Java9多分辨率ImageAPI

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在Java 9中，引入了新的多分辨率图像API，该API支持具有不同分辨率变量的多个图像。以下是多分辨率图像的主要操作。

Image getResolutionVariant(double destImageWidth，double destImageHeight)- 获取特定图像，该图像是在指定尺寸下代表此图像的最佳变体。
List<Image> getResolutionVariants() - 获取所有分辨率变量的可读列表。

import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;
import java.util.ArrayList;
import java.util.List;
import java.awt.Image;
import java.awt.image.MultiResolutionImage;
import java.awt.image.BaseMultiResolutionImage;

import javax.imageio.ImageIO;

public class Tester {
   public static void main(String[] args) throws IOException, MalformedURLException {

      List<String> imgUrls=List.of("http://www.learnfk.com/java9/images/logo.png",
         "http://www.learnfk.com/java9/images/mini_logo.png",
         "http://www.learnfk.com/java9/images/large_logo.png");

      List<Image> images=new ArrayList<Image>();

      for (String url : imgUrls) {
         images.add(ImageIO.read(new URL(url)));
      }

      //将所有图像读入一个多分辨率图像
      MultiResolutionImage multiResolutionImage=
         new BaseMultiResolutionImage(images.toArray(new Image[0]));

      //获取所有图像的变体
      List<Image> variants=multiResolutionImage.getResolutionVariants();

      System.out.println("Total number of images: " + variants.size());

      for (Image img : variants) {
         System.out.println(img);
      }

      //获取每个指示大小的分辨率特定图像变体
      Image variant1=multiResolutionImage.getResolutionVariant(156, 45);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 
         156, 45, variant1.getWidth(null), variant1.getHeight(null));

      Image variant2=multiResolutionImage.getResolutionVariant(311, 89);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 311, 89, 
         variant2.getWidth(null), variant2.getHeight(null));

      Image variant3=multiResolutionImage.getResolutionVariant(622, 178);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 622, 178, 
         variant3.getWidth(null), variant3.getHeight(null));

      Image variant4=multiResolutionImage.getResolutionVariant(300, 300);
      System.out.printf("\nImage for destination[%d,%d]: [%d,%d]", 300, 300, 
         variant4.getWidth(null), variant4.getHeight(null));
   }  
}

运行上面代码输出

Total number of images: 3
BufferedImage@7ce6a65d: type=6 ColorModel: #pixelBits=32 numComponents=4 
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency=3 
has alpha=true isAlphaPre=false ByteInterleavedRaster: width =311 
height=89 #numDataElements 4 dataOff[0]=3

BufferedImage@4c762604: type=6 ColorModel: #pixelBits=32 numComponents=4 
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency=3 
has alpha=true isAlphaPre=false ByteInterleavedRaster: width =156 
height=45 #numDataElements 4 dataOff[0]=3

BufferedImage@2641e737: type=6 ColorModel: #pixelBits=32 numComponents=4 
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency=3 
has alpha=true isAlphaPre=false ByteInterleavedRaster: width =622 
height=178 #numDataElements 4 dataOff[0]=3

Image for destination[156,45]: [311,89]
Image for destination[311,89]: [311,89]
Image for destination[622,178]: [622,178]
Image for destination[300,300]: [622,178]