1 纯原生手写图片操作工具类

import java.awt.Dimension;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.image.BufferedImage;
public class RotateImageUtil {public static BufferedImage rotateImage(BufferedImage bufferedImage, int angel) {if (bufferedImage == null) {return null;}if (angel < 0) {// 将负数角度，纠正为正数角度angel = angel + 360;}int imageWidth = bufferedImage.getWidth(null);int imageHeight = bufferedImage.getHeight(null);// 计算重新绘制图片的尺寸Rectangle rectangle = calculatorRotatedSize(new Rectangle(new Dimension(imageWidth, imageHeight)), angel);// 获取原始图片的透明度int type = bufferedImage.getColorModel().getTransparency();BufferedImage newImage = null;newImage = new BufferedImage(rectangle.width, rectangle.height, type);Graphics2D graphics = newImage.createGraphics();// 平移位置graphics.translate((rectangle.width - imageWidth) / 2, (rectangle.height - imageHeight) / 2);// 旋转角度graphics.rotate(Math.toRadians(angel), imageWidth / 2, imageHeight / 2);// 绘图graphics.drawImage(bufferedImage, null, null);return newImage;}public static BufferedImage rotateImage(Image image, int angel) {if (image == null) {return null;}if (angel < 0) {// 将负数角度，纠正为正数角度angel = angel + 360;}int imageWidth = image.getWidth(null);int imageHeight = image.getHeight(null);Rectangle rectangle = calculatorRotatedSize(new Rectangle(new Dimension(imageWidth, imageHeight)), angel);BufferedImage newImage = null;newImage = new BufferedImage(rectangle.width, rectangle.height, BufferedImage.TYPE_INT_RGB);Graphics2D graphics = newImage.createGraphics();graphics.translate((rectangle.width - imageWidth) / 2, (rectangle.height - imageHeight) / 2);graphics.rotate(Math.toRadians(angel), imageWidth / 2, imageHeight / 2);graphics.drawImage(image, null, null);return newImage;}//计算旋转后的尺寸private static Rectangle calculatorRotatedSize(Rectangle src, int angel) {if (angel >= 90) {if (angel / 90 % 2 == 1) {int temp = src.height;src.height = src.width;src.width = temp;}angel = angel % 90;}double r = Math.sqrt(src.height * src.height + src.width * src.width) / 2;double len = 2 * Math.sin(Math.toRadians(angel) / 2) * r;double angel_alpha = (Math.PI - Math.toRadians(angel)) / 2;double angel_dalta_width = Math.atan((double) src.height / src.width);double angel_dalta_height = Math.atan((double) src.width / src.height);int len_dalta_width = (int) (len * Math.cos(Math.PI - angel_alpha - angel_dalta_width));int len_dalta_height = (int) (len * Math.cos(Math.PI - angel_alpha - angel_dalta_height));int des_width = src.width + len_dalta_width * 2;int des_height = src.height + len_dalta_height * 2;return new java.awt.Rectangle(new Dimension(des_width, des_height));}
}

main方法调用

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
public class test {//测试一下，直接抛出异常了，小伙伴们项目中要记住用try···catch···哦public static void main(String[] args) throws Exception {File picture = new File("C:\\Users\\Administrator\\Desktop\\saga.png");BufferedImage sourceImg = ImageIO.read(new FileInputStream(picture));if ( sourceImg.getHeight() > sourceImg.getWidth() ) {//旋转，这里数值代表顺时针，逆时针，各位可以换其他角度玩儿玩儿BufferedImage rotate = RotateImageUtil.rotateImage(sourceImg, -90);ImageIO.write(rotate, "png", new File("D:\\", picture.getName()));InputStream is = new FileInputStream( new File("D:\\", picture.getName()) );byte[] data = new byte[is.available()];is.read(data);is.close();} else {System.out.println(false);}}
}

2 Hutool操作图片

cn.hutoolhutool-all5.1.0

操作图片示例代码：

import cn.hutool.core.img.ImgUtil;
import cn.hutool.core.io.FileUtil;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;public class HutoolImage {public static void main(String[] args)  {//提供两种重载方法，按长宽缩放，按比例缩放ImgUtil.scale(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"),FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal_result.jpg"),0.5f   //图片缩放比例);//图片按一定的尺寸裁剪ImgUtil.cut(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"),FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal_small.jpg"),new Rectangle(200, 200, 100, 100)//裁剪的矩形区域);//按照行列裁剪切片ImgUtil.slice(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"), FileUtil.file("C:\\Users\\DELL\\Desktop\\test\\"), 10, 10);//将图片彩色转黑白色ImgUtil.gray(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"), FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal_black.jpg"));//给图片添加文字水印ImgUtil.pressText(//FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"), //FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal_logo.jpg"), //"版权所有", Color.BLUE, //文字new Font("宋体", Font.BOLD, 100), //字体0, //x坐标修正值。 默认在中间，偏移量相对于中间偏移0, //y坐标修正值。 默认在中间，偏移量相对于中间偏移0.8f//透明度：alpha 必须是范围 [0.0, 1.0] 之内（包含边界值）的一个浮点数字);//旋转图片180度BufferedImage image = null;try {image = (BufferedImage) ImgUtil.rotate(ImageIO.read(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg")), 180);} catch (IOException e) {e.printStackTrace();}ImgUtil.write(image, FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal_tangle.jpg"));//图片水平翻转ImgUtil.flip(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"), FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal_flat.jpg"));//转换图片存储格式ImgUtil.convert(FileUtil.file("C:\\Users\\DELL\\Desktop\\animal.jpg"), FileUtil.file("C:\\Users\\DELL\\Desktop\\Image\\animal.png"));}
}

