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最近做项目需要图片压缩处理，网上找的方法大都使用了 com.sun.image.codec.jpeg.* 这个包中的JPEGImageEncoder类，引入这个包后一直报错，各种google百度，尝试了各种方法，包括手动引jre中的rt.jar,以及在eclipse中把受访问限制的API提示从ERROR改为WARNING，等等，然而这些都是不好使的，因为后来我发现我的java-7-openjdk-amd64中的rt.jar里边根本就没有com.sun.image.*，貌似这个类在java7中已经被彻底remove了，至少我这个版本是没有了。然后搜了个使用ImageIO类来进行处理的替代方案，代码如下：
import java.io.*;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.awt.*;
//旧的jpeg处理类
//import com.sun.image.codec.jpeg.*;
import com.sun.imageio.plugins.jpeg.*;
import java.awt.image.BufferedImage;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;
import org.w3c.dom.Element;
/**
* @author zhouqz
*/
public class ImgCompressUtil {
/**
* 图片压缩测试
* @param args
*/
public static void main(String args[]){
//读文件夹所有文件进行压缩处理
// String f = "/var/upload_bak/";
// File file = new File(f);
//
// if(file.exists())
// {
// File[] filelist = file.listFiles();
// for(int i = 0;i<filelist.length;i++)
// {
// String n = filelist[i].getName();
// Tosmallerpic(f,filelist[i],"_middle",n,185,160,(float)0.7);
// Tosmallerpic(f,filelist[i],"_small",n,45,45,(float)0.7);
// Tosmallerpic(f,filelist[i],"_smaller",n,116,100,(float)0.7);
// }
// }
//对一个文件进行压缩处理
String url = "/var/upload_bak/";
String name = "31273618df16f1ab32e76c06c2f35852.jpg";
img_change(url,name);
}
public static void img_change(String url,String name)
{
Tosmallerpic(url,new File(url+name),"_middle",name,188,165,(float)0.7);
Tosmallerpic(url,new File(url+name),"_small",name,45,45,(float)0.7);
Tosmallerpic(url,new File(url+name),"_smaller",name,116,100,(float)0.7);
}
/**
*
* @param f 图片所在的文件夹路径
* @param file 图片路径
* @param ext 扩展名
* @param n 图片名
* @param w 目标宽
* @param h 目标高
* @param per 百分比
*/
private static void Tosmallerpic(String f,File file,String ext,String n,int w,int h,float per){
Image src;
try {
src = javax.imageio.ImageIO.read(file); //构造Image对象
String img_midname = f+n.substring(0,n.indexOf("."))+ext+n.substring(n.indexOf("."));
int old_w = src.getWidth(null); //得到源图宽
int old_h = src.getHeight(null);
int new_w = 0;
int new_h = 0; //得到源图长
double w2 = (old_w*1.00)/(w*1.00);
double h2 = (old_h*1.00)/(h*1.00);
//图片跟据长宽留白，成一个正方形图。
BufferedImage oldpic;
if(old_w>old_h)
{
oldpic = new BufferedImage(old_w,old_w,BufferedImage.TYPE_INT_RGB);
}else{if(old_w<old_h){
oldpic = new BufferedImage(old_h,old_h,BufferedImage.TYPE_INT_RGB);
}else{
oldpic = new BufferedImage(old_w,old_h,BufferedImage.TYPE_INT_RGB);
}
}
Graphics2D g = oldpic.createGraphics();
g.setColor(Color.white);
if(old_w>old_h)
{
g.fillRect(0, 0, old_w, old_w);
g.drawImage(src, 0, (old_w - old_h) / 2, old_w, old_h, Color.white, null);
}else{
if(old_w<old_h){
g.fillRect(0,0,old_h,old_h);
g.drawImage(src, (old_h - old_w) / 2, 0, old_w, old_h, Color.white, null);
}else{
//g.fillRect(0,0,old_h,old_h);
g.drawImage(src.getScaledInstance(old_w, old_h, Image.SCALE_SMOOTH), 0,0,null);
}
}
g.dispose();
src = oldpic;
//图片调整为方形结束
if(old_w>w)
new_w = (int)Math.round(old_w/w2);
else
new_w = old_w;
if(old_h>h)
new_h = (int)Math.round(old_h/h2);//计算新图长宽
else
new_h = old_h;
