最近项目中需要判断上传的图片必须是png,jpg,gif三种格式的图片,并且当图片的宽度大于600px时,压缩图片至600px,并且等比例的压缩图片的高度。
具体的实现形式:
大致的思路是:
- 判断根据文件名判断图片的格式是否是png,jpg,gif三种图片文件 定义了 方法
- 如果是的,则进入到scaleImage(String imgSrc, String imgDist)方法中判断图片大小,如果图片大小合适,则直接利用copyFile(File fromFile, File toFile)方法复制图片
- 在缩放图片中利用到java.awt里面的几个类,并且利用BufferedImage可以加快图片的压缩速度。
package com.ctbri.test;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.*;
public class PictureChange {
static String suffix = "";
public static void main(String[] args) {
String newfilebase = "E:/A_xia_program/image/";
File file = new File(newfilebase + 1);
File[] oldfiles = file.listFiles();
for (File file2 : oldfiles) {
if (isImageFile(file2)) {
if (!scaleImage(newfilebase + 1 + "/" + file2.getName(), newfilebase + 11 + "/" + file2.getName())) {
System.out.println(file2.getName()+"转化成功!");
}
}
}
}
public static boolean isImageFile(File file) {
String fileName = file.getName();
//获取文件名的后缀,可以将后缀定义为类变量,共后面的函数使用
suffix = fileName.substring(fileName.lastIndexOf(".") + 1, fileName.length());
// 声明图片后缀名数组
if (!suffix.matches("^[(jpg)|(png)|(gif)]+$")) {
System.out.println("请输入png,jpg,gif格式的图片");
return false;
}
return true;
}
public static boolean scaleImage(String imgSrc, String imgDist) {
try {
File file = new File(imgSrc);
if (!file.exists()) {
return false;
}
InputStream is = new FileInputStream(file);
Image src = ImageIO.read(is);
if (src.getWidth(null) <= 600) {
File tofile = new File(imgDist);
copyFile(file, tofile);
is.close();
return true;
}
//获取源文件的宽高
int imageWidth = ((BufferedImage) src).getWidth();
int imageHeight = ((BufferedImage) src).getHeight();
double scale = (double) 600 / imageWidth;
//计算等比例压缩之后的狂傲
int newWidth = (int) (imageWidth * scale);
int newHeight = (int) (imageHeight * scale);
BufferedImage newImage = scaleImage((BufferedImage) src, scale, newWidth, newHeight);
File file_out = new File(imgDist);
ImageIO.write(newImage, suffix, file_out);
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return false;
}
//用于具体的转化
public static BufferedImage scaleImage(BufferedImage bufferedImage, double scale, int width, int height) {
int imageWidth = bufferedImage.getWidth();
int imageHeight = bufferedImage.getHeight();
AffineTransform scaleTransform = AffineTransform.getScaleInstance(scale, scale);
AffineTransformOp bilinearScaleOp = new AffineTransformOp(scaleTransform, AffineTransformOp.TYPE_BILINEAR);
return bilinearScaleOp.filter(bufferedImage, new BufferedImage(width, height, bufferedImage.getType()));
}
//复制文件
public static void copyFile(File fromFile, File toFile) throws IOException {
FileInputStream ins = new FileInputStream(fromFile);
FileOutputStream out = new FileOutputStream(toFile);
byte[] b = new byte[1024];
int n = 0;
while ((n = ins.read(b)) != -1) {
out.write(b, 0, n);
}
ins.close();
out.close();
}
}