小编kha*_*han的帖子

当我开始寻找多态性的好处时,我在这里找到了这个问题.但在这里我无法找到答案.让我告诉我想找到什么.这里我有一些课程:

class CoolingMachines{
    public void startMachine(){
        //No implementationion
    }
    public void stopMachine(){
        //No implementationion
    }
}

class Refrigerator extends CoolingMachines{
    public void startMachine(){
        System.out.println("Refrigerator Starts");
    }
    public void stopMachine(){
        System.out.println("Refrigerator Stop");
    }
    public void trip(){
        System.out.println("Refrigerator Trip");
    }
}

class AirConditioner extends CoolingMachines{
    public void startMachine(){
        System.out.println("AC Starts");
    }
    public void stopMachine(){
        System.out.println("AC Stop");
    }
}

public class PolymorphismDemo {
    CoolingMachines cm = new Refrigerator();
    Refrigerator rf = new Refrigerator();
}

现在我在Demo类中创建了两个对象,并且是对它的引用Refrigerator.我完全理解从rf对象我可以调用trip()方法 …

大家好,我在创建JAXB解析器时遇到了一个非常奇怪的问题.当我试图从eclipse生成JAXB类时,在一个类中它显示了一个非常奇怪的错误

Access restriction: The type QName is not accessible due to restriction on required library /usr/lib/jvm/jdk1.7.0_02/jre/lib/rt.jar

这是我的班级

package generated;

import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.XmlElementDecl;
import javax.xml.bind.annotation.XmlRegistry;
//import javax.xml.namespace.QName;
import javax.xml.namespace.*;


@XmlRegistry
public class ObjectFactory {

在这条线上,我正在收到错误消息

private final static QName _ExpenseReport_QNAME = new QName("","expenseReport");

    /**
     * Create a new ObjectFactory that can be used to create new instances of schema derived classes for package: generated
     * 
     */
    public ObjectFactory() {
    }

    /**
     * Create an instance of {@link ExpenseT }
     * …

我是HBase和Hadoop的新手.我已经完全设置了HBase并且开始完美.现在,当我尝试使用Java客户端从p1连接到HBase(其中HBase设置在p2上)时,它会抛出一个奇怪的异常.

12/04/17 14:36:37 INFO zookeeper.ZooKeeper: Initiating client connection, connectString=192.168.15.20:2181 sessionTimeout=180000 watcher=hconnection
12/04/17 14:36:38 INFO zookeeper.ClientCnxn: Opening socket connection to server /192.168.15.20:2181
12/04/17 14:36:38 WARN zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing socket connection and attempting reconnect
java.net.ConnectException: Connection refused
    at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
    at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:567)
    at org.apache.zookeeper.ClientCnxn$SendThread.run(ClientCnxn.java:1119)
12/04/17 14:36:39 INFO zookeeper.ClientCnxn: Opening socket connection to server hbase.local/192.168.15.20:2181
12/04/17 14:36:39 WARN zookeeper.ClientCnxn: Session 0x0 for server null, unexpected error, closing socket connection …

@ViewScoped在Spring 3.0中是否有像JSF这样的范围？我有一个使用JSF + Spring的应用程序,其中支持bean由Spring管理.我在Spring中没有找到像JSF wiew作用域这样的范围.我看到博客将JSF 2.0的ViewScope移植到Spring 3.0,但它对我不起作用.

这是我对自定义Spring范围的尝试:

import java.util.Map;

import javax.faces.context.FacesContext;

import org.springframework.beans.factory.ObjectFactory;
import org.springframework.beans.factory.config.Scope;

/**
 * Implements the JSF View Scope for use by Spring. This class is registered as a Spring bean with the CustomScopeConfigurer.
*/
public class ViewScope implements Scope {

    public Object get(String name, ObjectFactory<?> objectFactory) {

        System.out.println("**************************************************");
        System.out.println("-------------------- Getting objects For View Scope ----------");
        System.out.println("**************************************************");
        if (FacesContext.getCurrentInstance().getViewRoot() != null) {
            Map<String, Object> viewMap = FacesContext.getCurrentInstance().getViewRoot().getViewMap();
            if (viewMap.containsKey(name)) {
                return viewMap.get(name);
            } …

