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[英]Error While Uploading in JAVA “message[java.lang.IllegalArgumentException: im == null!]”
[英]java.lang.IllegalArgumentException: im == null! error
我剛剛學會了如何使用線程,我正在嘗試使用線程編碼一些圖像,但我會得到這個錯誤java.lang.IllegalArgumentException:im == null!
我嘗試沒有線程做同樣的事情,它只是慢慢地工作,不是因為圖像io,而是因為編碼圖像所需的時間。 WinDef.HDC是我從JNA庫獲得的變量類型。 當我沒有線程嘗試它時,我可以很容易地寫出1000張圖像(約60mb)。
//The thread class
public class imageEncoderThread extends Thread {
HDC originalImage;
BufferedImage image;
public imageProcessThread (HDC rI) {
originalImage = rI'
}
@Override
public void run() {
//returns a buffered image
image = process(rawImage);
try {
ImageIO.write(image, "jpg", new File (filePath));
} catch (IOException e) {
}
}
}
//full stack trace
Exception in thread "Thread-5" java.lang.IllegalArgumentException: im == null!
at javax.imageio.ImageIO.write(Unknown Source)
at javax.imageio.ImageIO.write(Unknown Source)
at com.capture.SingleImageEncoderThread.run(Thread.java:33)
Exception in thread "Thread-7" java.lang.IllegalArgumentException: im == null!
at javax.imageio.ImageIO.write(Unknown Source)
at javax.imageio.ImageIO.write(Unknown Source)
at com.capture.SingleImageEncoderThread.run(Thread.java:33)
Exception in thread "Thread-6" java.lang.IllegalArgumentException: im == null!
at javax.imageio.ImageIO.write(Unknown Source)
at javax.imageio.ImageIO.write(Unknown Source)
//and so on with the same exception
幾乎可以肯定你不能打電話:
image = JNAScreenShot.encodeRawWindow(rawImage, bounds);
從主ui線程以外的任何線程。 請參閱: http ://social.msdn.microsoft.com/Forums/en-US/vclanguage/thread/6398cda5-5393-4b16-b8dc-5bbf8902033f/(具體來說,我認為HDC不能在主ui線程之外使用) 。
因此,您需要首先創建屏幕截圖,然后將其傳遞給您的線程以執行IO(無論如何,這可能是緩慢的部分)。
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