java图片缩放一，使用ImageIO代替JPEGImageEncoder

项目中 需要对用户上传的图片进行压缩或者放大处理 在网上找的实例中都是使用的JPEGImageEncoder ( com.sun.image.codec.jpeg.JPEGImageEncoder )类进行的。但是从jdk7
开始 这个类已经被移除了。虽能网友也提供了一些其他的解决方案 但总是觉得不太好用。后来从网上搜索到了 使用ImageIO类替代的方法。 能后自己有做了一些改动。 仅此做些记录 同时也可以让需要的朋友少走些弯路。

具体代码如下：

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageTypeSpecifier;
import javax.imageio.ImageWriter;
import javax.imageio.metadata.IIOMetadata;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;

import org.w3c.dom.Element;

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 = "F:\\FMS_REPLAY_MEDIA\\img\\";
String name  =  "sd456asd.gif";
name = "9d8608c7ea288a691b03ae5e0604de06.jpg";
Tosmallerpic(url,url,name,188,165,(float)0.85);
}

/**
*
* @param srcFilePath 图片所在的文件夹路径
* @param destFilePath 存放路径
* @param name 图片名
* @param w 目标宽
* @param h 目标高
* @param per 百分比
*/
private static void  Tosmallerpic(String srcFilePath,String destFilePath,String name,int w,int h,float per){
Image src;
try {
src  =  javax.imageio.ImageIO.read(new File(srcFilePath+File.separator+name)); //构造Image对象

String img_midname  =  destFilePath + File.separator + "c_"+name;
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("jpeg").next();
ImageWriter imageWriter  =   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();

}

}

参考文章： http://jiangpin1987.iteye.com/blog/749690 https://blog.idrsolutions.com/2012/05/replacing-the-deprecated-java-jpeg-classes-for-java-7/