javax.swing.JFrame linux x11

Caused by: org.springframework.beans.BeanInstantiationException: Could not instantiate bean class [com.enation.javashop.core.service.impl.HtmlToJpgUtil]: Constructor threw exception; nested exception is java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:115)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:61)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:877)
... 31 more
Caused by: java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:159)
at java.awt.Window.<init>(Window.java:431)
at java.awt.Frame.<init>(Frame.java:403)
at java.awt.Frame.<init>(Frame.java:368)
at javax.swing.JFrame.<init>(JFrame.java:158)
at com.enation.javashop.core.service.impl.HtmlToJpgUtil.<init>(HtmlToJpgUtil.java:18)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:100)
... 33 more