定制JMeter取样器

• JMeter运行你区定义自己的取样器sampler，方法很简单，只需继承类org.apache.jmeter.protocol.java.sampler.AbstractJavaSamplerClient，并重写若干方法即可。

• 首先，创建一个maven项目，并加入jmeter相关的依赖包：

 <dependencies>
     <dependency>
         <groupId>org.apache.jmeter</groupId>
         <artifactId>ApacheJMeter</artifactId>
         <version>2.10</version>
     </dependency>
     <dependency>
         <groupId>org.apache.jmeter</groupId>
         <artifactId>ApacheJMeter_core</artifactId>
         <version>2.10</version>
     </dependency>
     <dependency>
         <groupId>org.apache.jmeter</groupId>
         <artifactId>ApacheJMeter_http</artifactId>
         <version>2.10</version>
     </dependency>
     <dependency>
         <groupId>org.apache.jmeter</groupId>
         <artifactId>ApacheJMeter_java</artifactId>
         <version>2.10</version>
     </dependency>
 </dependencies>

• 然后，创建一个类，继承自AbstractJavaSamplerClient，并重写setupTest、teardownTest、runTest与getDefaultParameters方法即可

• 代码示例如下：

 package pengliu.me.jmeter.plugins;

 import org.apache.jmeter.config.Arguments;
 import org.apache.jmeter.protocol.java.sampler.AbstractJavaSamplerClient;
 import org.apache.jmeter.protocol.java.sampler.JavaSamplerContext;
 import org.apache.jmeter.samplers.SampleResult;
 import org.apache.jorphan.logging.LoggingManager;
 import org.apache.log.Logger;

 import java.util.Iterator;
 import java.util.Random;

 public class MySampler extends AbstractJavaSamplerClient
 {
     private static final Logger log = LoggingManager.getLoggerForClass();

     @Override
     public void setupTest(JavaSamplerContext context)
     {
         Iterator<String> it = context.getParameterNamesIterator();
         while (it.hasNext())
         {
             String paramName =  it.next();
             this.log.info(String.format("-----------------paramName: %s, paramValue: %s-----------------",
                     paramName,
                     context.getParameter(paramName)));
         }

         this.log.info(String.format("-----------------Get param 'name' from JMeter: %s-----------------",
                 context.getParameter("name", "Default Name")));
         this.log.info(String.format("-----------------Current Thread Id: %s, Start 'setupTest(JavaSamplerContext context)'--------------------",
                 Thread.currentThread().getId()));
     }

     @Override
     public void teardownTest(JavaSamplerContext context)
     {
         this.log.info(String.format("-----------------Current Thread Id: %s, Start 'teardownTest(JavaSamplerContext context)'--------------------",
                 Thread.currentThread().getId()));
     }

     public SampleResult runTest(JavaSamplerContext javaSamplerContext)
     {
         SampleResult result = new SampleResult();
         result.sampleStart();
         try
         {
             Random r = new Random();
             long sleepTime = (long)r.nextInt(5000);
             this.log.info(String.format("-----------------Current Thread Id: %s, Running Test, sleep time is %s--------------------",
                     Thread.currentThread().getId(),
                     sleepTime));
             Thread.sleep(sleepTime);

             if(sleepTime%2 == 0)
             {
                 throw new Exception("--------This is my exception from runTest!!!---------");
             }

             result.sampleEnd();
             result.setSuccessful(true);
             result.setSampleLabel("My Lable: SUCCESS: " + Thread.currentThread().getId());
         }
         catch (Throwable e)
         {
             result.sampleEnd();
             result.setSuccessful(false);
             result.setSampleLabel("My Lable: FAIL: " + Thread.currentThread().getId());

             e.printStackTrace();
         }

         return result;
     }

     @Override
     public Arguments getDefaultParameters() {

         Arguments params = new Arguments();

         params.addArgument("name", "edw");

         return params;
     }
 }

• 其中setupTest与teardownTest方法，在一个线程只被执行一次，无论此Thread Group配置的Loop Count是多少，每个线程只运行一次这两个方法。

• 其中runTest方法，如果一个线程配置了多次的Loop Count，那么此runTest就会运行多次

• 其中getDefaultParameters方法，返回的是JMeter界面的参数列表，如下图：
  

• 使用”mvn package”命令打包上面的sampler:

• 将打包好的jar包放到JMeter的lib/ext目录下：

• 启动JMeter, 并加入一个Java Request的sampler:

• Classname选择代码中自定义的sampler类： 

• 配置Thread Group，线程数为２，循环数为５：

• 选中Java Request这个sampler，可以设置参数name的值

• 开始执行后，JMeter会产生两个线程，每个线程都跑只跑一遍setupTest与teardownTest方法，但会跑５遍runTest方法

• 查看JMeter的日志输出：

• 查看”View Results in Table”中的结果：