import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
import com.alibaba.druid.util.StringUtils;
import com.jfinal.kit.StrKit;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGEncodeParam;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
import java.awt.image.BufferedImage;
import java.rmi.registry.Registry;
@SuppressWarnings("restriction")
public class ImageKit {
private final static String[] imgExts=new String[]{"jpg", "jpeg", "png", "bmp"};
public static String getExtName(String fileName){
if(StringUtils.isEmpty(fileName)) return null;
int idx=fileName.lastIndexOf('.');
if(idx!=-1&&(idx+1)<fileName.length()){
return fileName.substring(idx+1);
}else{
return null;
}
}
//通过文件扩展名，是否为支持的图片文件
public static boolean isImageExtName(String fileName){
if(StrKit.isBlank(fileName)){
return false;
}
fileName=fileName.trim().toLowerCase();
String ext=getExtName(fileName);
if(StringUtils.isEmpty(ext)) return false;
for (String str:imgExts){
if(str.equals(ext)){
return true;
}
}
return false;
}
public static final boolean notImageExtName(String fileName){
return !isImageExtName(fileName);
}
public static BufferedImage loadImageFils(String sourceImageFileName){
if(notImageExtName(sourceImageFileName)){
throw new IllegalArgumentException("只支持如下几种类型的图像文件：jpg、jpeg、png、bmp");
}
File sourceImageFile=new File(sourceImageFileName);
if(!sourceImageFile.exists()||!sourceImageFile.isFile()){
throw new IllegalArgumentException("文件不存在");
}
try {
return ImageIO.read(sourceImageFile);
}catch (Exception e){
throw new RuntimeException(e);
}
}
public static void zoom(int maxWidth,File srcFile,String saveFile){
float quality=0.8f;
try {
BufferedImage srcImage = ImageIO.read(srcFile);
int srcWidth = srcImage.getWidth();
int srcHeight = srcImage.getHeight();
if(srcWidth<=maxWidth){
saveWithQuality(srcImage, quality, saveFile);
}else {
float scalingRatio=(float) maxWidth/(float)srcWidth;
float maxHeight = ((float)srcHeight * scalingRatio);
BufferedImage ret=resize(srcImage,maxWidth,(int) maxHeight);
saveWithQuality(ret, quality, saveFile);
}
}catch (Exception e) {
throw new RuntimeException(e);
}
}
public static BufferedImage crop(String sourceImageFile,int left, int top, int width, int height){
if (notImageExtName(sourceImageFile)) {
throw new IllegalArgumentException("只支持如下几种类型的图像文件：jpg、jpeg、png、bmp");
}
try {
BufferedImage bi= ImageIO.read(new File(sourceImageFile));
width = Math.min(width, bi.getWidth());
height = Math.min(height, bi.getHeight());
if(width <= 0) width = bi.getWidth();
if(height <= 0) height = bi.getHeight();
left = Math.min(Math.max(0, left), bi.getWidth() - width);
top = Math.min(Math.max(0, top), bi.getHeight() - height);
return bi.getSubimage(left,top,width,height);
}catch (Exception e){
throw new RuntimeException(e);
}
}
public static void save(BufferedImage bi,String outputImageFile){
FileOutputStream newImage=null;
try {
ImageIO.write(bi,getExtName(outputImageFile),new File(outputImageFile));
} catch(Exception e){
throw new RuntimeException(e);
} finally {
if(newImage!=null){
try {
newImage.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
}
public static BufferedImage resize(BufferedImage bi, int toWidth, int toHeight) {
Graphics g=null;
try {
Image scaledImage = bi.getScaledInstance(toWidth, toHeight, Image.SCALE_SMOOTH);
BufferedImage ret = new BufferedImage(toWidth, toHeight, BufferedImage.TYPE_INT_RGB);
g = ret.getGraphics();
g.drawImage(scaledImage, 0, 0, null);
return ret;
} catch (Exception e) {
throw new RuntimeException(e);
} finally {
if (g != null) {
g.dispose();
}
}
}
public static void saveWithQuality(BufferedImage im, float quality, String outputImageFile){
FileOutputStream newImage = null;
try {
newImage = new FileOutputStream(outputImageFile);
JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(newImage);
JPEGEncodeParam jep = JPEGCodec.getDefaultJPEGEncodeParam(im);
jep.setQuality(quality, true);
encoder.encode(im, jep);
}catch (Exception e) {
throw new RuntimeException(e);
} finally {
if (newImage != null) {
try {newImage.close();} catch (IOException e) {throw new RuntimeException(e);}
}
}
}
}
java图片缩放与裁剪的相关教程结束。
