File(targetPath);
        try {
            if (!outputFile.exists()) {
                outputFile.getParentFile().mkdirs();
                //outputFile.createNewFile();
            } else {
                outputFile.delete();
            }
            FileOutputStream out = new FileOutputStream(outputFile);
            bm.compress(Bitmap.CompressFormat.JPEG, quality, out);
        } catch (Exception e) {
        }
        return outputFile.getPath();
    }

    /**
     * 获取照片角度
     *
     * @param path
     * @return
     */
    public static int readPictureDegree(String path) {
        int degree = 0;
        try {
            ExifInterface exifInterface = new ExifInterface(path);
            int orientation = exifInterface.getAttributeInt(
                    ExifInterface.TAG_ORIENTATION,
                    ExifInterface.ORIENTATION_NORMAL);
            switch (orientation) {
                case ExifInterface.ORIENTATION_ROTATE_90:
                    degree = 90;
                    break;
                case ExifInterface.ORIENTATION_ROTATE_180:
                    degree = 180;
                    break;
                case ExifInterface.ORIENTATION_ROTATE_270:
                    degree = 270;
                    break;
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        return degree;
    }

    /**
     * 旋转照片
     *
     * @param bitmap
     * @param degress
     * @return
     */
    public static Bitmap rotateBitmap(Bitmap bitmap, int degress) {
        if (bitmap != null) {
            Matrix m = new Matrix();
            m.postRotate(degress);
            bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(),
                    bitmap.getHeight(), m, true);
            return bitmap;
        }
        return bitmap;
    }

}