【发布时间】：2012-09-15 22:01:14
【问题描述】：
每当我从 xhtml 页面调用 getFriendList 函数时，我都会遇到异常。该页面继续加载，然后我停止浏览器。我得到了给定的堆栈跟踪。它告诉我第 78 行 friends.add(friend); 有错误。我认为我的语法有问题。如果有人指出错误会很有帮助。
1)这是我的 FriendBean，它是请求范围的。
package com.bean;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import javax.faces.context.FacesContext;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
import javax.servlet.http.HttpSession;
import com.entity.Friend;
import com.entity.User;
public class FriendBean {
Friend friend;
private EntityManager em;
public FriendBean(){
friend = new Friend();
EntityManagerFactory emf=Persistence.createEntityManagerFactory("FreeBird");
em =emf.createEntityManager();
}
public Friend getFriend() {
return friend;
}
public void setFriend(Friend friend) {
this.friend = friend;
}
public List<Friend> getFriendRequestList(){
FacesContext context = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession) context.getExternalContext().getSession(true);
User user=(User) session.getAttribute("userdet");
Query query = em.createQuery("SELECT f FROM Friend f WHERE f.email='"+user.getEmail()+"' AND f.status=0",Friend.class);
List<Friend> results =query.getResultList();
return results;
}
public String friendAccept(String friendRequestId){
System.out.println("friend accept called...");
Friend f=em.find(Friend.class,Integer.parseInt(friendRequestId));
f.setStatus(1);
em.getTransaction().begin();
em.persist(f);
em.getTransaction().commit();
Friend viceversa=new Friend();
viceversa.setEmail(f.getFriendEmail());
viceversa.setFriendEmail(f.getEmail());
viceversa.setStatus(1);
em.getTransaction().begin();
em.persist(viceversa);
em.getTransaction().commit();
return "success";
}
public String friendReject(String friendRequestId){
System.out.println("friend reject called..");
Friend f = em.find(Friend.class,Integer.parseInt(friendRequestId));
em.getTransaction().begin();
em.remove(f);
em.getTransaction().commit();
return "success";
}
public List<User> getFriendList(){
FacesContext context = FacesContext.getCurrentInstance();
HttpSession session = (HttpSession) context.getExternalContext().getSession(true);
User user=(User) session.getAttribute("userdet");
Query query = em.createQuery("SELECT f FROM Friend f WHERE f.email='"+user.getEmail()+"' AND f.status=1",Friend.class);
List<Friend> results =query.getResultList();
ArrayList<User> friends = new ArrayList<User>();
while(results.listIterator().hasNext()){
User friend =em.find(User.class,results.listIterator().next().getFriendEmail());
friends.add(friend);
}
return friends;
}
}
2）这是我得到的例外。
SEVERE: Error Rendering View[/Home.xhtml]
javax.el.ELException: /Home.xhtml @146,59 value="#{friendBean.friendList}": java.lang.OutOfMemoryError: Java heap space
at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:114)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:194)
at javax.faces.component.ComponentStateHelper.eval(ComponentStateHelper.java:182)
at javax.faces.component.UIData.getValue(UIData.java:731)
at javax.faces.component.UIData.getDataModel(UIData.java:1798)
at javax.faces.component.UIData.setRowIndexWithoutRowStatePreserved(UIData.java:484)
at javax.faces.component.UIData.setRowIndex(UIData.java:473)
at com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:81)
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 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:1550)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:343)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:256)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:217)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:279)
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$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$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.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2245)
at java.util.Arrays.copyOf(Arrays.java:2219)
at java.util.ArrayList.grow(ArrayList.java:213)
at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:187)
at java.util.ArrayList.add(ArrayList.java:411)
at com.bean.FriendBean.getFriendList(FriendBean.java:78)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:363)
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.AstValue.getValue(AstValue.java:138)
at com.sun.el.parser.AstValue.getValue(AstValue.java:183)
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.UIData.getValue(UIData.java:731)
at javax.faces.component.UIData.getDataModel(UIData.java:1798)
at javax.faces.component.UIData.setRowIndexWithoutRowStatePreserved(UIData.java:484)
at javax.faces.component.UIData.setRowIndex(UIData.java:473)
at com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:81)
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 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)
WARNING: StandardWrapperValve[Faces Servlet]: PWC1406: Servlet.service() for servlet Faces Servlet threw exception
java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2245)
at java.util.Arrays.copyOf(Arrays.java:2219)
at java.util.ArrayList.grow(ArrayList.java:213)
at java.util.ArrayList.ensureCapacityInternal(ArrayList.java:187)
at java.util.ArrayList.add(ArrayList.java:411)
at com.bean.FriendBean.getFriendList(FriendBean.java:78)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at javax.el.BeanELResolver.getValue(BeanELResolver.java:363)
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.AstValue.getValue(AstValue.java:138)
at com.sun.el.parser.AstValue.getValue(AstValue.java:183)
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.UIData.getValue(UIData.java:731)
at javax.faces.component.UIData.getDataModel(UIData.java:1798)
at javax.faces.component.UIData.setRowIndexWithoutRowStatePreserved(UIData.java:484)
at javax.faces.component.UIData.setRowIndex(UIData.java:473)
at com.sun.faces.renderkit.html_basic.TableRenderer.encodeBegin(TableRenderer.java:81)
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 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)
【问题讨论】：
-
您的 SQL 语句正在打开您的应用程序以进行 SQL 注入... tsk tsk tsk .. :) 您最好使用 PreparedStatement 并向其添加参数。在这里查看如何做到这一点：docs.oracle.com/javase/tutorial/jdbc/basics/prepared.html 还有一些关于 SQL 注入的背景知识：owasp.org/index.php/Preventing_SQL_Injection_in_Java
-
@DomenicD。我正要写它:)，好点。另一件事是这一行：
HttpSession session = (HttpSession) context.getExternalContext().getSession(true);表示：如果 session 不存在，则 create new。我想这不是你想要的。所以请改用getSession(false)- 如果存在 session 则获取它，否则不要创建新的并获取null。