3 谷歌开源框架Thumbnailator

Thumbnailator 是一个优秀的图片处理的Google开源Java类库。处理效果远比Java API的好。从API提供现有的图像文件和图像对象的类中简化了处理过程，两三行代码就能够从现有图片生成处理后的图片，且允许微调图片的生成方式，同时保持了需要写入的最低限度的代码量。还支持对一个目录的所有图片进行批量处理操作

支持的处理操作：图片缩放，区域裁剪，水印，旋转，保持比例。

另外值得一提的是，Thumbnailator至今仍不断更新，怎么样，感觉很有保障吧！
Thumbnailator官网： http://code.google.com/p/thumbnailator/

文章教程：https://blog.csdn.net/qq_37712731/article/details/118514686

1、指定大小进行缩放

//size(宽度, 高度)/** 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("images/a380_1280x1024.jpg").size(200, 300).toFile("c:/a380_200x300.jpg");Thumbnails.of("images/a380_1280x1024.jpg").size(2560, 2048).toFile("c:/a380_2560x2048.jpg");1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.

2、按照比例进行缩放

//scale(比例)
Thumbnails.of("images/a380_1280x1024.jpg").scale(0.25f).toFile("c:/a380_25%.jpg");Thumbnails.of("images/a380_1280x1024.jpg").scale(1.10f).toFile("c:/a380_110%.jpg");1.2.3.4.5.6.7.8.

3、不按照比例，指定大小进行缩放

//rotate(角度),正数：顺时针负数：逆时针
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).rotate(90).toFile("c:/a380_rotate+90.jpg");Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).rotate(-90).toFile("c:/a380_rotate-90.jpg");1.2.3.4.5.6.7.8.9.10.

//keepAspectRatio(false)默认是按照比例缩放的
Thumbnails.of("images/a380_1280x1024.jpg").size(200,200).keepAspectRatio(false).toFile("c:/a380_200x200.jpg");1.2.3.4.5.

5、水印

//watermark(位置，水印图，透明度)
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).watermark(Positions.BOTTOM_RIGHT,ImageIO.read(newFile("images/watermark.png")),0.5f).outputQuality(0.8f).toFile("c:/a380_watermark_bottom_right.jpg");Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).watermark(Positions.CENTER,ImageIO.read(newFile("images/watermark.png")),0.5f).outputQuality(0.8f).toFile("c:/a380_watermark_center.jpg");1.2.3.4.5.6.7.8.9.10.11.12.

6、裁剪

//sourceRegion()//图片中心400*400的区域
Thumbnails.of("images/a380_1280x1024.jpg").sourceRegion(Positions.CENTER,400,400).size(200,200).keepAspectRatio(false).toFile("c:/a380_region_center.jpg");//图片右下400*400的区域
Thumbnails.of("images/a380_1280x1024.jpg").sourceRegion(Positions.BOTTOM_RIGHT,400,400).size(200,200).keepAspectRatio(false).toFile("c:/a380_region_bootom_right.jpg");//指定坐标
Thumbnails.of("images/a380_1280x1024.jpg").sourceRegion(600,500,400,400).size(200,200).keepAspectRatio(false).toFile("c:/a380_region_coord.jpg");1.2.3.4.5.6.7.8.9.10.11.12.13.14.15.16.17.18.19.20.21.22.

7、转化图像格式

//outputFormat(图像格式)
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).outputFormat("png").toFile("c:/a380_1280x1024.png");Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).outputFormat("gif").toFile("c:/a380_1280x1024.gif");1.2.3.4.5.6.7.8.9.10.

8、输出到OutputStream

//toOutputStream(流对象)
OutputStreamos=newFileOutputStream("c:/a380_1280x1024_OutputStream.png");
Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).toOutputStream(os);1.2.3.4.5.

9、输出到BufferedImage

//asBufferedImage()返回BufferedImage
BufferedImagethumbnail=Thumbnails.of("images/a380_1280x1024.jpg").size(1280,1024).asBufferedImage();
ImageIO.write(thumbnail,"jpg",newFile("c:/a380_1280x1024_BufferedImage.jpg"));

4 总结

谷歌开源框架处理图片实测性能较差，用起来比较方便，建议用Hutool因为只是对awt做的封装不用自己写，性能也高。

原文地址：https://blog.csdn.net/ZGL_cyy/article/details/126680559