我要评论1：使用thumbnailator
thumbnailator是java的开源图像大小调整库，它使用渐进式双线性缩放。它支持jpg，bmp，jpeg，wbmp，png和gif。
通过将以下maven依赖项添加到我们的pom.xml中，将其包括在我们的项目中：
pom.xml
<dependency>
<groupid>net.coobird</groupid>
<artifactid>thumbnailator</artifactid>
<version>0.4.11</version>
</dependency>
工具类thumbnailsutils
import net.coobird.thumbnailator.thumbnails;
import org.slf4j.logger;
import org.slf4j.loggerfactory;
import javax.imageio.imageio;
import java.awt.image.bufferedimage;
import java.io.bytearrayinputstream;
import java.io.bytearrayoutputstream;
import java.io.ioexception;
public class thumbnailsutils{
private static final logger logger = loggerfactory.getlogger(thumbnailsutils.class);
/**
* 通过bufferedimage图片流调整图片大小
*/
public static bufferedimage resizeimageone(bufferedimage originalimage, int targetwidth, int targetheight) throws exception {
bytearrayoutputstream outputstream = new bytearrayoutputstream();
thumbnails.of(originalimage)
.size(targetwidth, targetheight)
.outputformat("jpeg")
.outputquality(1)
.tooutputstream(outputstream);
byte[] data = outputstream.tobytearray();
bytearrayinputstream inputstream = new bytearrayinputstream(data);
return imageio.read(inputstream);
}
/**
* bufferedimage图片流转byte[]数组
*/
public static byte[] imagetobytes(bufferedimage bimage) {
bytearrayoutputstream out = new bytearrayoutputstream();
try {
imageio.write(bimage, "jpg", out);
} catch (ioexception e) {
logger.error("错误信息: ", e);
}
return out.tobytearray();
}
/**
* byte[]数组转bufferedimage图片流
*/
private static bufferedimage bytestobufferedimage(byte[] imagebyte) {
bytearrayinputstream in = new bytearrayinputstream(imagebyte);
bufferedimage image = null;
try {
image = imageio.read(in);
} catch (ioexception e) {
logger.error("错误信息: ", e);
}
return image;
}
}
2：graphics2d 自带的方法
public static bufferedimage scaleimage(bufferedimage originalimage, int targetwidth, int targetheight) {
int type = originalimage.gettype() == 0 ? bufferedimage.type_int_argb : originalimage.gettype();
bufferedimage scaledimage = new bufferedimage(targetwidth, targetheight, type);
graphics2d g = scaledimage.creategraphics();
// calculate the ratio between the original and scaled image size
double scalex = (double) targetwidth / originalimage.getwidth();
double scaley = (double) targetheight / originalimage.getheight();
double scale = math.min(scalex, scaley);
// now we perform the actual scaling
int newwidth = (int) (originalimage.getwidth() * scale);
int newheight = (int) (originalimage.getheight() * scale);
int x = (targetwidth - newwidth) / 2;
int y = (targetheight - newheight) / 2;
g.drawimage(originalimage.getscaledinstance(newwidth, newheight, image.scale_smooth), x, y, null);
g.dispose();
return scaledimage;
} public static void main(string[] args) throws exception {
// 读取原始图片
file originalfile = new file("d:\\test1\\schoollogo.png");
bufferedimage originalimage = imageio.read(originalfile);
// 设定目标宽高
int targetwidth = 1000; // 两倍放大
int targetheight = 1000; // 两倍放大
// 调用 resizeimageone 方法进行放大
bufferedimage resizedimage = thumbnailsutils.scaleimage(originalimage, targetwidth, targetheight);
// 将放大后的图片保存到文件
file outputfile = new file("d:\\test1\\big.png");
imageio.write(resizedimage, "png", outputfile);
}3：前两种我在使用 imagecombiner 项目的时候 不生效；
// 创建新的 bufferedimage，并设置绘制质量
bufferedimage resizedimage = new bufferedimage(newwidth, newheight, bufferedimage.type_int_rgb);
graphics2d g2d = resizedimage.creategraphics();
g2d.setrenderinghint(renderinghints.key_interpolation, renderinghints.value_interpolation_bilinear);
// 绘制原始图像到新的 bufferedimage，并进行缩放
image scaledimage = image.getscaledinstance(newwidth, newheight, image.scale_smooth);
g2d.drawimage(scaledimage, 0, 0, null);
g2d.dispose();
// 保存新的图片
string outputimagepath = "c:\\users\\up1.jpg"; // 替换为实际的输出路径
imageio.write(resizedimage, "jpg", new file(outputimagepath));
system.out.println("图片尺寸调整完成！");总结
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