子列表索引超出范围的异常 [英] sublist index out of bound exception

问题描述

每当我运行我的xhtml时。它给了我以下例外。
statusindex对象的值是5.我使用JQuery进行延迟滚动，所以当我的xhml页面
getMoreStatusList调用getMoreStatusList函数时，它会给我一个索引超出范围的异常。
数据库中有26个状态更新，因此索引超出范围的异常对我没有意义。

Whenever I am running my xhtml. It is giving me the following exception. The value of statusindex object is 5. I am using JQuery for lazy scrolling,so when my xhml page getMoreStatusList calls getMoreStatusList function, it is giving me an index out of bound exception. There are 26 status updates in the database so index out of bound exception makes no sense to me.

1）代码

public List<Status> getMoreStatusList() {

    FacesContext context = FacesContext.getCurrentInstance();
    HttpSession session = (HttpSession) context.getExternalContext()
            .getSession(false);
    User user = (User) session.getAttribute("userdet");
    Query query = em.createQuery("SELECT s FROM Status s WHERE s.email='"
            + user.getEmail() + "' ORDER BY s.timeMillis desc",
            Status.class);
    List<Status> results = query.getResultList();
    Query query1 = em.createQuery("SELECT f FROM Friend f WHERE f.email='"
            + user.getEmail() + "'", Friend.class);
    List<Friend> results1 = query1.getResultList();
    Iterator<Friend> it = results1.listIterator();
    while (it.hasNext()) {
        String email = it.next().getFriendEmail();
        Query query2 = em.createQuery(
                "SELECT s FROM Status s WHERE s.email='" + email
                        + "' ORDER BY s.timeMillis desc", Status.class);
        List<Status> results2 = query2.getResultList();
        results.addAll(results2);

    }
    Collections.sort(results);
    int index = (int) session.getAttribute("statusindex");
    System.out.println(index);
    results = results.subList(index,index+5);
    session.setAttribute("statusindex", index + 5);
    return results;

}

2）异常

Mar 02, 2013 9:31:58 PM org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [Faces Servlet] in context with path [/FreeBird_v.6] threw exception [/getMoreStatusList.xhtml @120,43 test="#{p.videostatus!=null}" /getMoreStatusList.xhtml @120,43 test="#{p.videostatus!=null}": /getMoreStatusList.xhtml @14,60 items="#{statusBean.moreStatusList}": Error reading 'moreStatusList' on type com.bean.StatusBean] with root cause
java.lang.IndexOutOfBoundsException: toIndex = 30
    at java.util.SubList.<init>(Unknown Source)
    at java.util.RandomAccessSubList.<init>(Unknown Source)
    at java.util.AbstractList.subList(Unknown Source)
    at java.util.Vector.subList(Unknown Source)
    at com.bean.StatusBean.getMoreStatusList(StatusBean.java:190)
    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 javax.el.BeanELResolver.getValue(BeanELResolver.java:87)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:71)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:169)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:106)
    at com.sun.faces.facelets.tag.jstl.core.IndexedValueExpression.getValue(IndexedValueExpression.java:89)
    at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:68)
    at org.apache.el.parser.AstValue.getValue(AstValue.java:147)
    at org.apache.el.parser.AstNotEqual.getValue(AstNotEqual.java:38)
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189)
    at com.sun.faces.facelets.el.TagValueExpression.getValue(TagValueExpression.java:106)
    at com.sun.faces.facelets.tag.TagAttributeImpl.getObject(TagAttributeImpl.java:326)
    at com.sun.faces.facelets.tag.TagAttributeImpl.getBoolean(TagAttributeImpl.java:133)
    at com.sun.faces.facelets.tag.jstl.core.IfHandler.apply(IfHandler.java:88)
    at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:94)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:131)
    at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:162)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:114)
    at com.sun.faces.facelets.tag.jstl.core.ForEachHandler.apply(ForEachHandler.java:214)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.applyNextHandler(DelegatingMetaTagHandler.java:131)
    at com.sun.faces.facelets.tag.jsf.ComponentTagHandlerDelegateImpl.apply(ComponentTagHandlerDelegateImpl.java:162)
    at javax.faces.view.facelets.DelegatingMetaTagHandler.apply(DelegatingMetaTagHandler.java:114)
    at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:94)
    at com.sun.faces.facelets.compiler.NamespaceHandler.apply(NamespaceHandler.java:89)
    at javax.faces.view.facelets.CompositeFaceletHandler.apply(CompositeFaceletHandler.java:94)
    at com.sun.faces.facelets.compiler.EncodingHandler.apply(EncodingHandler.java:79)
    at com.sun.faces.facelets.impl.DefaultFacelet.apply(DefaultFacelet.java:148)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.buildView(FaceletViewHandlingStrategy.java:734)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:96)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:97)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:135)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:309)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:79)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1001)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:579)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:312)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)

推荐答案

消息说 toIndex 是30.这意味着 statusindex 不是5，正如你所认为的那样，但是：

The message says that toIndex is 30. That means that statusindex is not 5, as you believe it is, but 25:

java.lang.IndexOutOfBoundsException: toIndex = 30

附注，您应该在查询中使用命名参数而不是字符串连接来传递参数。您的代码容易受到SQL注入攻击。如果电子邮件地址恰好包含单引号，它也将失败。

Side note, you should use named parameters in your queries instead of String concatenation to pass parameters. Your code is vulnerable to SQL injection attacks. It will also fail if the email address happens to contain a single quote.

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