项目应用服务器tomcat7,在开发(windows)、测试环境(linux 64bit)均正常。在生产环境(linux 64bit)一直启动不起来,也没有报错。
最终定位问题:执行到bufferedimage.createGraphics();便停止不动了。最终在启动脚本增加
JAVA_OPTS="-Djava.awt.headless=true"解决问题。
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问题解决了,但是至于为什么造成这种问题,还是不是很明白。
参照了http://www.oschina.net/translate/using-headless-mode-in-java-se的文章,依旧是一头雾水。
按照上述文章的介绍,写了一个测试类:
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment(); boolean headless_check = ge.isHeadless(); System.out.println("================java.awt.headless:"+headless_check);
输出结果:在测试环境(linux),抛出异常:
Exception in thread "main" java.lang.InternalError: Can't connect to X11 window server using 'localhost:10.0' as the value of the DISPLAY variable. at sun.awt.X11GraphicsEnvironment.initDisplay(Native Method) at sun.awt.X11GraphicsEnvironment.access$200(X11GraphicsEnvironment.java:65) at sun.awt.X11GraphicsEnvironment$1.run(X11GraphicsEnvironment.java:110) at java.security.AccessController.doPrivileged(Native Method) at sun.awt.X11GraphicsEnvironment.<clinit>(X11GraphicsEnvironment.java:74) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:191) at java.awt.GraphicsEnvironment.createGE(GraphicsEnvironment.java:102) at java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment(GraphicsEnvironment.java:81) at java.awt.image.BufferedImage.createGraphics(BufferedImage.java:1182) at com.tydic.BufferedImageCreateGraphicBug.main(BufferedImageCreateGraphicBug.java:23)
但是在生产环境(linux),打印结果
================java.awt.headless:false
,写一个java类在生产环境(linux)上执行如下代码:
BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); Graphics2D g2 = bi.createGraphics(); g2.setBackground(Color.RED); g2.clearRect(0, 0, width, height); System.getProperty("user.dir"); File f = new File(filename); try { ImageIO.write(bi, formatName , f); } catch (IOException e) { e.printStackTrace(); }
可以正常生成图片!
但是在web应用中,却无法生成图片,且没有抛出异常,一直卡住不动,不知为什么.