为什么不可以用"提入博客"

情况如下

VelocityViewServlet : Error processing the template
Invocation of method ’log’ in class dlog4j.velocity.ObjectTools threw exception class java.lang.IndexOutOfBoundsException : null

java.lang.IndexOutOfBoundsException
at java.io.FileOutputStream.writeBytes(Native Method)
at java.io.FileOutputStream.write(FileOutputStream.java:260)
at dlog4j.util.WebUtil.getUrlToFile(WebUtil.java:51)
at dlog4j.velocity.ObjectTools.log(ObjectTools.java:911)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:267)
at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:197)
at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:175)
at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:327)
at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:51)
at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:95)
at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:230)
at org.apache.velocity.Template.merge(Template.java:256)
at org.apache.velocity.tools.view.servlet.VelocityViewServlet.mergeTemplate(VelocityViewServlet.java:592)
at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doRequest(VelocityViewServlet.java:417)
at org.apache.velocity.tools.view.servlet.VelocityViewServlet.doGet(VelocityViewServlet.java:373)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:126)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:103)
at com.caucho.server.http.FilterChainServlet.doFilter(FilterChainServlet.java:96)
at com.caucho.server.http.Invocation.service(Invocation.java:315)
at com.caucho.server.http.CacheInvocation.service(CacheInvocation.java:135)
at com.caucho.server.http.RunnerRequest.handleRequest(RunnerRequest.java:344)
at com.caucho.server.http.RunnerRequest.handleConnection(RunnerRequest.java:274)
at com.caucho.server.TcpConnection.run(TcpConnection.java:139)
at java.lang.Thread.run(Thread.java:534)