Android 实现4MB以上大图片压缩不失真方法

  1 import java.io.ByteArrayOutputStream;
  2 import java.io.File;
  3 
  4 import android.content.Context;
  5 import android.content.Intent;
  6 import android.graphics.Bitmap;
  7 import android.graphics.BitmapFactory;
  8 import android.net.Uri;
  9 import android.os.Environment;
 10 import android.util.Base64;
 11 
 12 public class PictureUtil {
 13 
 14     /**
 15      * 把bitmap转换成String
 16      * 
 17      * @param filePath
 18      * @return
 19      */
 20     public static String bitmapToString(String filePath) {
 21         Bitmap bm = getSmallBitmap(filePath);
 22         ByteArrayOutputStream baos = new ByteArrayOutputStream();
 23         bm.compress(Bitmap.CompressFormat.JPEG, 40, baos);
 24         byte[] b = baos.toByteArray();
 25         int x = b.length;
 26         System.out.println("" + x);
 27         return Base64.encodeToString(b, Base64.DEFAULT);
 28 
 29     }
 30 
 31     /**
 32      * 计算图片的缩放值
 33      * 
 34      * @param options
 35      * @param reqWidth
 36      * @param reqHeight
 37      * @return
 38      */
 39     public static int calculateInSampleSize(BitmapFactory.Options options,
 40             int reqWidth, int reqHeight) {
 41         // Raw height and width of image
 42         final int height = options.outHeight;
 43         final int width = options.outWidth;
 44         int inSampleSize = 1;
 45 
 46         if (height > reqHeight || width > reqWidth) {
 47 
 48             // Calculate ratios of height and width to requested height and
 49             // width
 50             final int heightRatio = Math.round((float) height
 51                     / (float) reqHeight);
 52             final int widthRatio = Math.round((float) width / (float) reqWidth);
 53 
 54             // Choose the smallest ratio as inSampleSize value, this will
 55             // guarantee
 56             // a final image with both dimensions larger than or equal to the
 57             // requested height and width.
 58             inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
 59         }
 60 
 61         return inSampleSize;
 62     }
 63 
 64     /**
 65      * 根据路径获得突破并压缩返回bitmap用于显示
 66      * 
 67      * @param imagesrc
 68      * @return
 69      */
 70     public static Bitmap getSmallBitmap(String filePath) {
 71         final BitmapFactory.Options options = new BitmapFactory.Options();
 72         options.inJustDecodeBounds = true;
 73         BitmapFactory.decodeFile(filePath, options);
 74 
 75         // Calculate inSampleSize
 76         options.inSampleSize = calculateInSampleSize(options, 480, 800);
 77 
 78         // Decode bitmap with inSampleSize set
 79         options.inJustDecodeBounds = false;
 80 
 81         return BitmapFactory.decodeFile(filePath, options);
 82     }
 83 
 84     /**
 85      * 根据路径删除图片
 86      * 
 87      * @param path
 88      */
 89     public static void deleteTempFile(String path) {
 90         File file = new File(path);
 91         if (file.exists()) {
 92             file.delete();
 93         }
 94     }
 95 
 96     /**
 97      * 添加到图库
 98      */
 99     public static void galleryAddPic(Context context, String path) {
100         Intent mediaScanIntent = new Intent(
101                 Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
102         File f = new File(path);
103         Uri contentUri = Uri.fromFile(f);
104         mediaScanIntent.setData(contentUri);
105         context.sendBroadcast(mediaScanIntent);
106     }
107 
108     /**
109      * 获取保存图片的目录
110      * 
111      * @return
112      */
113     public static File getAlbumDir() {
114         File dir = new File(
115                 Environment
116                         .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
117                 getAlbumName());
118         if (!dir.exists()) {
119             dir.mkdirs();
120         }
121         return dir;
122     }
123 
124     /**
125      * 获取保存 隐患检查的图片文件夹名称
126      * 
127      * @return
128      */
129     public static String getAlbumName() {
130         return "sheguantong";
131     }
132 }
调用：
String content = PictureUtil.bitmapToString("/storage/sdcard0/Pictures/sheguantong/test.jpg");
System.out.println("" + content);