在我尝试运行hadoop完成hadoop的设置后,我发现(通过jps)namenode没有运行.我在日志文件中搜索,发现一个例外是"Directory/hadoop/tmp/dfs/name处于不一致状态:存储目录不存在或无法访问"..所以我通过sudo mkdir -p/hadoop/tmp/dfs/name在/ hadoop/tmp/dfs/name中创建了i目录并赋予了这个完整的权限.现在重新启动hadoop后,我发现namenode仍然没有朗姆酒,我发现这个异常"dFSNamesystem initialization failed.java.io.IOException:NameNode没有格式化." 我已经格式化了namenode"{hadoop-dir}/bin hadoop namenode -format"并且格式正常,但namenode日志中的异常仍然存在.这里我的namenode日志如下

2012-04-11 13:19:09,174 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: STARTUP_MSG: 
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG:   host = hbase.com.com/192.168.15.20
STARTUP_MSG:   args = []
STARTUP_MSG:   version = 0.20.205.0
STARTUP_MSG:   build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20-security-205 -r 1179940; compiled by 'hortonfo' on Fri Oct  7 06:20:32 UTC 2011
************************************************************/
2012-04-11 13:19:09,899 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties
2012-04-11 13:19:09,959 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source MetricsSystem,sub=Stats registered.
2012-04-11 13:19:09,965 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s).
2012-04-11 13:19:09,965 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode …

我是HBase的新手,但我已经设置并获得了一些关于HBase和Hadoop的知识.

当我研究HBase MemStore时,我对MemStore的理解是"MemStore是HBase放置必须写入或读取的数据的内存位置".所以,这就是为什么我们想要阅读有关memstore的时间和地点,我们也会看到有关垃圾收集的讨论.

现在我的问题是,memstore的唯一目的是在内存中保存可读和可写数据吗？我们可以调整内存的大小以获得hbase的快速回复吗？垃圾收集配置(收集器配置)会影响memstore吗？我认为应该是的.:)

大家好,我想知道在使用perf4j时logback.xml的确切配置设置.我在logback.xml中创建此配置

<configuration>
    <!-- Perf4J appenders -->
    <!--
       This AsyncCoalescingStatisticsAppender groups StopWatch log messages
       into GroupedTimingStatistics messages which it sends on the
       file appender defined below
    -->
    <appender name="CoalescingStatistics" class="org.perf4j.logback.AsyncCoalescingStatisticsAppender">
        <param name="TimeSlice" value="60000"/>
        <appender-ref ref="graphExecutionTimes"/>
        <appender-ref ref="graphExecutionTPS"/>
        <!-- We add the JMX Appender reference onto the CoalescingStatistics -->
        <appender-ref ref="perf4jJmxAppender"/>
    </appender>

    <appender name="graphExecutionTimes" class="org.perf4j.logback.GraphingStatisticsAppender">
        <!-- Possible GraphTypes are Mean, Min, Max, StdDev, Count and TPS -->
        <param name="GraphType" value="Mean"/>
        <!-- The tags of the timed execution blocks to graph are specified …

我是primeface的新手.当我使用PieChartModel时,它以百分比显示数据.
例如,我的数据是labors = 4,administrator = 6.它将显示一个饼图,显示60%,40%而我希望它在图表上显示6和4.
我们可以这样做吗？

我是JSF的新手,我正在构建一个使用facelets创建的应用程序.
这是我的模板
master.xhtml

<body id="body">
 <form id="frmmaster">
        <div id="pg-nav-bg">
            <div class="wrapper clear">
                <div class="footer clear">
                    <div class="footerContent">Help Des</div>
                </div>
                <div id="pg-nav">
                    <ul class="nav sf-js-enabled">
                        <li class="page_item" id="liHomr">
                            <a href="#" title="Home">Home</a>
                        </li>
                        <li class="page_item" id="liFreeSearch">
                            <a href="#" title="Free Search" >Free Search</a>  
                        </li>
                        <li class="page_item" id="liMasterSearch">      
                            <a href="#"  title="Search">Search</a> 
                        </li>
                        <li class="page_item" id="liAdvanceSearch">
                            <a href="#" title="Advanced Search">Advanced Search</a> 
                        </li>
                        <li class="page_item" id="liCharts">
                            <a href="#" title="Charts" >Charts</a>  <!-- 
                        </li>
                    </ul>
                </div>
            </div>
        </div>
        <div class="wrapper clear">
            <div class="Welcome ">
                <div class="welcome">
                     Welcome! &nbsp;<strong>Searcher</strong> …