在webapp中使用JExcel Api时，Tomcat 7在启动时崩溃
我正在尝试使用JExcel Api在一个特定的servlet被调用时将数据从一个数据库导出到一个Excelsheet中，但是当启动Tomcat时，我得到了多个exception。 这是eclipse给出的错误信息：
Nov 01, 2012 10:57:14 AM org.apache.catalina.core.ContainerBase startInternal SEVERE: A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/web]] at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source) at java.util.concurrent.FutureTask.get(Unknown Source) at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123) at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:785) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/web]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) ... 7 more Caused by: java.lang.NoClassDefFoundError: jxl/write/WriteException at java.lang.Class.getDeclaredFields0(Native Method) at java.lang.Class.privateGetDeclaredFields(Unknown Source) at java.lang.Class.getDeclaredFields(Unknown Source) at org.apache.catalina.util.Introspection.getDeclaredFields(Introspection.java:87) at org.apache.catalina.startup.WebAnnotationSet.loadFieldsAnnotation(WebAnnotationSet.java:261) at org.apache.catalina.startup.WebAnnotationSet.loadApplicationServletAnnotations(WebAnnotationSet.java:140) at org.apache.catalina.startup.WebAnnotationSet.loadApplicationAnnotations(WebAnnotationSet.java:67) at org.apache.catalina.startup.ContextConfig.applicationAnnotationsConfig(ContextConfig.java:405) at org.apache.catalina.startup.ContextConfig.configureStart(ContextConfig.java:881) at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:369) at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:119) at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90) at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5173) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ... 7 more Caused by: java.lang.ClassNotFoundException: jxl.write.WriteException at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1714) at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1559) ... 21 more Nov 01, 2012 10:57:14 AM org.apache.catalina.core.ContainerBase startInternal SEVERE: A child container failed during start java.util.concurrent.ExecutionException: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]] at java.util.concurrent.FutureTask$Sync.innerGet(Unknown Source) at java.util.concurrent.FutureTask.get(Unknown Source) at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1123) at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) at org.apache.catalina.startup.Catalina.start(Catalina.java:684) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:451) Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559) at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549) at java.util.concurrent.FutureTask$Sync.innerRun(Unknown Source) at java.util.concurrent.FutureTask.run(Unknown Source) at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: org.apache.catalina.LifecycleException: A child container failed during start at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131) at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:785) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ... 7 more Nov 01, 2012 10:57:14 AM org.apache.catalina.startup.Catalina start SEVERE: Catalina.start: org.apache.catalina.LifecycleException: Failed to start component [StandardServer[8005]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) at org.apache.catalina.startup.Catalina.start(Catalina.java:684) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:322) at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:451) Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardService[Catalina]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:732) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ... 7 more Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina]] at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:154) at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ... 9 more Caused by: org.apache.catalina.LifecycleException: A child container failed during start at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1131) at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:302) at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150) ... 11 more 这是servlet代码：
import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import jxl.write.WriteException; /** * Servlet implementation class Test */ @WebServlet(description = "A simple test.", urlPatterns = { "/test" }) public class Test extends HttpServlet { private static final long serialVersionUID = 1L; /** * @see HttpServlet#HttpServlet() */ public Test() { super(); } /** * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response) */ protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { try { WriteExcel.writeTestFile(); } catch (WriteException e) { e.printStackTrace(); } response.setContentType("text/html"); PrintWriter out = response.getWriter(); out.println("<html>"); out.println("<head>"); out.println("<title>Test!</title>"); out.println("</head>"); out.println("<body>"); out.println("I've written an Excel file!"); out.println("</body>"); out.println("</html>"); } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
这里是WriteExcel类的代码：
import java.io.File; import java.io.IOException; import java.util.Locale; import jxl.CellView; import jxl.Workbook; import jxl.WorkbookSettings; import jxl.format.UnderlineStyle; import jxl.write.Formula; import jxl.write.Label; import jxl.write.Number; import jxl.write.WritableCellFormat; import jxl.write.WritableFont; import jxl.write.WritableSheet; import jxl.write.WritableWorkbook; import jxl.write.WriteException; import jxl.write.biff.RowsExceededException; //tomcat hat probleme mit der jxl library public class WriteExcel { private WritableCellFormat timesBoldUnderline; private WritableCellFormat times; private String inputFile; public void setOutputFile(String inputFile) { this.inputFile = inputFile; } public void write() throws IOException, WriteException { File file = new File(inputFile); WorkbookSettings wbSettings = new WorkbookSettings(); wbSettings.setLocale(new Locale("en", "EN")); WritableWorkbook workbook = Workbook.createWorkbook(file, wbSettings); workbook.createSheet("Report", 0); WritableSheet excelSheet = workbook.getSheet(0); createLabel(excelSheet); createContent(excelSheet); workbook.write(); workbook.close(); } private void createLabel(WritableSheet sheet) throws WriteException { // Lets create a times font WritableFont times10pt = new WritableFont(WritableFont.TIMES, 10); // Define the cell format times = new WritableCellFormat(times10pt); // Lets automatically wrap the cells times.setWrap(true); // Create create a bold font with unterlines WritableFont times10ptBoldUnderline = new WritableFont(WritableFont.TIMES, 10, WritableFont.BOLD, false, UnderlineStyle.SINGLE); timesBoldUnderline = new WritableCellFormat(times10ptBoldUnderline); // Lets automatically wrap the cells timesBoldUnderline.setWrap(true); CellView cv = new CellView(); cv.setFormat(times); cv.setFormat(timesBoldUnderline); cv.setAutosize(true); // Write a few headers addCaption(sheet, 0, 0, "Header 1"); addCaption(sheet, 1, 0, "This is another header"); } private void createContent(WritableSheet sheet) throws WriteException, RowsExceededException { // Write a few number for (int i = 1; i < 10; i++) { // First column addNumber(sheet, 0, i, i + 10); // Second column addNumber(sheet, 1, i, i * i); } // Lets calculate the sum of it StringBuffer buf = new StringBuffer(); buf.append("SUM(A2:A10)"); Formula f = new Formula(0, 10, buf.toString()); sheet.addCell(f); buf = new StringBuffer(); buf.append("SUM(B2:B10)"); f = new Formula(1, 10, buf.toString()); sheet.addCell(f); // Now a bit of text for (int i = 12; i < 20; i++) { // First column addLabel(sheet, 0, i, "Boring text " + i); // Second column addLabel(sheet, 1, i, "Another text"); } } private void addCaption(WritableSheet sheet, int column, int row, String s) throws RowsExceededException, WriteException { Label label; label = new Label(column, row, s, timesBoldUnderline); sheet.addCell(label); } private void addNumber(WritableSheet sheet, int column, int row, Integer integer) throws WriteException, RowsExceededException { Number number; number = new Number(column, row, integer, times); sheet.addCell(number); } private void addLabel(WritableSheet sheet, int column, int row, String s) throws WriteException, RowsExceededException { Label label; label = new Label(column, row, s, times); sheet.addCell(label); } public static void writeTestFile() throws WriteException, IOException { WriteExcel test = new WriteExcel(); test.setOutputFile("d:/test.xls"); test.write(); System.out.println("Please check the result file under d:/test.xls"); } }
WriteExcel类的writeTestFile（）方法在本地独立项目中testing时工作正常。
当方法writeTestFile（）不被调用时，servlet本身也可以工作。
有人能澄清我为什么得到例外吗？
还有一个修复或解决方法？
试试这个：双击服务器，点击“打开启动configuration”，进入Classpath选项卡，在User Entries下添加jar。