• ctx - ( JMeterContext) - gives access to the context
• vars - ( JMeterVariables) - gives read/write access to variables: vars.get(key); vars.put(key,val); vars.putObject("OBJ1",new Object()); vars.getObject("OBJ2");
• props - (JMeterProperties - class java.util.Properties) - e.g. props.get("START.HMS"); props.put("PROP1","1234");
• prev - ( SampleResult) - gives access to the previous SampleResult (if any)
• sampler - (Sampler)- gives access to the current sampler

ctx 地址：http://jmeter.apache.org/api/org/apache/jmeter/threads/JMeterContext.html

vars 地址：http://jmeter.apache.org/api/org/apache/jmeter/threads/JMeterVariables.html

prev地址：http://jmeter.apache.org/api/org/apache/jmeter/samplers/SampleResult.html

其中vars、prev类很常用、api中介绍了一些方法