如何从InputStream中读取ImageIO：Java

Question

I have created executable jar file(using Eclipse) , there are a set of image (.png) files that is to be inculded in the jar. So I have added a source folder with all the images inside /images folder in the project . Code has to access these file to create BufferedImage using ImageIO.read(new File(path);

Earlier, To get the path I used ClassName.class.getResource(/image/test.png).toURI();

On executing jar , it throw error URI is not hierarchical

So now I am using ClassName.class.getResourceAsStream(/image/test.png);

But how to make ImageIO read from Inputstream ? I tried cast as follows

InputStreamReader resourceBuff=ClassName.class.getResourceAsStream(/image/test.png);
ImageIO.read((ImageInputStream) new InputStreamReader(resourceBuff));

It throws error InputStreamReader cannot be cast to ImageInputStream

Answer 1

ImageIO.read() takes InputStream as a parameter so there is no meaning of casting it to ImageInputStream .

Secondly you can not cast an InputStreamReader object to ImageInputStream because ImageInputStream has nothing to do with InputStreamReader which you thought of.

Moreover getResourceAsStream() returns InputStream . So you can directly do it like this.

InputStream resourceBuff = YourClass.class.getResourceAsStream(filepath);
BufferedImage bf = ImageIO.read(resourceBuff);

Answer 2

The ImageIO class has a utility method to read an InputStream and create a BufferedImage .

There is also a utility method to create an ImageInputStream from an InputStream .