就會報以下的錯誤，是由於cell styles太多create造成，故一般可以把cellstyle設置放到循環外面
報錯如下：
Caused by: java.lang.IllegalStateException: The maximum number of cell styles was exceeded. You can define up to 4000 styles in a .xls workbook
at org.apache.poi.hssf.usermodel.HSSFWorkbook.createCellStyle(HSSFWorkbook.java:1144)
at org.apache.poi.hssf.usermodel.HSSFWorkbook.createCellStyle(HSSFWorkbook.java:88)
at com.trendmicro.util.toExcel.ExcelExporter.addWorkbook(ExcelExporter.java:612)
at com.trendmicro.util.toExcel.ExcelExporter.exportToExcel(ExcelExporter.java:112)
at com.trendmicro.util.toExcel.ReportExporter.exportAutomationReport(ReportExporter.java:190)
at com.trendmicro.view.reports.TestCaseAutomationBean.exportAutoReport(TestCaseAutomationBean.java:856)
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:597)
at org.apache.el.parser.AstValue.invoke(AstValue.java:191)
at org.apache.el.MethodExpressionImpl.invoke(MethodExpressionImpl.java:276)
at org.apache.jasper.el.JspMethodExpression.invoke(JspMethodExpression.java:68)
at javax.faces.component.MethodBindingMethodExpressionAdapter.invoke(MethodBindingMethodExpressionAdapter.java:88)
... 33 more