BufferedImage image_to_save = new BufferedImage(new_w,new_h,BufferedImage.TYPE_INT_RGB);
image_to_save.getGraphics().drawImage(src.getScaledInstance(new_w, new_h, Image.SCALE_SMOOTH), 0,0,null);
FileOutputStream fos = new FileOutputStream(img_midname); //输出到文件流
//旧的使用 jpeg classes进行处理的方法
// JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(fos);
// JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam(image_to_save);
/* 压缩质量 */
// jep.setQuality(per, true);
// encoder.encode(image_to_save, jep);
//新的方法
saveAsJPEG(100, image_to_save, per, fos);
fos.close();
} catch (IOException ex) {
Logger.getLogger(Img_Middle.class.getName()).log(Level.SEVERE, null, ex);
}
}
/**
* 以JPEG编码保存图片
* @param dpi 分辨率
* @param image_to_save 要处理的图像图片
* @param JPEGcompression 压缩比
* @param fos 文件输出流
* @throws IOException
*/
public static void saveAsJPEG(Integer dpi ,BufferedImage image_to_save, float JPEGcompression, FileOutputStream fos) throws IOException {
//useful documentation at http://docs.oracle.com/javase/7/docs/api/javax/imageio/metadata/doc-files/jpeg_metadata.html
//useful example program at http://johnbokma.com/java/obtaining-image-metadata.html to output JPEG data
//old jpeg class
//com.sun.image.codec.jpeg.JPEGImageEncoder jpegEncoder = com.sun.image.codec.jpeg.JPEGCodec.createJPEGEncoder(fos);
//com.sun.image.codec.jpeg.JPEGEncodeParam jpegEncodeParam = jpegEncoder.getDefaultJPEGEncodeParam(image_to_save);
// Image writer
JPEGImageWriter imageWriter = (JPEGImageWriter) ImageIO.getImageWritersBySuffix("jpg").next();
ImageOutputStream ios = ImageIO.createImageOutputStream(fos);
imageWriter.setOutput(ios);
//and metadata
IIOMetadata imageMetaData = imageWriter.getDefaultImageMetadata(new ImageTypeSpecifier(image_to_save), null);
if(dpi != null && !dpi.equals("")){
//old metadata
//jpegEncodeParam.setDensityUnit(com.sun.image.codec.jpeg.JPEGEncodeParam.DENSITY_UNIT_DOTS_INCH);
//jpegEncodeParam.setXDensity(dpi);
//jpegEncodeParam.setYDensity(dpi);
//new metadata
Element tree = (Element) imageMetaData.getAsTree("javax_imageio_jpeg_image_1.0");
Element jfif = (Element)tree.getElementsByTagName("app0JFIF").item(0);
jfif.setAttribute("Xdensity", Integer.toString(dpi) );
jfif.setAttribute("Ydensity", Integer.toString(dpi));
}
if(JPEGcompression >= 0 && JPEGcompression <= 1f){
//old compression
//jpegEncodeParam.setQuality(JPEGcompression,false);
// new Compression
JPEGImageWriteParam jpegParams = (JPEGImageWriteParam) imageWriter.getDefaultWriteParam();
jpegParams.setCompressionMode(JPEGImageWriteParam.MODE_EXPLICIT);
jpegParams.setCompressionQuality(JPEGcompression);
}
//old write and clean
//jpegEncoder.encode(image_to_save, jpegEncodeParam);
//new Write and clean up
imageWriter.write(imageMetaData, new IIOImage(image_to_save, null, null), null);
ios.close();
imageWriter.dispose();
}
}
参考：
http://jiangpin1987.iteye.com/blog/749690
https://blog.idrsolutions.com/2012/05/replacing-the-deprecated-java-jpeg-classes-for-java-7/
java图片压缩，使用ImageIO代替JPEGImageEncoder
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原文地址：http://my.oschina.net/JustLoveIT/blog/474004
