Android图片压缩（质量压缩和尺寸压缩）&Bitmap转成字符串上传

在网上调查了图片压缩的方法并实装后，大致上可以认为有两类压缩：质量压缩（不改变图片的尺寸）和尺寸压缩（相当于是像素上的压缩）；质量压缩一般可用于上传大图前的处理，这样就可以节省一定的流量，毕竟现在的手机拍照都能达到3M左右了，尺寸压缩一般可用于生成缩略图。
两种方法都实装在了我的项目中，结果却发现在质量压缩的模块中，本来1.9M的图片压缩后反而变成3M多了，很是奇怪，再做了进一步调查终于知道原因了。下面这个博客说的比较清晰：

android图片压缩总结

总结来看，图片有三种存在形式：硬盘上时是file，网络传输时是stream，内存中是stream或bitmap，所谓的质量压缩，它其实只能实现对file的影响，你可以把一个file转成bitmap再转成file，或者直接将一个bitmap转成file时，这个最终的file是被压缩过的，但是中间的bitmap并没有被压缩，因为bigmap在内存中的大小是按像素计算的，也就是width * height，对于质量压缩，并不会改变图片的像素，所以就算质量被压缩了，但是bitmap在内存的占有率还是没变小，但你做成file时，它确实变小了；

而尺寸压缩由于是减小了图片的像素，所以它直接对bitmap产生了影响，当然最终的file也是相对的变小了；

最后把自己总结的工具类贴出来：

import java.io.ByteArrayInputStream;  
import java.io.ByteArrayOutputStream;  
import java.io.File;  
import java.io.FileNotFoundException;  
import java.io.FileOutputStream;  
import java.io.IOException;  

import android.graphics.Bitmap;  
import android.graphics.Bitmap.Config;  
import android.graphics.BitmapFactory;  

/** 
 * Image compress factory class 
 *  
 * @author  
 * 
 */  
public class ImageFactory {  

    /** 
     * Get bitmap from specified image path 
     *  
     * @param imgPath 
     * @return 
     */  
    public Bitmap getBitmap(String imgPath) {  
        // Get bitmap through image path  
        BitmapFactory.Options newOpts = new BitmapFactory.Options();  
        newOpts.inJustDecodeBounds = false;  
        newOpts.inPurgeable = true;  
        newOpts.inInputShareable = true;  
        // Do not compress  
        newOpts.inSampleSize = 1;  
        newOpts.inPreferredConfig = Config.RGB_565;  
        return BitmapFactory.decodeFile(imgPath, newOpts);  
    }  

    /** 
     * Store bitmap into specified image path 
     *  
     * @param bitmap 
     * @param outPath 
     * @throws FileNotFoundException  
     */  
    public void storeImage(Bitmap bitmap, String outPath) throws FileNotFoundException {  
        FileOutputStream os = new FileOutputStream(outPath);  
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, os);  
    }  

    /** 
     * Compress image by pixel, this will modify image width/height.  
     * Used to get thumbnail 
     *  
     * @param imgPath image path 
     * @param pixelW target pixel of width 
     * @param pixelH target pixel of height 
     * @return 
     */  
    public Bitmap ratio(String imgPath, float pixelW, float pixelH) {  
        BitmapFactory.Options newOpts = new BitmapFactory.Options();    
        // 开始读入图片，此时把options.inJustDecodeBounds 设回true，即只读边不读内容  
        newOpts.inJustDecodeBounds = true;  
        newOpts.inPreferredConfig = Config.RGB_565;  
        // Get bitmap info, but notice that bitmap is null now    
        Bitmap bitmap = BitmapFactory.decodeFile(imgPath,newOpts);  

        newOpts.inJustDecodeBounds = false;    
        int w = newOpts.outWidth;    
        int h = newOpts.outHeight;    
        // 想要缩放的目标尺寸  
        float hh = pixelH;// 设置高度为240f时，可以明显看到图片缩小了  
        float ww = pixelW;// 设置宽度为120f，可以明显看到图片缩小了  
        // 缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可    
        int be = 1;//be=1表示不缩放    
        if (w > h && w > ww) {//如果宽度大的话根据宽度固定大小缩放    
            be = (int) (newOpts.outWidth / ww);    
        } else if (w < h && h > hh) {//如果高度高的话根据宽度固定大小缩放    
            be = (int) (newOpts.outHeight / hh);    
        }    
        if (be <= 0) be = 1;    
        newOpts.inSampleSize = be;//设置缩放比例  
        // 开始压缩图片，注意此时已经把options.inJustDecodeBounds 设回false了  
        bitmap = BitmapFactory.decodeFile(imgPath, newOpts);  
        // 压缩好比例大小后再进行质量压缩  
//        return compress(bitmap, maxSize); // 这里再进行质量压缩的意义不大，反而耗资源，删除  
        return bitmap;  
    }  

