Java图片压缩三种高效压缩方案详细解析

java public static void extracted2() { '
string path = "c:\test.jpg"; 
string savepath = "d:\compressed.jpg"; 
int maxwidth = 800; 
int maxheight = 600; 
compressimage(new file(path), new file(savepath), maxwidth, maxheight); 
}
compressimage 写法为kotlin语法法，需要自己转换
fun compressimage(inputfile: file, outputfile: file, maxwidth: int, maxheight: int) {
        try {
            val image = imageio.read(inputfile)
            val originalwidth = image.width
            val originalheight = image.height
            var newwidth = originalwidth
            var newheight = originalheight

            // 计算新的宽度和高度，保持比例
            if (originalwidth > maxwidth || originalheight > maxheight) {
                val ratio = math.min(maxwidth.todouble() / originalwidth, maxheight.todouble() / originalheight)
                newwidth = (originalwidth * ratio).toint()
                newheight = (originalheight * ratio).toint()
            }

            val resizedimage = bufferedimage(newwidth, newheight, bufferedimage.type_int_rgb)
            resizedimage.creategraphics().apply {
                drawimage(image.getscaledinstance(newwidth, newheight, java.awt.image.scale_smooth), 0, 0, null)
                dispose()
            }

            // 确保输出目录存在
            val outputpath: path = paths.get(outputfile.parent)
            if (!files.exists(outputpath)) {
                files.createdirectories(outputpath)
            }

            imageio.write(resizedimage, "jpg", outputfile)
        } catch (e: ioexception) {
            e.printstacktrace()
        }
    }

java public static void extracted4() { 
	for (int i = 1; i <=10; i++) { 
		float quality = 0.1f * i; 
		compressimage(inputfile, outputfile, quality); 
	} 
}
public static void compressimage(file inputfile, file outputfile, float quality) throws ioexception {
        // 读取图片
        bufferedimage image = imageio.read(inputfile);

        // 获取图片写入器
        iterator<imagewriter> writers = imageio.getimagewritersbyformatname("webp");
        imagewriter writer = writers.next();

        // 设置写入器的输出目标
        imageoutputstream ios = imageio.createimageoutputstream(outputfile);
        writer.setoutput(ios);

        // 创建图片写入器配置
        iioimage imageio = new iioimage(image, null, null);
        imagewriteparam param = writer.getdefaultwriteparam();

        // 设置压缩质量
        if (param.canwritecompressed()) {
            param.setcompressionmode(imagewriteparam.mode_explicit);
            param.setcompressionquality(quality);
        }

        // 写入图片
        writer.write(null, imageio, param);

        // 关闭资源
        ios.close();
        writer.dispose();
    }

public static void extracted6() {
        string path = "c:\\users\\美众\\pictures\\test2.jpg";
        for (int i = 1; i <=10; i++) {
            float quality = 0.0f + i * 0.1f;
            system.out.println("quality:" + quality);
            string savepath = "d:\\save\\test2-webp-"+quality+".jpg";
            file inputfile = new file(path); // 原始图片文件
            file outputfile = new file(savepath);
            try {
                jpg2webp(inputfile, outputfile,quality);
            } catch (exception e) {
                throw new runtimeexception(e);
            }
        }
    }
public static void jpg2webp(file oldfile, file newfile,float quality){
        try {
            // 获取原始文件的编码
            bufferedimage image = imageio.read(oldfile);
            // 创建webp imagewriter实例
            imagewriter writer = imageio.getimagewritersbymimetype("image/webp").next();
            // 配置编码参数
            webpwriteparam writeparam = new webpwriteparam(writer.getlocale());
            // 设置压缩模式
            writeparam.setcompressionmode(webpwriteparam.mode_explicit);
            system.out.println("getcompressiontypes:"+json.tojson(writeparam.getcompressiontypes()));
//            "lossy"-有损,"lossless"-无损
            writeparam.setcompressiontype(writeparam.getcompressiontypes()[0]);
            writeparam.setcompressionquality(quality);
            // 配置imagewriter输出
            writer.setoutput(new fileimageoutputstream(newfile));
            // 进行编码，重新生成新图片
            writer.write(null, new iioimage(image, null, null), writeparam);
            system.out.println("jpg文件转成webp格式成功");
        } catch (filenotfoundexception e) {
            e.printstacktrace();
        } catch (ioexception e) {
            e.printstacktrace();
        }
    }