根据项目需求整理了一下图片压缩的方法；
1、前端js压缩，base64压缩
function dealImage(base64, w, callback) {
var newImage = new Image();
var quality = 0.6; //压缩系数0-1之间
newImage.src = base64;
newImage.setAttribute("crossOrigin", 'Anonymous'); //url为外域时需要
var imgWidth, imgHeight;
newImage.onload = function () {
imgWidth = this.width;
imgHeight = this.height;
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
if (Math.max(imgWidth, imgHeight) > w) {
if (imgWidth > imgHeight) {
canvas.width = w;
canvas.height = w * imgHeight / imgWidth;
} else {
canvas.height = w;
canvas.width = w * imgWidth / imgHeight;
}
} else {
canvas.width = imgWidth;
canvas.height = imgHeight;
quality = 0.6;
}
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.drawImage(this, 0, 0, canvas.width, canvas.height);
var base64 = canvas.toDataURL("image/jpeg", quality); //压缩语句
// 如想确保图片压缩到自己想要的尺寸,如要求在50-150kb之间，请加以下语句，quality初始值根据情况自定
// while (base64.length / 1024 > 150) {
// quality -= 0.01;
// base64 = canvas.toDataURL("image/jpeg", quality);
// }
// 防止最后一次压缩低于最低尺寸，只要quality递减合理，无需考虑
// while (base64.length / 1024 < 50) {
// quality += 0.001;
// base64 = canvas.toDataURL("image/jpeg", quality);
// }
callback(base64);//必须通过回调函数返回，否则无法及时拿到该值
}
}
//使用压缩
dealImage(oldBase64, 800, printing);
function printing(base64) {
console.log("压缩后", base64.length / 1024)
}
2、后台base64压缩
import com.sun.syndication.io.impl.Base64;
import net.coobird.thumbnailator.Thumbnails;
import net.coobird.thumbnailator.geometry.Positions;
import sun.misc.BASE64Decoder;
public static String resizeImageTo40K(String base64Img) {
try {
BufferedImage src = base64String2BufferedImage(base64Img);
BufferedImage output = Thumbnails.of(src).size(src.getWidth()/3, src.getHeight()/3).asBufferedImage();
String base64 = imageToBase64(output);
if (base64.length() - base64.length() / 8 * 2 > 40000) {
output = Thumbnails.of(output).scale(1/(base64.length()/40000)).asBufferedImage();
base64 = imageToBase64(output);
}
return base64;
} catch (Exception e) {
return base64Img;
}
}
public static BufferedImage base64String2BufferedImage(String base64string) {
BufferedImage image = null;
try {
InputStream stream = BaseToInputStream(base64string);
image = ImageIO.read(stream);
} catch (IOException e) {
// LOG.info("");
}
return image;
}
public static String imageToBase64(BufferedImage bufferedImage) {
Base64 encoder = new Base64();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
ImageIO.write(bufferedImage, "jpg", baos);
} catch (IOException e) {
// LOG.info("");
System.out.println(e);
}
return new String(encoder.encode((baos.toByteArray())));
}
private static InputStream BaseToInputStream(String base64string){
ByteArrayInputStream stream = null;
try {
BASE64Decoder decoder = new BASE64Decoder();
byte[] bytes1 = decoder.decodeBuffer(base64string);
stream = new ByteArrayInputStream(bytes1);
} catch (Exception e) {
// TODO: handle exception
}
return stream;
}
//base64压缩
public static void main(String[] args){
String base64="";
String s=resizeImageTo40K(base64);
System.out.println(s);
}
3、后台java 路径压缩；
public class ThumbnailatorTest {
/**
*
* @param args
* @throws IOException
*/
// public static void main(String[] args) throws IOException {
// ThumbnailatorTest thumbnailatorTest = new ThumbnailatorTest();
//// thumbnailatorTest.test1();
//// thumbnailatorTest.test2();
//// thumbnailatorTest.test3();
//// thumbnailatorTest.test4();
//// thumbnailatorTest.test5();
//// thumbnailatorTest.test6();
//// thumbnailatorTest.test7();
//// thumbnailatorTest.test8();
//// thumbnailatorTest.test9();
// }
/**
* 指定大小进行缩放
*
