Java 9 引入了多分辨率图像 API，这个 API 支持多个具有不同分辨率变体的图像。此 API 允许一组具有不同分辨率的图像作为单一的多分辨率图像来使用。
考虑以下图像。
这些是三个不同尺寸的标志图像。
为了处理这三个图像，从 Java 9 开始，可以使用多分辨率图像 API 作为单一 API 来获取所有变体或特定要显示的变体。
MultiResolutionImage multiResolutionImage =
new BaseMultiResolutionImage(images.toArray(new Image[0]));
这里的 MultiResolutionImage 和 BaseMultiResolutionImage 类都是 java.awt.image 包的一部分。
以下是多分辨率图像的主要操作：
-
Image getResolutionVariant(double destImageWidth, double destImageHeight) — 获取特定大小的最佳图像变体来表示此逻辑图像。
-
List<Image> getResolutionVariants() — 获取所有分辨率变体的可读列表。
示例 - 获取所有变体
在这个例子中，我们加载了三个图像并将它们存储在 MultiResolutionImage 中。然后使用 getResolutionVariants() 方法检查此多分辨率图像中的所有可用图像变体并打印出来。
示例代码
package com.tutorialspoint;
import java.awt.Image;
import java.awt.image.BaseMultiResolutionImage;
import java.awt.image.MultiResolutionImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
public class Tester {
public static void main(String[] args) throws IOException, MalformedURLException {
List<String> imgUrls = List.of("http://www.tutorialspoint.com/java9/images/logo.png",
"http://www.tutorialspoint.com/java9/images/mini_logo.png",
"http://www.tutorialspoint.com/java9/images/large_logo.png");
List<Image> images = new ArrayList<Image>();
for (String url : imgUrls) {
images.add(ImageIO.read(new URL(url)));
}
MultiResolutionImage multiResolutionImage =
new BaseMultiResolutionImage(images.toArray(new Image[0]));
List<Image> variants = multiResolutionImage.getResolutionVariants();
System.out.println("Total number of images: " + variants.size());
for (Image img : variants) {
System.out.println(img);
}
}
}
输出
Total number of images: 3
BufferedImage@7ce6a65d: type = 6 ColorModel:
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency = 3
has alpha = true isAlphaPre = false ByteInterleavedRaster: width =311
height = 89
BufferedImage@4c762604: type = 6 ColorModel:
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency = 3
has alpha = true isAlphaPre = false ByteInterleavedRaster: width =156
height = 45
BufferedImage@2641e737: type = 6 ColorModel:
color space =java.awt.color.ICC_ColorSpace@548ad73b transparency = 3
has alpha = true isAlphaPre = false ByteInterleavedRaster: width =622
height = 178
示例 - 获取特定变体
在这个例子中，我们加载了三个图像并将它们存储在 MultiResolutionImage 中。然后使用 getResolutionVariant() 方法根据提供的分辨率获取此多分辨率图像中的特定图像变体并打印出来。如果分辨率没有精确匹配，此方法将返回最近的分辨率图像。
示例代码
package com.tutorialspoint;
import java.awt.Image;
import java.awt.image.BaseMultiResolutionImage;
import java.awt.image.MultiResolutionImage;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
public class Tester {
public static void main(String[] args) throws IOException, MalformedURLException {
List<String> imgUrls = List.of("http://www.tutorialspoint.com/java9/images/logo.png",
"http://www.tutorialspoint.com/java9/images/mini_logo.png",
"http://www.tutorialspoint.com/java9/images/large_logo.png");
List<Image> images = new ArrayList<Image>();
for (String url : imgUrls) {
images.add(ImageIO.read(new URL(url)));
}
MultiResolutionImage multiResolutionImage =
new BaseMultiResolutionImage(images.toArray(new Image[0]));
List<Image> variants = multiResolutionImage.getResolutionVariants();
System.out.println("Total number of images: " + variants.size());
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));
}
}
输出
Total number of images: 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]