Android 图片压缩实现过程代码
Android图片压缩非两种，一种质量压缩，一种像素压缩，前者多用于图片上传时，后者多用于本地图片展示缩略图时。总结并记录一下，方便以后使用。
具体的分析可以参考这篇文章，http://www.codeceo.com/article/android-image-compression.html
/**
* Image compress factory class
*/
public class ImageUtils {
/**
* Get bitmap from specified image path
*
* @param imgPath image path
* @return Bitmap
*/
public Bitmap getBitmap(String imgPath) {
// Get bitmap through image path
BitmapFactory.Options newOpts = new BitmapFactory.Options();
newOpts.inJustDecodeBounds = false;
// 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 static 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
BitmapFactory.decodeFile(imgPath, newOpts);
int originalWidth = newOpts.outWidth;
int originalHeight = newOpts.outHeight;
// 想要缩放的目标尺寸
float convertedWidth = pixelW;// 设置宽度为120f，可以明显看到图片缩小了
float convertedHeight = pixelH;// 设置高度为240f时，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 ratio = 1; //ratio=1表示不缩放
if (originalWidth > originalHeight && originalWidth > convertedWidth) { //如果宽度大的话根据宽度固定大小缩放
ratio = (int) (newOpts.outWidth / convertedWidth);
} else if (originalWidth < originalHeight && originalHeight > convertedHeight) { //如果高度高的话根据高度固定大小缩放
ratio = (int) (newOpts.outHeight / convertedHeight);
}
if (ratio <= 0) {
ratio = 1;
}
newOpts.inJustDecodeBounds = false;
newOpts.inSampleSize = ratio;//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 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 byteArrayOutputStream = new ByteArrayOutputStream();
image.compress(Bitmap.CompressFormat.JPEG, 100, byteArrayOutputStream);
if (byteArrayOutputStream.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
byteArrayOutputStream.reset();//重置baos即清空baos
image.compress(Bitmap.CompressFormat.JPEG, 50, byteArrayOutputStream);//这里压缩50%，把压缩后的数据存放到baos中
}
ByteArrayInputStream byteArrayInputStream;
// 开始压缩图片，注意此时已经把options.inJustDecodeBounds 设回false了
byteArrayInputStream = new ByteArrayInputStream(byteArrayOutputStream.toByteArray());
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;
BitmapFactory.decodeStream(byteArrayInputStream, null, newOpts);
int originalWidth = image.getWidth();
int originalHeight = image.getHeight();
// 想要缩放的目标尺寸
float convertedWidth = pixelW;// 设置宽度为120f，可以明显看到图片缩小了
float convertedHeight = pixelH;// 设置高度为240f时，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 ratio = 1; //ratio=1表示不缩放
if (originalWidth > originalHeight && originalWidth > convertedWidth) { //如果宽度大的话根据宽度固定大小缩放
ratio = (int) (newOpts.outWidth / convertedWidth);
} else if (originalWidth < originalHeight && originalHeight > convertedHeight) { //如果高度高的话根据高度固定大小缩放
ratio = (int) (newOpts.outHeight / convertedHeight);
}
if (ratio <= 0) {
ratio = 1;
}
newOpts.inJustDecodeBounds = false; //注意此时已经把options.inJustDecodeBounds 设回false了
newOpts.inSampleSize = ratio; //设置缩放比例
return BitmapFactory.decodeStream(byteArrayInputStream, null, newOpts);
}
/**
* Compress by quality, and generate image to the path specified
* Use to upload
*
* @param image
* @param outPath
* @param maxSize target will be compressed to be smaller than this size.(kb)
* @throws IOException
*/
public static 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;
if (options < 0) {
options = 0;
image.compress(Bitmap.CompressFormat.JPEG, options, os);
break;
}
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 imgPath
* @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();
}
}
}
/**
* 根据路径获取图片资源（已缩放）
*
* @param url 图片存储路径
* @param width 缩放的宽度
* @param height 缩放的高度
* @return
*/
public static Bitmap getBitmapFromUrl(String url, double width, double height) {
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true; // 设置了此属性一定要记得将值设置为false
Bitmap bitmap = BitmapFactory.decodeFile(url);
// 防止OOM发生
options.inJustDecodeBounds = false;
int mWidth = bitmap.getWidth();
int mHeight = bitmap.getHeight();
Matrix matrix = new Matrix();
float scaleWidth = 1;
float scaleHeight = 1;
// 按照固定宽高进行缩放
// 这里希望知道照片是横屏拍摄还是竖屏拍摄
// 因为两种方式宽高不同，缩放效果就会不同
// 这里用了比较笨的方式
if (mWidth <= mHeight) {
scaleWidth = (float) (width / mWidth);
scaleHeight = (float) (height / mHeight);
} else {
scaleWidth = (float) (height / mWidth);
scaleHeight = (float) (width / mHeight);
}
// 按照固定大小对图片进行缩放
matrix.postScale(scaleWidth, scaleHeight);
Bitmap newBitmap = Bitmap.createBitmap(bitmap, 0, 0, mWidth, mHeight, matrix, true);
// 用完了记得回收
bitmap.recycle();
try {
storeImage(newBitmap, url);
} catch (FileNotFoundException e) {
e.printStackTrace();
}
return newBitmap;
}
}