* @throws IOException
*/
private void test1() throws IOException {
/*
* size(width,height) 若图片横比200小，高比300小，不变
* 若图片横比200小，高比300大，高缩小到300，图片比例不变 若图片横比200大，高比300小，横缩小到200，图片比例不变
* 若图片横比200大，高比300大，图片按比例缩小，横为200或高为300
*/
Thumbnails.of("C:\\Users\\Administrator\\Downloads\\www.jpg").size(200, 300).toFile("C:\\Users\\Administrator\\Desktop\\www_200x300.jpg");
// Thumbnails.of("C:\\Users\\Administrator\\Desktop\\02e853da68681e43fe198c99280861ef.jpg").size(2560, 2048).toFile("C:/image_2560x2048.jpg");
}
/**
* 按照比例进行缩放
*
* @throws IOException
*/
private void test2() throws IOException {
/**
* scale(比例)
*/
Thumbnails.of("C:\\Users\\Administrator\\Desktop\\02e853da68681e43fe198c99280861ef.jpg").scale(0.25f).toFile("C:\\Users\\Administrator\\Desktop\\image_25%.jpg");
// Thumbnails.of("images/test.jpg").scale(1.10f).toFile("C:/image_110%.jpg");
}
/**
* 不按照比例，指定大小进行缩放
*
* @throws IOException
*/
private void test3() throws IOException {
/**
* keepAspectRatio(false) 默认是按照比例缩放的
*/
Thumbnails.of("C:\\Users\\Administrator\\Desktop\\02e853da68681e43fe198c99280861ef.jpg").size(120, 120).keepAspectRatio(false).toFile("C:\\Users\\Administrator\\Desktop\\image_120x120.jpg");
}
/**
* 旋转
*
* @throws IOException
*/
private void test4() throws IOException {
/**
* rotate(角度),正数：顺时针 负数：逆时针
*/
Thumbnails.of("images/test.jpg").size(1280, 1024).rotate(90).toFile("C:/image+90.jpg");
Thumbnails.of("images/test.jpg").size(1280, 1024).rotate(-90).toFile("C:/iamge-90.jpg");
}
/**
* 水印
*
* @throws IOException
*/
private void test5() throws IOException {
/**
* watermark(位置，水印图，透明度)
*/
Thumbnails.of("images/test.jpg").size(1280, 1024).watermark(Positions.BOTTOM_RIGHT, ImageIO.read(new File("images/watermark.png")), 0.5f)
.outputQuality(0.8f).toFile("C:/image_watermark_bottom_right.jpg");
Thumbnails.of("images/test.jpg").size(1280, 1024).watermark(Positions.CENTER, ImageIO.read(new File("images/watermark.png")), 0.5f)
.outputQuality(0.8f).toFile("C:/image_watermark_center.jpg");
}
/**
* 裁剪
*
* @throws IOException
*/
private void test6() throws IOException {
/**
* 图片中心400*400的区域
*/
Thumbnails.of("images/test.jpg").sourceRegion(Positions.CENTER, 400, 400).size(200, 200).keepAspectRatio(false)
.toFile("C:/image_region_center.jpg");
/**
* 图片右下400*400的区域
*/
Thumbnails.of("images/test.jpg").sourceRegion(Positions.BOTTOM_RIGHT, 400, 400).size(200, 200).keepAspectRatio(false)
.toFile("C:/image_region_bootom_right.jpg");
/**
* 指定坐标
*/
Thumbnails.of("images/test.jpg").sourceRegion(600, 500, 400, 400).size(200, 200).keepAspectRatio(false).toFile("C:/image_region_coord.jpg");
}
/**
* 转化图像格式
*
* @throws IOException
*/
private void test7() throws IOException {
/**
* outputFormat(图像格式)
*/
Thumbnails.of("images/test.jpg").size(1280, 1024).outputFormat("png").toFile("C:/image_1280x1024.png");
Thumbnails.of("images/test.jpg").size(1280, 1024).outputFormat("gif").toFile("C:/image_1280x1024.gif");
}
/**
* 输出到OutputStream
*
* @throws IOException
*/
private void test8() throws IOException {
/**
* toOutputStream(流对象)
*/
OutputStream os = new FileOutputStream("C:/image_1280x1024_OutputStream.png");
Thumbnails.of("images/test.jpg").size(1280, 1024).toOutputStream(os);
}
/**
* 输出到BufferedImage
*
* @throws IOException
*/
private void test9() throws IOException {
/**
* asBufferedImage() 返回BufferedImage
*/
BufferedImage thumbnail = Thumbnails.of("images/test.jpg").size(1280, 1024).asBufferedImage();
ImageIO.write(thumbnail, "jpg", new File("C:/image_1280x1024_BufferedImage.jpg"));
}
注：谷歌压缩方法其中有个bug，基于ps 格式图片会有转换问题，需要导入其中包，代码无需修改：
jar包下载可以从：https://mvnrepository.com/