我有这个托管bean，它对Oracle数据库进行SQL查询，并返回变量SessionTTL，MAXACTIVEUSERS和ACTIVEUSERS的内容。之后，变量内容显示在JSF页面中。
我的问题是这是从SQL查询中获取多个结果的当前方法，以及在加载bean之后使用GetVariablesDB()方法的连接方式是什么。下面的代码将显示空变量，因为未调用方法GetVariablesDB()。
P.S我编辑了代码
import java.io.Serializable;
import javax.enterprise.context.SessionScoped;
// or import javax.faces.bean.SessionScoped;
import javax.inject.Named;
/* include package for SHA-256 encryption */
import java.security.NoSuchAlgorithmException;
/* include SQL Packages */
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import javax.sql.DataSource;
import javax.annotation.Resource;
import javax.faces.context.FacesContext;
import javax.inject.Inject;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;
// or import javax.faces.bean.ManagedBean;
import org.glassfish.osgicdi.OSGiService;
@Named("DashboardController")
@SessionScoped
public class Dashboard implements Serializable {
private String storedPassword = null;
private String stringzoro = null;
private String stringone = null;
private String stringtwo = null;
private String SQL_Statement = null;
public Dashboard() throws SQLException{
GetVariablesDB();
}
/* Call the Oracle JDBC Connection driver */
@Resource(name="jdbc/Oracle")
private DataSource ds;
public String getUser(){
return stringzoro;
}
public String getPassword(){
return stringone;
}
private void GetVariablesDB() throws SQLException {
if (ds == null) throw new SQLException();
Connection conn = ds.getConnection();
if (conn == null) throw new SQLException();
try {
conn.setAutoCommit(false);
boolean committed = false;
try {
SQL_Statement = "SELECT * from GLOBALSETTINGS";
PreparedStatement passwordQuery = conn.prepareStatement(SQL_Statement);
ResultSet result = passwordQuery.executeQuery();
if(result.next()){
stringzoro= result.getString("SessionTTL");
stringone = result.getString("MAXACTIVEUSERS");
stringtwo = result.getString("ACTIVEUSERS");
}
conn.commit();
committed = true;
} finally {
if (!committed) conn.rollback();
}
}
finally {
conn.close();
}
}
}
现在当我尝试执行bean时，我在glassfish中得到了这个错误堆栈：
[#|2012-03-08T18:37:44.233+0200|INFO|glassfish3.1.2|org.glassfish.osgijavaeebase|_ThreadID=3393;_ThreadName=Thread-2;|Deleted /tmp/osgiapp6154116770873802943|#]
[#|2012-03-08T18:37:44.233+0200|INFO|glassfish3.1.2|org.glassfish.osgijavaeebase|_ThreadID=3393;_ThreadName=Thread-2;|Undeployed bundle com.DX_57.SM_57 [275]|#]
[#|2012-03-08T18:37:44.234+0200|INFO|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=3393;_ThreadName=Thread-2;|Stopped com.DX_57.SM_57 [275]|#]
[#|2012-03-08T18:37:44.240+0200|INFO|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=3393;_ThreadName=Thread-2;|Uninstalled com.DX_57.SM_57 [275]|#]
[#|2012-03-08T18:37:44.432+0200|INFO|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=3398;_ThreadName=Thread-2;|com.sun.webui.jsf.component.DropDown::The current value of component propertyForm:deployTable:topActionsGroup1:filter does not match any of the selections.
Did you forget to reset the value after changing the options? |#]
[#|2012-03-08T18:37:54.363+0200|WARNING|glassfish3.1.2|org.apache.catalina.connector.Request|_ThreadID=3942;_ThreadName=Thread-2;|PWC4011: Unable to set request character encoding to UTF-8 from context , because request parameters have already been read, or ServletRequest.getReader() has already been called|#]
[#|2012-03-08T18:37:54.458+0200|INFO|glassfish3.1.2|org.glassfish.admingui|_ThreadID=3942;_ThreadName=Thread-2;|GUI deployment: uploadToTempfile|#]
[#|2012-03-08T18:37:54.459+0200|INFO|glassfish3.1.2|org.glassfish.admingui|_ThreadID=3942;_ThreadName=Thread-2;|uploadFileName=SM_57-1.0-SNAPSHOT.war|#]
[#|2012-03-08T18:37:54.527+0200|INFO|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=68;_ThreadName=Thread-2;|Installed com.DX_57.SM_57 [276] from reference:file:/opt/glassfish3/glassfish/domains/domain1/applications/SM_57-1.0-SNAPSHOT/|#]
[#|2012-03-08T18:37:54.540+0200|INFO|glassfish3.1.2|javax.enterprise.system.std.com.sun.enterprise.server.logging|_ThreadID=68;_ThreadName=Thread-2;|Started com.DX_57.SM_57 [276]|#]
[#|2012-03-08T18:37:54.569+0200|INFO|glassfish3.1.2|javax.enterprise.system.tools.admin.org.glassfish.deployment.admin|_ThreadID=68;_ThreadName=Thread-2;|SM_57-1.0-SNAPSHOT was successfully deployed in 96 milliseconds.|#]
[#|2012-03-08T18:37:54.614+0200|INFO|glassfish3.1.2|org.glassfish.osgijavaeebase|_ThreadID=57;_ThreadName=Thread-2;|Expanded at file:/tmp/osgiapp8052165052141203090/|#]
[#|2012-03-08T18:37:55.059+0200|INFO|glassfish3.1.2|org.glassfish.osgiweb|_ThreadID=57;_ThreadName=Thread-2;|total number of classes with faces annotation = 0|#]
