java - 将随机字符串图像写入资源

Question

我想生成一个随机字符串，然后需要将其转换为图像。我想将此图像存储在我的 spring 资源文件夹中。

@Service
public class CapchaServiceImpl implements CapchaService{

@Override
public void CapchaString() {
    String capchaString = UUID.randomUUID().toString();
ByteArrayInputStream bais = new ByteArrayInputStream(capchaString.getBytes());
           try {
              BufferedImage bi=ImageIO.read(bais);
              File outputfile = new File("/resources/saved.png");
              ImageIO.write(bi, "png", outputfile);

          } catch (IOException e) {
              throw new RuntimeException(e);
          }
      }

}

但是，当我使用这个时，我得到了 java.lang.IllegalArgumentException: image == null!异常(exception)。为什么以及我需要做什么？

Answer 1

试试这个

    public static void main(String args[])
    {

         String capchaString = UUID.randomUUID().toString();
//       ByteArrayInputStream bais = new ByteArrayInputStream(capchaString.getBytes());
                    try {
                       BufferedImage bi=new BufferedImage(100, 100, BufferedImage.TYPE_INT_RGB);
                       Graphics g = bi.getGraphics();
                       g.drawString(capchaString, 10, 10);

                       File outputfile = new File("output.png");
                       ImageIO.write(bi, "png", outputfile);

                   } catch (IOException e) {
                       throw new RuntimeException(e);
                   }


    }