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。有人可以解释一下并指出一种生成方法吗?
问问题
15342 次
2 回答
21
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," +
Base64.getEncoder().encodeToString(bytes);
例子
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 java.io.*;
import javax.imageio.ImageIO;
import java.util.Base64;
public class DataUriConverter {
static String getImageAsString(BufferedImage image) throws Exception {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
// serialize the image
ImageIO.write(image, "png", baos);
// convert the written image to a byte[]
byte[] bytes = baos.toByteArray();
System.out.println("bytes.length " + bytes.length);
// THIS IS IT! Change the bytes to Base 64 Binary
String data = Base64.getEncoder().encodeToString(bytes);
// add the 'data URI prefix' before returning the image as string
return "data:image/png;base64," + data;
}
static BufferedImage getImage() {
int sz = 500;
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(new Color(0,0,255,63));
g.setStroke(new BasicStroke(1.5f));
for (int ii = 0; ii < sz; ii += 5) {
g.drawOval(ii, ii, sz - ii, sz - ii);
}
g.dispose();
return image;
}
public static void main(String[] args) throws Exception {
String imageString = getImageAsString(getImage());
String htmlFrag = "<html><body><img src='%1s'></body></html>";
String html = String.format(htmlFrag, imageString);
// 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);
}
}
于 2013-02-21T07:33:09.370 回答
2
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());
}
}
加工流程
- 检查文件内容类型
- 将文件数据读入 byte[]
- 将 byte[] 数据转换为 base64
- 创建“数据URI”格式
你可以得到喜欢
data:video/mp4;base64,AAAAIGZ0eXBpc29tAAACAGlzb21p....
于 2017-11-22T05:40:51.467 回答