[#|2012-03-08T18:37:55.083+0200|INFO|glassfish3.1.2|javax.enterprise.resource.webcontainer.jsf.config|_ThreadID=57;_ThreadName=Thread-2;|Initializing Mojarra 2.1.6 (SNAPSHOT 20111206) for context '/SM_57-1.0-SNAPSHOT'|#]
[#|2012-03-08T18:37:55.093+0200|INFO|glassfish3.1.2|org.glassfish.osgiweb|_ThreadID=57;_ThreadName=Thread-2;|Faces Config uris excluding the ones named as faces-config.xml = []|#]
[#|2012-03-08T18:37:55.141+0200|INFO|glassfish3.1.2|org.glassfish.osgiweb|_ThreadID=57;_ThreadName=Thread-2;|Facelet Config uris = []|#]
[#|2012-03-08T18:37:55.142+0200|INFO|glassfish3.1.2|javax.enterprise.resource.webcontainer.jsf.config|_ThreadID=57;_ThreadName=Thread-2;|Monitoring jndi:/server/SM_57-1.0-SNAPSHOT/WEB-INF/faces-config.xml for modifications|#]
[#|2012-03-08T18:37:55.165+0200|INFO|glassfish3.1.2|javax.enterprise.system.container.web.com.sun.enterprise.web|_ThreadID=57;_ThreadName=Thread-2;|WEB0671: Loading application [com.DX_57.SM_57_1.0.0.SNAPSHOT] at [/SM_57-1.0-SNAPSHOT]|#]
[#|2012-03-08T18:37:55.183+0200|INFO|glassfish3.1.2|org.glassfish.osgiweb|_ThreadID=57;_ThreadName=Thread-2;|Registered ServletContext as a service with properties: {osgi.web.symbolicname=com.DX_57.SM_57, osgi.web.version=1.0.0.SNAPSHOT, osgi.web.contextpath=/SM_57-1.0-SNAPSHOT} |#]
[#|2012-03-08T18:37:55.186+0200|INFO|glassfish3.1.2|org.glassfish.osgijavaeebase|_ThreadID=57;_ThreadName=Thread-2;|deployed bundle com.DX_57.SM_57 [276] at file:/tmp/osgiapp8052165052141203090/|#]
[#|2012-03-08T18:38:03.560+0200|SEVERE|glassfish3.1.2|javax.enterprise.resource.webcontainer.jsf.application|_ThreadID=322;_ThreadName=Thread-2;|Error Rendering View[/Settings.xhtml]
com.sun.faces.mgbean.ManagedBeanCreationException: Cant instantiate class: com.DX_57.SM_57.Dashboard.
at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:193)
at com.sun.faces.mgbean.BeanBuilder.build(BeanBuilder.java:102)
at com.sun.faces.mgbean.BeanManager.createAndPush(BeanManager.java:409)
at com.sun.faces.mgbean.BeanManager.create(BeanManager.java:269)
at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:244)
at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:116)
at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176)
at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203)
at com.sun.el.parser.AstIdentifier.getValue(AstIdentifier.java:103)
at com.sun.el.parser.AstValue.getValue(AstValue.java:179)
at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:224)
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:109)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UIOutput.getValue(UIOutput.java:169)
at com.sun.faces.renderkit.html_basic.HtmlBasicInputRenderer.getValue(HtmlBasicInputRenderer.java:205)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getCurrentValue(HtmlBasicRenderer.java:355)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeEnd(HtmlBasicRenderer.java:164)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.TableRenderer.renderHeader(TableRenderer.java:337)
at com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:95)
at javax.faces.component.UIComponentBase.encodeBegin(UIComponentBase.java:820)
at javax.faces.component.UIData.encodeBegin(UIData.java:1118)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1755)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1760)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:402)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:131)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
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:594)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1542)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:849)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:746)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1045)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:228)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
Caused by: java.sql.SQLException
at com.DX_57.SM_57.Dashboard.GetVariablesDB(Dashboard.java:70)
at com.DX_57.SM_57.Dashboard.<init>(Dashboard.java:49)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at java.lang.Class.newInstance0(Class.java:372)
at java.lang.Class.newInstance(Class.java:325)
at com.sun.faces.mgbean.BeanBuilder.newBeanInstance(BeanBuilder.java:188)
... 55 more
|#]
这个SQL语句的Java代码是否正确？
答案 0 :(得分：1)
只需在构造函数中调用GetVariablesDB（）即可。为什么你的实例变量和方法是公开的？
如果您在站点启动时需要该数据，那么您应该在构造函数中初始化数据，否则在特定事件中调用public方法。
为了更好的可读性，您应该使用this关键字或至少使用命名约定标记您的实例变量。如果您无法通过名称或访问修饰符来区分变量的范围，则很难遵循代码。