简单实用的android 图片的压缩

上传图片的时候我们经常因为图片太大问题要进行压缩图片的；本例子通过拍照得到一张图片来进行压缩展示的

直接贴代码了（因为都比较简单，注释的话很清楚，主要的操作还是在最后一步）：

首先看下工具类

<span style="font-size:14px;">package com.example.compressphoto;import java.io.ByteArrayOutputStream;import java.io.File;import android.content.Context;import android.content.Intent;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.net.Uri;import android.os.Environment;import android.util.Base64;public class PictureUtil {/** * 把bitmap转换成String *  * @param filePath * @return */public static String bitmapToString(String filePath) {Bitmap bm = getSmallBitmap(filePath);ByteArrayOutputStream baos = new ByteArrayOutputStream();bm.compress(Bitmap.CompressFormat.JPEG, 40, baos);byte[] b = baos.toByteArray();return Base64.encodeToString(b, Base64.DEFAULT);}/** * 计算图片的缩放值 *  * @param options * @param reqWidth * @param reqHeight * @return */public static int calculateInSampleSize(BitmapFactory.Options options,int reqWidth, int reqHeight) {// Raw height and width of imagefinal int height = options.outHeight;final int width = options.outWidth;int inSampleSize = 1;if (height > reqHeight || width > reqWidth) {// Calculate ratios of height and width to requested height and// widthfinal int heightRatio = Math.round((float) height/ (float) reqHeight);final int widthRatio = Math.round((float) width / (float) reqWidth);// Choose the smallest ratio as inSampleSize value, this will// guarantee// a final image with both dimensions larger than or equal to the// requested height and width.inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;}return inSampleSize;}/** * 根据路径获得突破并压缩返回bitmap用于显示 *  * @param imagesrc * @return */public static Bitmap getSmallBitmap(String filePath) {final BitmapFactory.Options options = new BitmapFactory.Options();options.inJustDecodeBounds = true;BitmapFactory.decodeFile(filePath, options);// Calculate inSampleSizeoptions.inSampleSize = calculateInSampleSize(options, 480, 800);// Decode bitmap with inSampleSize setoptions.inJustDecodeBounds = false;return BitmapFactory.decodeFile(filePath, options);}/** * 根据路径删除图片 *  * @param path */public static void deleteTempFile(String path) {File file = new File(path);if (file.exists()) {file.delete();}}/** * 添加到图库 */public static void galleryAddPic(Context context, String path) {Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);File f = new File(path);Uri contentUri = Uri.fromFile(f);mediaScanIntent.setData(contentUri);context.sendBroadcast(mediaScanIntent);}/** * 获取保存图片的目录 *  * @return */public static File getAlbumDir() {File dir = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),getAlbumName());if (!dir.exists()) {dir.mkdirs();}return dir;}/** * 获取 保存图片文件夹名称 *  * @return */public static String getAlbumName() {return "picture";}}</span>

首先是调用拍照

<span style="font-size:14px;">/** * 拍照*/public void takephono(View view){Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);try {// 指定存放拍摄照片的位置File f = createImageFile();takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f));startActivityForResult(takePictureIntent, REQUEST_TAKE_PHOTO);} catch (IOException e) {e.printStackTrace();}}</span>

<span style="font-size:14px;">/** * 把程序拍摄的照片放到 SD卡的 Pictures目录中 picture 文件夹中 * 照片的命名规则为：wzy_20160428_173729.jpg *  * @return * @throws IOException */@SuppressLint("SimpleDateFormat")private File createImageFile() throws IOException {SimpleDateFormat format = new SimpleDateFormat("yyyyMMdd_HHmmss"); String timeStamp = format.format(new Date());String imageFileName = "wzy_" + timeStamp + ".jpg";File image = new File(PictureUtil.getAlbumDir(), imageFileName);mCurrentPhotoPath = image.getAbsolutePath();return image;}</span>

再是对拍照返回的操作

<span style="font-size:14px;">@Overrideprotected void onActivityResult(int requestCode, int resultCode, Intent data) {if (requestCode == REQUEST_TAKE_PHOTO) {if (resultCode == Activity.RESULT_OK) {// 添加到图库,这样可以在手机的图库程序中看到程序拍摄的照片PictureUtil.galleryAddPic(this, mCurrentPhotoPath);againImage.setImageBitmap(BitmapFactory.decodeFile(mCurrentPhotoPath));//不知道为啥就是显示不出来} else {// 取消照相后，删除已经创建的临时文件。PictureUtil.deleteTempFile(mCurrentPhotoPath);mCurrentPhotoPath =null;}}}</span>

然后就是我们关注的压缩的操作（给压缩之后的图片创建一个新的文件，所以我们上传服务器的文件路径就得用这个了）

<span style="font-size:14px;">/** * 压缩 * (多文件压缩使用循环的方法就,可以了) * */public void compressPhoto(View view){if (mCurrentPhotoPath != null) {try {File f = new File(mCurrentPhotoPath);Bitmap bm = PictureUtil.getSmallBitmap(mCurrentPhotoPath);//新的压缩之后的图片的路径是“原路径，只不过在名字之前加了一个small_”FileOutputStream fos = new FileOutputStream(new File(PictureUtil.getAlbumDir(), "small_" + f.getName()));bm.compress(Bitmap.CompressFormat.JPEG, 40, fos);//这里压缩40%，把压缩后的数据存放到fos中  nowImage.setImageBitmap(PictureUtil.getSmallBitmap(PictureUtil.getAlbumDir()+"/"+"small_" + f.getName()));Log.i("原始文件的大小", f.length()+"");Log.i("压缩后文件的大小",new File(PictureUtil.getAlbumDir(), "small_" + f.getName()).length()+"");} catch (Exception e) {e.printStackTrace();}} else {Toast.makeText(this, "请先点击拍照按钮拍摄照片", Toast.LENGTH_SHORT).show();}}</span>

最后demo下载链接http://www.oschina.net/code/snippet_2702417_55777

看到的一个图片压缩 框架 luban（鲁班）：https://github.com/bai53229/Luban