java生成图片缩略图

摘要: java生成图片缩略图

package com.maystar.utils;

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;

import javax.imageio.ImageIO;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
* <p>Title: ImageUtil </p>
* <p>Description: 使用JDK原生态类生成图片缩略图和裁剪图片 </p>
* <p>Email: icerainsoft@hotmail.com </p>
* @author Ares
* @date 2014年10月28日 上午10:24:26
*/
public class ImageUtil {

private Logger log = LoggerFactory.getLogger(getClass());

private static String DEFAULT_PREVFIX = "thumb_";
private static Boolean DEFAULT_FORCE = false;

/**
* <p>Title: thumbnailImage</p>
* <p>Description: 根据图片路径生成缩略图 </p>
* @param imagePath 原图片路径
* @param w 缩略图宽
* @param h 缩略图高
* @param prevfix 生成缩略图的前缀
* @param force 是否强制按照宽高生成缩略图(如果为false，则生成最佳比例缩略图)
*/
public void thumbnailImage(File imgFile, int w, int h, String prevfix, boolean force){
if(imgFile.exists()){
try {
// ImageIO 支持的图片类型 : [BMP, bmp, jpg, JPG, wbmp, jpeg, png, PNG, JPEG, WBMP, GIF, gif]
String types = Arrays.toString(ImageIO.getReaderFormatNames());
String suffix = null;
// 获取图片后缀
if(imgFile.getName().indexOf(".") > -1) {
suffix = imgFile.getName().substring(imgFile.getName().lastIndexOf(".") + 1);
}// 类型和图片后缀全部小写，然后判断后缀是否合法
if(suffix == null || types.toLowerCase().indexOf(suffix.toLowerCase()) < 0){
log.error("Sorry, the image suffix is illegal. the standard image suffix is {}." + types);
return ;
}
log.debug("target image's size, width:{}, height:{}.",w,h);
Image img = ImageIO.read(imgFile);
if(!force){
// 根据原图与要求的缩略图比例，找到最合适的缩略图比例
int width = img.getWidth(null);
int height = img.getHeight(null);
if((width*1.0)/w < (height*1.0)/h){
if(width > w){
h = Integer.parseInt(new java.text.DecimalFormat("0").format(height * w/(width*1.0)));
log.debug("change image's height, width:{}, height:{}.",w,h);
}
} else {
if(height > h){
w = Integer.parseInt(new java.text.DecimalFormat("0").format(width * h/(height*1.0)));
log.debug("change image's width, width:{}, height:{}.",w,h);
}
}
}
BufferedImage bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
Graphics g = bi.getGraphics();
g.drawImage(img, 0, 0, w, h, Color.LIGHT_GRAY, null);
g.dispose();
String p = imgFile.getPath();
// 将图片保存在原目录并加上前缀
ImageIO.write(bi, suffix, new File(p.substring(0,p.lastIndexOf(File.separator)) + File.separator + prevfix +imgFile.getName()));
} catch (IOException e) {
log.error("generate thumbnail image failed.",e);
}
}else{
log.warn("the image is not exist.");
}
}

public void thumbnailImage(String imagePath, int w, int h, String prevfix, boolean force){
File imgFile = new File(imagePath);
thumbnailImage(imgFile, w, h, prevfix, force);
}

public void thumbnailImage(String imagePath, int w, int h, boolean force){
thumbnailImage(imagePath, w, h, DEFAULT_PREVFIX, force);
}

public void thumbnailImage(String imagePath, int w, int h){
thumbnailImage(imagePath, w, h, DEFAULT_FORCE);
}

public static void main(String[] args) {
new ImageUtil().thumbnailImage("D:/DSC01145.JPG", 20, 99);
}

}