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我使用了Google搜索，但找不到解決方案。它來自Core JSF 3rd。'＃{customer.all}'讀取帶有根本原因的類型爲com.corejsf.CustomerBean的'all'時出錯java.lang.NullPointerException
我所做的：
1）包括JSF鑽嘴魚科在構建路徑。
2）包含在生成路徑中的MySQL JDBC驅動程序。
3）將MySQL JDBC驅動程序複製到Tomcat「lib」文件夾和「ext」JDK文件夾中。
4）我用小型Java應用測試了JDBC驅動程序併成功。
CustomerBean從corejsf源代碼：
public class CustomerBean {
@Resource(name="jdbc/corejsf")
private DataSource source;
public ResultSet getAll() throws SQLException {
Connection conn = source.getConnection();
try {
Statement stmt = conn.createStatement();
ResultSet result = stmt.executeQuery("SELECT * FROM Customers");
// return ResultSupport.toResult(result);
CachedRowSet crs = new com.sun.rowset.CachedRowSetImpl();
// or use an implementation from your database vendor
crs.populate(result);
return crs;
} finally {
conn.close();
}
}
}
錯誤：
SEVERE: Servlet.service() for servlet [Faces Servlet] in context with path [/DatabaseTest] threw exception [/index.jsp(12,3) '#{customer.all}' Error reading 'all' on type com.corejsf.CustomerBean] with root cause
java.lang.NullPointerException
at com.corejsf.CustomerBean.getAll(CustomerBean.java:18)
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 javax.el.BeanELResolver.getValue(BeanELResolver.java:87)
at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:72)
at org.apache.el.parser.AstValue.getValue(AstValue.java:169)
at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
at org.apache.jasper.el.JspValueExpression.getValue(JspValueExpression.java:106)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:190)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:178)
at javax.faces.component.UIData.getValue(UIData.java:554)
at javax.faces.component.UIData.getDataModel(UIData.java:1248)
at javax.faces.component.UIData.setRowIndex(UIData.java:447)
at com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:81)
at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:823)
at javax.faces.component.UIData.encodeBegin(UIData.java:937)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1611)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:848)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1613)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1616)
at com.sun.faces.application.view.JspViewHandlingStrategy.doRenderView(JspViewHandlingStrategy.java:420)
at com.sun.faces.application.view.JspViewHandlingStrategy.renderView(JspViewHandlingStrategy.java:209)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:126)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:127)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:313)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:317)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:204)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:182)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:311)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
從'CustomerBean.java：18'拋出異常。你的列表中有哪一行？ – meriton 2011-05-28 12:21:58
Connection conn = source.getConnection（）; – Emerald214 2011-05-28 12:23:54