Java 中图片压缩处理的解决方案

package com.example.util;
import java.awt.image.BufferedImage;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.imageio.ImageIO;
/**
 * 图片压缩
 * @author 86183
 *
 */
@SuppressWarnings("restriction")
public class ImgCompress {
	static BufferedImage img = null;
	public static void main(String[] args) throws IOException {
		String fromPic = "C:\\Users\\86183\\Pictures\\儿童节插画手绘人物.png";
		String toPic = "C:\\Users\\86183\\Pictures\\儿童节插画手绘人物_min.png";
		ImgCompress imgCom = new ImgCompress(fromPic );
		imgCom.resize(400, 400, toPic);
	}
	/**
	* 构造函数
	*/
	public ImgCompress(String fileName) throws IOException {
	     File file = new File(fileName);// 读入文件
	     img = ImageIO.read(file);      // 构造Image对象
	}
	/**
	 * 强制压缩/放大图片到固定的大小
	 *
	 * @param w int 新宽度
	 * @param h int 新高度
	 */
	public void resize(int w, int h, String toPic) throws IOException {
	// SCALE_SMOOTH 的缩略算法 生成缩略图片的平滑度的 优先级比速度高 生成的图片质量比较好 但速度慢
	    BufferedImage image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
	    image.getGraphics().drawImage(img, 0, 0, w, h, null); // 绘制缩小后的图
	    File destFile = new File(toPic);
	    FileOutputStream out = new FileOutputStream(destFile); // 输出到文件流
	    // 可以正常实现bmp、png、gif转jpg
	    JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
	    encoder.encode(image); // JPEG编码
	    out.close();
	}
}

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

<dependency>
    <groupId>jdk.tools</groupId>
    <artifactId>jdk.tools</artifactId>
    <version>${java.version}</version>
    <scope>system</scope>
    <systemPath>${java.home}/lib/tools.jar</systemPath>
</dependency>

mvn package -Dmaven.compiler.includeJavaxPackages=true

<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<configuration>
					<source>${java.version}</source>
					<target>${java.version}</target>
					<encoding>UTF-8</encoding>
					<compilerArguments>
                       <verbose />
                       <bootclasspath>${java.home}/lib/rt.jar;${java.home}/lib/jce.jar</bootclasspath>
                   </compilerArguments>
				</configuration>
			</plugin>

var fileSize = $("#"+fileId)[0].files[0].size/(1024*1024);
console.log("上传文件大小："+fileSize+"M");

/**
     * 判断文件大小处于限制内
     *
     * @param fileLen 文件长度
     * @param fileSize 限制大小
     * @param fileUnit 限制的单位（B,K,M,G）
     * @return
     */
	public static boolean checkFileSizeIsLimit(Long fileLen, int fileSize, String fileUnit) {
      double fileSizeCom = 0;
      if ("B".equals(fileUnit.toUpperCase())) {
          fileSizeCom = (double) fileLen;
      } else if ("K".equals(fileUnit.toUpperCase())) {
          fileSizeCom = (double) fileLen / 1024;
      } else if ("M".equals(fileUnit.toUpperCase())) {
          fileSizeCom = (double) fileLen / (1024*1024);
      } else if ("G".equals(fileUnit.toUpperCase())) {
          fileSizeCom = (double) fileLen / (1024*1024*1024);
      }
      if (fileSizeCom > fileSize) {
          return false;
      }
      return true;
  }