public static void main(String[] args) {
try {
//图片所在路径
BufferedImage templateImage = ImageIO.read(new File("C:\\Users\\晏丁丁\\Pictures\\图片1.png"))
//原始图片的长度和宽度
int height = templateImage.getHeight()
int width = templateImage.getWidth()
//通过比例压缩
float scale = 0.5f
//通过固定长度压缩
/*int doWithHeight = 100
int dowithWidth = 300*/
//压缩之后的长度和宽度
int doWithHeight = (int) (scale * height)
int dowithWidth = (int) (scale * width)
BufferedImage finalImage = new BufferedImage(dowithWidth, doWithHeight, BufferedImage.TYPE_INT_RGB)
finalImage.getGraphics().drawImage(templateImage.getScaledInstance(dowithWidth, doWithHeight, java.awt.Image.SCALE_SMOOTH), 0, 0, null)
//图片输出路径,以及图片名
FileOutputStream fileOutputStream = new FileOutputStream("D:/image/tupian.jpg")
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(fileOutputStream)
encoder.encode(finalImage)
fileOutputStream.close()
} catch (IOException e) {
e.printStackTrace()
}
}
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文章知
java要实现把一个大图片压缩到指定大小的图片且长宽比不变可以尝试以下操作:
建立一个AffineTransform
AffineTransform(double m00, double m10, double m01, double m11, double m02, double m12)
转换矩阵,缩放比较简单(矩阵可以干很多事情,想做图像处理软件可以研究下)
[ x'] [ m00 m01 m02 ] [ x ] [ m00x + m01y + m02 ]
[ y'] = [ m10 m11 m12 ] [ y ] = [ m10x + m11y + m12 ]
[ 1 ] [ 0 0 1 ] [ 1 ] [ 1 ]
10倍比较难算(根号10啊,当然你想算也行),9倍好点(9的开方是3),m00为1/3,m01为0,m02为0,m10为0,m11为1/3,m12为0。
再建一个AffineTransformOp,把上面的转换传进去
AffineTransformOp(AffineTransform xform, int interpolationType)
最后调用AffineTransformOp的BufferedImage filter(BufferedImage src, BufferedImage dst) ,src传原图片,返回值就是想要的Image,注意是返回值,不是dst,不明白可以看下Java API
可以使用Draw这个类,通过改变像素来改变存储大小,实例如下:
public static boolean compressPic(String srcFilePath, String descFilePath) throws IOException {File file = null
BufferedImage src = null
FileOutputStream out = null
ImageWriter imgWrier
ImageWriteParam imgWriteParams
// 指定写图片的方式为 jpg
imgWrier = ImageIO.getImageWritersByFormatName("jpg").next()
imgWriteParams = new javax.imageio.plugins.jpeg.JPEGImageWriteParam(
null)
// 要使用压缩,必须指定压缩方式为MODE_EXPLICIT
imgWriteParams.setCompressionMode(imgWriteParams.MODE_EXPLICIT)
// 这里指定压缩的程度,参数qality是取值0~1范围内,
imgWriteParams.setCompressionQuality((float) 1)
imgWriteParams.setProgressiveMode(imgWriteParams.MODE_DISABLED)
ColorModel colorModel =ImageIO.read(new File(srcFilePath)).getColorModel()// ColorModel.getRGBdefault()
// 指定压缩时使用的色彩模式
// imgWriteParams.setDestinationType(new javax.imageio.ImageTypeSpecifier(
// colorModel, colorModel.createCompatibleSampleModel(16, 16)))
imgWriteParams.setDestinationType(new javax.imageio.ImageTypeSpecifier(
colorModel, colorModel.createCompatibleSampleModel(16, 16)))
try {
if (isBlank(srcFilePath)) {
return false
} else {
file = new File(srcFilePath)System.out.println(file.length())
src = ImageIO.read(file)
out = new FileOutputStream(descFilePath)
imgWrier.reset()
// 必须先指定 out值,才能调用write方法, ImageOutputStream可以通过任何
// OutputStream构造
imgWrier.setOutput(ImageIO.createImageOutputStream(out))
// 调用write方法,就可以向输入流写图片
imgWrier.write(null, new IIOImage(src, null, null),
imgWriteParams)
out.flush()
out.close()
}
} catch (Exception e) {
e.printStackTrace()
return false
}
return true
}
public static boolean isBlank(String string) {
if (string == null || string.length() == 0 || string.trim().equals("")) {
return true
}
return false
}