数据 URI - 如何在 Java 中创建它们？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/14996746/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Data URI - how to create them in Java?
提问by Khizar
I have just been told to send the thumbnail of an image using data URI. I have been searching it but all I found was that its basically a textual representation of a file and can be directly used in HTML. I could not really find how to make a data URI in Java. I have an input stream of a file. Can someone please shed some light on it and point me to a way to generate this?
我刚刚被告知使用数据 URI 发送图像的缩略图。我一直在搜索它，但我发现它基本上是一个文件的文本表示，可以直接在 HTML 中使用。我真的找不到如何在 Java 中创建数据 URI。我有一个文件的输入流。有人可以对此有所了解并指出一种方法来生成它吗？
回答by Andrew Thompson
E.G. for an image:
图像的 EG：
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
ImageIO.write(image, "png", baos);
} catch (IOException e) {
e.printStackTrace();
}
String imageString = "data:image/png;base64," +
DatatypeConverter.printBase64Binary(baos.toByteArray());
Example
例子
Run the code below. If FF is the default browser, you might see something like this:
运行下面的代码。如果 FF 是默认浏览器，您可能会看到如下内容：
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.xml.bind.DatatypeConverter;
import javax.imageio.ImageIO;
import java.io.ByteArrayOutputStream;
import java.io.*;
public class DataUriConverter {
public static void main(String[] args) throws Exception {
int sz = 200;
BufferedImage image = new BufferedImage(
sz, sz, BufferedImage.TYPE_INT_ARGB);
// paint the image..
Graphics2D g = image.createGraphics();
g.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(Color.BLUE);
for (int ii = 0; ii < sz; ii += 5) {
g.drawOval(ii, ii, sz - ii, sz - ii);
}
g.dispose();
// convert the image
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(image, "png", baos);
System.out.println("baos.toByteArray() " + baos.toByteArray());
System.out.println("baos.toByteArray().length " + baos.toByteArray().length);
String data = DatatypeConverter.printBase64Binary(baos.toByteArray());
String imageString = "data:image/png;base64," + data;
String html =
"<html><body><img src='" + imageString + "'></body></html>";
// write the HTML
File f = new File("image.html");
FileWriter fw = new FileWriter(f);
fw.write(html);
fw.flush();
fw.close();
// display the HTML
Desktop.getDesktop().open(f);
}
}
回答by riversun
Here is my example.
这是我的例子。
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import javax.xml.bind.DatatypeConverter;
public class ToDataURI {
public static void main(String[] args) throws IOException {
// source file
File file = new File("movie.mp4");
// check content type of the file
String contentType = Files.probeContentType(file.toPath());
// read data as byte[]
byte[] data = Files.readAllBytes(file.toPath());
// convert byte[] to base64(java7)
String base64str = DatatypeConverter.printBase64Binary(data);
// convert byte[] to base64(java8)
// String base64str = Base64.getEncoder().encodeToString(data);
// cretate "data URI"
StringBuilder sb = new StringBuilder();
sb.append("data:");
sb.append(contentType);
sb.append(";base64,");
sb.append(base64str);
System.out.println(sb.toString());
}
}
Processing flow
加工流程
- Check file contentType
- Read file data into byte[]
- Convert byte[] data to base64
- Create "data URI" format
- 检查文件内容类型
- 将文件数据读入字节[]
- 将 byte[] 数据转换为 base64
- 创建“数据URI”格式
You can get like
你可以像
data:video/mp4;base64,AAAAIGZ0eXBpc29tAAACAGlzb21p....