    /** 
     * Compress image by size, this will modify image width/height.  
     * Used to get thumbnail 
     *  
     * @param image 
     * @param pixelW target pixel of width 
     * @param pixelH target pixel of height 
     * @return 
     */  
    public Bitmap ratio(Bitmap image, float pixelW, float pixelH) {  
        ByteArrayOutputStream os = new ByteArrayOutputStream();  
        image.compress(Bitmap.CompressFormat.JPEG, 100, os);  
        if( os.toByteArray().length / 1024>1024) {//判断如果图片大于1M,进行压缩避免在生成图片（BitmapFactory.decodeStream）时溢出      
            os.reset();//重置baos即清空baos    
            image.compress(Bitmap.CompressFormat.JPEG, 50, os);//这里压缩50%，把压缩后的数据存放到baos中    
        }    
        ByteArrayInputStream is = new ByteArrayInputStream(os.toByteArray());    
        BitmapFactory.Options newOpts = new BitmapFactory.Options();    
        //开始读入图片，此时把options.inJustDecodeBounds 设回true了    
        newOpts.inJustDecodeBounds = true;  
        newOpts.inPreferredConfig = Config.RGB_565;  
        Bitmap bitmap = BitmapFactory.decodeStream(is, null, newOpts);    
        newOpts.inJustDecodeBounds = false;    
        int w = newOpts.outWidth;    
        int h = newOpts.outHeight;    
        float hh = pixelH;// 设置高度为240f时，可以明显看到图片缩小了  
        float ww = pixelW;// 设置宽度为120f，可以明显看到图片缩小了  
        //缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可    
        int be = 1;//be=1表示不缩放    
        if (w > h && w > ww) {//如果宽度大的话根据宽度固定大小缩放    
            be = (int) (newOpts.outWidth / ww);    
        } else if (w < h && h > hh) {//如果高度高的话根据宽度固定大小缩放    
            be = (int) (newOpts.outHeight / hh);    
        }    
        if (be <= 0) be = 1;    
        newOpts.inSampleSize = be;//设置缩放比例    
        //重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了    
        is = new ByteArrayInputStream(os.toByteArray());    
        bitmap = BitmapFactory.decodeStream(is, null, newOpts);  
        //压缩好比例大小后再进行质量压缩  
//      return compress(bitmap, maxSize); // 这里再进行质量压缩的意义不大，反而耗资源，删除  
        return bitmap;  
    }  

    /** 
     * Compress by quality,  and generate image to the path specified 
     *  
     * @param image 
     * @param outPath 
     * @param maxSize target will be compressed to be smaller than this size.(kb) 
     * @throws IOException  
     */  
    public void compressAndGenImage(Bitmap image, String outPath, int maxSize) throws IOException {  
        ByteArrayOutputStream os = new ByteArrayOutputStream();  
        // scale  
        int options = 100;  
        // Store the bitmap into output stream(no compress)  
        image.compress(Bitmap.CompressFormat.JPEG, options, os);    
        // Compress by loop  
        while ( os.toByteArray().length / 1024 > maxSize) {  
            // Clean up os  
            os.reset();  
            // interval 10  
            options -= 10;  
            image.compress(Bitmap.CompressFormat.JPEG, options, os);  
        }  

        // Generate compressed image file  
        FileOutputStream fos = new FileOutputStream(outPath);    
        fos.write(os.toByteArray());    
        fos.flush();    
        fos.close();    
    }  

    /** 
     * Compress by quality,  and generate image to the path specified 
     *  
     * @param imgPath 
     * @param outPath 
     * @param maxSize target will be compressed to be smaller than this size.(kb) 
     * @param needsDelete Whether delete original file after compress 
     * @throws IOException  
     */  
    public void compressAndGenImage(String imgPath, String outPath, int maxSize, boolean needsDelete) throws IOException {  
        compressAndGenImage(getBitmap(imgPath), outPath, maxSize);  

        // Delete original file  
        if (needsDelete) {  
            File file = new File (imgPath);  
            if (file.exists()) {  
                file.delete();  
            }  
        }  
    }  

    /** 
     * Ratio and generate thumb to the path specified 
     *  
     * @param image 
     * @param outPath 
     * @param pixelW target pixel of width 
     * @param pixelH target pixel of height 
     * @throws FileNotFoundException 
     */  
    public void ratioAndGenThumb(Bitmap image, String outPath, float pixelW, float pixelH) throws FileNotFoundException {  
        Bitmap bitmap = ratio(image, pixelW, pixelH);  
        storeImage( bitmap, outPath);  
    }  

    /** 
     * Ratio and generate thumb to the path specified 
     *  
     * @param image 
     * @param outPath 
     * @param pixelW target pixel of width 
     * @param pixelH target pixel of height 
     * @param needsDelete Whether delete original file after compress 
     * @throws FileNotFoundException 
     */  
    public void ratioAndGenThumb(String imgPath, String outPath, float pixelW, float pixelH, boolean needsDelete) throws FileNotFoundException {  
        Bitmap bitmap = ratio(imgPath, pixelW, pixelH);  
        storeImage( bitmap, outPath);  

        // Delete original file  
                if (needsDelete) {  
                    File file = new File (imgPath);  
                    if (file.exists()) {  
                        file.delete();  
                    }  
                }  
    }  

}  

转载http://blog.youkuaiyun.com/jdsjlzx/article/details/44228935