从Java InputStream打开图像文件

Question

我正在尝试使用计算机上的默认图像查看器打开打包在.jar文件中的图像文件。

我找到了很多关于如何使用InputStream访问打包在jar中的文件的答案，但是如何使用该InputStream打开这些文件呢？

InputStream imageStream = Test.class.getClass().getResourceAsStream("/test/DSC_6283.jpg");

我可以将它转换成Image、ImageIcon或BufferedImage，但如何在默认的图像查看器中打开图像呢？

我的类名是'Test'，我正在尝试访问的图像是C:\Users\Pranav\Documents\NetBeansProjects\Test\src\test\DSC_6283.jpg 任何帮助都将不胜感激。

- Pranav

Answer 1

纯Java：

public static void main(String... args) throws IOException {
    InputStream imageStream = Test.class.getClass().getResourceAsStream("/test/DSC_6283.jpg");
    Path path = Files.createTempFile("DSC_6283", ".jpg");
    try (FileOutputStream out = new FileOutputStream(path.toFile())) {
        byte[] buffer = new byte[1024]; 
        int len; 
        while ((len = imageStream.read(buffer)) != -1) { 
            out.write(buffer, 0, len); 
        }
    } catch (Exception e) {
        // TODO: handle exception
    }
    Desktop.getDesktop().open(path.toFile());
}

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Edit:

        byte[] buffer = new byte[1024]; //allocate an array of bytes to use as a buffer. 1024 bytes in this case
        int len; //a variable to record the number of bytes actually read from the stream each loop
        while ((len = imageStream.read(buffer)) != -1) { //InputStream.read(byte[]) reads bytes from the stream and places them into the buffer. It returns the number of bytes placed into the buffer, or -1 if there is nothing more to read. We store that result in len, and evaluate if we should stop looping (ie if the return is -1)
            out.write(buffer, 0, len); //write to the output file, from the buffer, starting at position 0, through the number of bytes read

注意，这是样板文件。我从Easy way to write contents of a Java InputStream to an OutputStream中盗用了这个版本。

- Andreas

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非常感谢！:) 完美运行！您能否解释一下这些代码的作用-byte[] buffer = new byte[1024];int len; while ((len = imageStream.read(buffer)) != -1) { out.write(buffer, 0, len); } - Pranav

@Pranav 添加了注释 - Andreas

非常感谢！:D @Andreas - Pranav

Answer 2

1. 将图像本地保存（例如 c:\my_image.jpg），而非在 .jar 文件中
2. 使用 Runtime.getRuntime().exec("cmd your_command_here_to_open_image"); 执行命令打开图像，这里有一个关于 Windows 上 cmd 命令的链接: http://www.sevenforums.com/software/180378-where-windows-photo-viewer-default-location.html

- russu

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临时文件夹可能比C:\更合适。 - jtahlborn