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();					}				}	}	}

一.图片的存在形式

二.常见的压缩方式