java图片压缩

图片像素降低

package com.example.demo.线程池.截屏;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import java.awt.image.BufferedImage;
import java.awt.image.ColorModel;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
public class 图片像素降低 {
    public static File run(String  in, float 清晰程度, String 图片尾缀) throws IOException {
        File file=new File(in);
        BufferedImage src = null;
        FileOutputStream out = null;
        ImageWriter imgWrier;
        ImageWriteParam imgWriteParams;
        //System.out.println("开始设定压缩图片参数");
        // 指定写图片的方式为 jpg
        imgWrier = ImageIO.getImageWritersByFormatName(图片尾缀).next();
        imgWriteParams = new javax.imageio.plugins.jpeg.JPEGImageWriteParam(
                null);
        // 要使用压缩，必须指定压缩方式为MODE_EXPLICIT
        imgWriteParams.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
        // 这里指定压缩的程度，参数qality是取值0~1范围内，
        imgWriteParams.setCompressionQuality(清晰程度);
        imgWriteParams.setProgressiveMode(ImageWriteParam.MODE_DISABLED);
        ColorModel colorModel = ImageIO.read(file).getColorModel();// ColorModel.getRGBdefault();
        imgWriteParams.setDestinationType(new javax.imageio.ImageTypeSpecifier(
                colorModel, colorModel.createCompatibleSampleModel(32, 32)));

        //System.out.println("结束设定压缩图片参数");
        if (!file.exists()) {
            System.out.println("Not Found Img File,文件不存在");
            throw new FileNotFoundException("Not Found Img File,文件不存在");
        } else {
            System.out.println("图片转换前大小" + file.length() + "字节");
            src = ImageIO.read(file);
            out = new FileOutputStream(file);
            imgWrier.reset();
            // 必须先指定 out值，才能调用write方法, ImageOutputStream可以通过任何
            // OutputStream构造
            imgWrier.setOutput(ImageIO.createImageOutputStream(out));
            // 调用write方法，就可以向输入流写图片
            imgWrier.write(null, new IIOImage(src, null, null),
                    imgWriteParams);
            out.flush();
            out.close();
            System.out.println("图片转换后大小" + file.length() + "字节");
            return file;
        }
    }

}

图片分辨率降低

package com.example.demo.线程池.截屏;

import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
public class 图片分辨率降低 {

    public static void run(String 绝对路径, int w, int h) throws Exception {
        String dest=绝对路径;

        double wr=0,hr=0;
        File srcFile = new File(绝对路径);
        File destFile = new File(dest);

        BufferedImage bufImg = ImageIO.read(srcFile); //读取图片
        Image Itemp = bufImg.getScaledInstance(w, h, bufImg.SCALE_SMOOTH);//设置缩放目标图片模板

        wr=w*1.0/bufImg.getWidth();     //获取缩放比例
        hr=h*1.0 / bufImg.getHeight();

        AffineTransformOp ato = new AffineTransformOp(AffineTransform.getScaleInstance(wr, hr), null);
        Itemp = ato.filter(bufImg, null);
        try {
            ImageIO.write((BufferedImage) Itemp,dest.substring(dest.lastIndexOf(".")+1), destFile); //写入缩减后的图片
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}

结合截图的使用范例

String 项目根目录 = new File("").getCanonicalPath() ; //                                              ↓这里电脑屏幕缩放比例是150% 就填1.5
截屏 scan=截屏.run(项目根目录+"\src\main\java\com\example\demo\线程池\截屏\","jpg",1.5);

//降低分辨率     ↓这里是图片的绝对路径，就是上面第一个run的第一个参数
图片分辨率降低.run(scan.文件地址.getPath(),  (int) (scan.图片长*0.7)  , (int)(scan.图片宽*0.7)   );
//降低画质,压缩                         取值0~1范围内  清晰程度  数值越小分辨率越低
图片像素降低.run(scan.文件地址.getPath(),(float) 0.1,scan.图片尾缀);