package com.hzxc.groupactivity.server.util;
import java.awt.image.BufferedImage;
import java.io.*;
import java.math.BigDecimal;

import javax.imageio.ImageIO;
import net.coobird.thumbnailator.Thumbnails;
import org.apache.commons.lang3.StringUtils;

/**
 * Created by hdwang on 2018/12/13.
 */
public class
 
 PicUtils {
 
    public static void main(String[] args) {
 
        PicUtils.commpressPicForScale("/Users/hdwang/Downloads/1.jpg","/Users/hdwang/Downloads/1_s.jpg", 1000, 0.8,750,1334); // 圖片小於1000kb


    }
 
    /**
      * 根據指定大小和指定精度壓縮圖片
      * 
      * @param srcPath
      *            源圖片地址
      * @param desPath
      *            目標圖片地址
      * 
 
@param desFileSize
      *            指定圖片大小，單位kb
      * @param accuracy
      *            精度，遞歸壓縮的比率，建議小於0.9
     *  @param desMaxWidth
     *             目標最大寬度
     *  @param desMaxHeight
     *             目標最大高度
      * @return 目標文件路徑
      */
    public static String commpressPicForScale(String srcPath, String desPath,
            
 
long desFileSize, double accuracy,int desMaxWidth,int desMaxHeight) {
        if (StringUtils.isEmpty(srcPath) || StringUtils.isEmpty(srcPath)) {
            return null;
        }
        if (!new File(srcPath).exists()) {
            return null;
        }
        try {
            File srcFile = new File(srcPath);
            long srcFileSize = srcFile.length();
            System.out.println("源圖片：" + srcPath + "，大小：" + srcFileSize / 1024
                                        + "kb");
            //獲取圖片信息
            BufferedImage bim = ImageIO.read(srcFile);
            int srcWidth = bim.getWidth();
            int srcHeight = bim.getHeight();

            //先轉換成jpg
            Thumbnails.Builder builder = Thumbnails.of(srcFile).outputFormat("jpg");

            // 指定大小（寬或高超出會才會被縮放）
            if(srcWidth > desMaxWidth || srcHeight > desMaxHeight) {
                builder.size(desMaxWidth, desMaxHeight);
            }else{
                //寬高均小，指定原大小
                builder.size(srcWidth,srcHeight);
            }

            // 寫入到內存
            ByteArrayOutputStream baos = new ByteArrayOutputStream(); //字節輸出流（寫入到內存）
            builder.toOutputStream(baos);

            // 遞歸壓縮，直到目標文件大小小於desFileSize
            byte[] bytes = commpressPicCycle(baos.toByteArray(), desFileSize, accuracy);

            // 輸出到文件
            File desFile = new File(desPath);
            FileOutputStream fos = new FileOutputStream(desFile);
            fos.write(bytes);

            System.out.println("目標圖片：" + desPath + "，大小" + desFile.length() / 1024 + "kb");
            System.out.println("圖片壓縮完成！");
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
        return desPath;
    }
 
    private static byte[] commpressPicCycle(byte[] bytes, long desFileSize, double accuracy) throws IOException {
       // File srcFileJPG = new File(desPath);
        long srcFileSizeJPG = bytes.length;
        // 2、判斷大小，如果小於500kb，不壓縮；如果大於等於500kb，壓縮
        if (srcFileSizeJPG <= desFileSize * 1024) {
            return bytes;
        }
        // 計算寬高
        BufferedImage bim = ImageIO.read(new ByteArrayInputStream(bytes));
        int srcWdith = bim.getWidth();
        int srcHeigth = bim.getHeight();
        int desWidth = new BigDecimal(srcWdith).multiply(
                                new BigDecimal(accuracy)).intValue();
        int desHeight = new BigDecimal(srcHeigth).multiply(
                                new BigDecimal(accuracy)).intValue();

        ByteArrayOutputStream baos = new ByteArrayOutputStream(); //字節輸出流（寫入到內存）
        Thumbnails.of(new ByteArrayInputStream(bytes)).size(desWidth, desHeight).outputQuality(accuracy).toOutputStream(baos);
        return commpressPicCycle(baos.toByteArray(), desFileSize, accuracy);
    }

}

參考文章：

https://blog.csdn.net/qiaqia609/article/details/53171149

https://blog.csdn.net/qiaqia609/article/details/53171149

java圖片壓縮（Thumbnails）