esper的安装与导入包的使用

1. esper的安装：

在 http://esper.codehaus.org/esper/download/download.html 这里下载esper压缩包。解压缩之后获得文件夹 esper-4.x.x，在该文件夹根目录有 esper-4.x.x.jar，这就是我们需要用到的esper库，将其加入到项目中。值得注意的是，使用esper不仅仅需要这个jar文件，还需要esper所依赖的其他的库。我们还需要将 esper-4.x.x/esper/lib 文件夹内的4个jar文件同样加入项目，这样才能正常使用 esper。

2. 详细安装方法：

已经安装好esper的同学可以直接跳至第三步。由于本人刚刚学习Java，对于Java的对于第三方库的使用非常不了解。所以费了老半天劲才将esper引入项目，其实很简单。(1) 将esper-4.x.x.jar 文件拖入eclipse的项目中，选择“Copy File”。(2) 右击项目名 => Properties => Libraries => Add JARs => 选择 esper-4.x.x.jar => OK ，这样，esper就安装好了。(3) 同样的办法引入 esper-4.x.x/esper/lib 文件夹内的另外4个jar文件。之后，esper就可以使用了。

import com.espertech.esper.client.*; import java.util.Random; import java.util.Date;

public class exampleMain {

public static class Tick {
    String symbol;
    Double price;
    Date timeStamp;

    public Tick(String s, double p, long t) {
        symbol = s;
        price = p;
        timeStamp = new Date(t);
    }
    public double getPrice() {return price;}
    public String getSymbol() {return symbol;}
    public Date getTimeStamp() {return timeStamp;}

    @Override
    public String toString() {
        return "Price: " + price.toString() + " time: " + timeStamp.toString();
    }
}

private static Random generator = new Random();

public static void GenerateRandomTick(EPRuntime cepRT) {

    double price = (double) generator.nextInt(10);
    long timeStamp = System.currentTimeMillis();
    String symbol = "AAPL";
    Tick tick = new Tick(symbol, price, timeStamp);
    System.out.println("Sending tick:" + tick);
    cepRT.sendEvent(tick);

}

public static class CEPListener implements UpdateListener {

    public void update(EventBean[] newData, EventBean[] oldData) {
        System.out.println("Event received: " + newData[0].getUnderlying());
    }
}

public static void main(String[] args) {

//The Configuration is meant only as an initialization-time object.
Configuration cepConfig = new Configuration();
cepConfig.addEventType(“StockTick”, Tick.class.getName());
EPServiceProvider cep = EPServiceProviderManager.getProvider(“myCEPEngine”, cepConfig);
EPRuntime cepRT = cep.getEPRuntime();

    EPAdministrator cepAdm = cep.getEPAdministrator();
    EPStatement cepStatement = cepAdm.createEPL("select * from " +
            "StockTick(symbol='AAPL').win:length(2) " +
            "having avg(price) > 6.0");

    cepStatement.addListener(new CEPListener());

   // We generate a few ticks...
    for (int i = 0; i < 5; i++) {
        GenerateRandomTick(cepRT);
    }
}

}`
输出：

 
 

   
   

    
    

   
   
   
   

    
    

     
     log4j:
     
     WARN No appenders could be found for logger (com.espertech.esper.epl.metric.MetricReportingPath).
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     log4j:WARN Please initialize the log4j system properly.
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     Sending tick:Price: 6.0 time: Tue Jul 21 01:11:15 CEST 2009
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     Sending tick:Price: 0.0 time: Tue Jul 21 01:11:15 CEST 2009
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     Sending tick:Price: 7.0 time: Tue Jul 21 01:11:15 CEST 2009
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     Sending tick:Price: 4.0 time: Tue Jul 21 01:11:15 CEST 2009
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     Sending tick:Price: 9.0 time: Tue Jul 21 01:11:15 CEST 2009
    
    
   
   

   
   

    
    

   
   
   
   

    
    

     
     Event received: Price: 9.0 time: Tue Jul 21 01:11:15 CEST 2009
    
    
   
   
 
 

好了。esper可以使用了。