我为一个冗长的问题表示歉意,但我真的需要你的帮助。作为我们项目的一部分,我目前正在研究一个搜索引擎,它可以即时更新结果列表:用户键入前4个字符,然后键入结果列表更改。搜索值在文本框中键入,而结果显示在下面的RichData组件rich:Table中。如果搜索值被删除,结果列表为空。然而,在我尝试了几次之后,我得到了组件本身抛出的ConcurrentModificationException。我正在搜索的初始列表来自属性文件(因为我不希望搜索在用户输入内容时触及数据库)。几个月来,我一直在嘲笑它。我错过了什么?让我告诉你我做了什么:使用Richfaces的ConcurrentModificationException扩展数据表
这是应该触发搜索逻辑的输入文本(当数值少于4个字符时,我确保表格不会更新,或者如果用户按下键,似箭,Shift和CTRL - 这个功能是 “returnunicode(事件)”):
<h:inputText id="firmname" value="#{ExtendedTableBean.searchValue}">
<a4j:support reRender="resultsTable" onsubmit="
if ((this.value.length<4 && this.value.length>0) || !returnunicode(event)) {
return false;
}" actionListener="#{ExtendedTableBean.searchForResults}" event="onkeyup" />
</h:inputText>
动作监听器是什么都要更新列表。这里是extendedDataTable,正下方的inputText:
<rich:extendedDataTable tableState="#{ExtendedTableBean.tableState}" var="item"
id="resultsTable" value="#{ExtendedTableBean.dataModel}">
... <%-- I'm listing columns here --%>
</rich:extendedDataTable>
现在,如果它的确定,我想向您展示后端代码。我只留下了对我的问题很重要的逻辑。
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package com.beans;
import java.io.FileInputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.ConcurrentModificationException;
import java.util.List;
import java.util.Properties;
import java.util.concurrent.CopyOnWriteArrayList;
import javax.faces.context.FacesContext;
import javax.faces.event.ActionEvent;
import org.richfaces.model.DataProvider;
import org.richfaces.model.ExtendedTableDataModel;
public class ExtendedTableBean {
private String sortMode="single";
private ExtendedTableDataModel<ResultObject> dataModel;
//ResultObject is a simple pojo and getResultsPerValue is a method that
//read the data from the properties file, assigns it to this pojo, and
//adds a pojo to the list
private Object tableState;
private List<ResultObject> results = new CopyOnWriteArrayList<ResultObject>();
private List<ResultObject> selectedResults =
new CopyOnWriteArrayList<ResultObject>();
private String searchValue;
/**
* This is the action listener that the user triggers, by typing the search value
*/
public void searchForResults(ActionEvent e) {
synchronized(results) {
results.clear();
}
//I don't think it's necessary to clear results list all the time, but here
//I also make sure that we start searching if the value is at least 4
//characters long
if (this.searchValue.length() > 3) {
results.clear();
updateTableList();
} else {
results.clear();
}
dataModel = null; // to force the dataModel to be updated.
}
public List<ResultObject> getResultsPerValue(String searchValue) {
List<ResultObject> resultsList = new CopyOnWriteArrayList<ResultObject>();
//Logic for reading data from the properties file, populating ResultObject
//and adding it to the list
return resultsList;
}
/**
* This method updates a firm list, based on a search value
*/
public void updateTableList() {
try {
List<ResultObject> searchedResults = getResultsPerValue(searchValue);
//Once the results have been retrieved from the properties, empty
//current firm list and replace it with what was found.
synchronized(firms) {
firms.clear();
firms.addAll(searchedFirms);
}
} catch(Throwable xcpt) {
//Exception handling
}
}
/**
* This is a recursive method, that's used to constantly keep updating the
* table list.
*/
public synchronized ExtendedTableDataModel<ResultObject> getDataModel() {
try {
if (dataModel == null) {
dataModel = new ExtendedTableDataModel<ResultObject>(
new DataProvider<ResultObject>() {
public ResultObject getItemByKey(Object key) {
try {
for(ResultObject c : results) {
if (key.equals(getKey(c))){
return c;
}
}
} catch (Exception ex) {
//Exception handling
}
return null;
}
public List<ResultObject> getItemsByRange(
int firstRow, int endRow) {
return Collections.unmodifiableList(results.subList(firstRow, endRow));
}
public Object getKey(ResultObject item) {
return item.getResultName();
}
public int getRowCount() {
return results.size();
}
});
}
} catch (Exception ex) {
//Exception handling
}
return dataModel;
}
//Getters and setters
}
就像我说的,它工作正常,但是当快速的用户类型或删除快(这是很难赶上正好当它发生时),ConcurrentModificationException的异常。这里是什么样子完全相同:
WARNING: executePhase(RENDER_RESPONSE 6,[email protected]) threw exception
java.util.ConcurrentModificationException
at java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at org.richfaces.model.ExtendedTableDataModel.walk(ExtendedTableDataModel.java:108)
at org.ajax4jsf.component.UIDataAdaptorBase.walk(UIDataAdaptorBase.java:1156)
at org.richfaces.renderkit.AbstractExtendedRowsRenderer.encodeRows(AbstractExtendedRowsRenderer.java:159)
at org.richfaces.renderkit.AbstractExtendedRowsRenderer.encodeRows(AbstractExtendedRowsRenderer.java:142)
at org.richfaces.renderkit.AbstractExtendedRowsRenderer.encodeChildren(AbstractExtendedRowsRenderer.java:191)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:812)
at org.ajax4jsf.renderkit.RendererBase.renderChild(RendererBase.java:277)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxComponent(AjaxChildrenRenderer.java:166)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxChildren(AjaxChildrenRenderer.java:83)
at org.ajax4jsf.renderkit.AjaxChildrenRenderer.encodeAjaxComponent(AjaxChildrenRenderer.java:157)
...
的Java代码同步从来就不是我最强的一面,我不知道会是什么引起的错误,最重要的是,我怎么能摆脱它。我知道,Richfaces 4.0已经对rich:extendedDataTable组件做了很多改变,我听说这是一个问题,现在已经解决了。但是,我没有时间将整个应用程序升级到Richfaces 4.0(这将在第2阶段完成),这只是整个项目的一小部分。如果没有办法解决上述问题,那么可能有一种解决方法?或者,也许还有其他方法可以使用普通的JSF来实现类似的搜索(只要它足够快就可以实现)。对于这个问题,我会很感激任何帮助或建议。我希望代码足够容易理解,但如果没有,请告诉我,我会进一步解释。预先感谢您,我非常感谢您的帮助。
谢谢,这正是我需要的。我之前使用过ajaxSingle,只是没有考虑过。然而,EventsQueue对我来说是新的。原来那很简单。再次感谢,这真的有帮助。 – 2012-02-01 08:23:50