JMeter get var - Java

JMeter is a powerful tool for load testing and performance measurement of web applications. It provides various features to simulate user behavior and monitor the performance of the application under different load conditions.

One of the key features of JMeter is the ability to extract and use variables from the server response. This is useful when you need to use a value from a server response to make a subsequent request.

In Java, you can use the JMeter API to extract and use variables in your test plan. Here is an example of how to extract a variable from a server response using the JMeter API:

import org.apache.jmeter.protocol.http.sampler.HTTPSampleResult;

public class GetVariable {

    public static String getVar(HTTPSampleResult result, String varName) {
        String body = new String(result.getResponseData());
        String regex = varName + "\\s*=\\s*(\\S*)";
        Pattern pattern = Pattern.compile(regex);
        Matcher matcher = pattern.matcher(body);
        if (matcher.find()) {
            return matcher.group(1);
        } else {
            return null;
        }
    }

}

Here, the getVar method takes an HTTPSampleResult object and the variable name as input parameters. It then extracts the variable value using a regular expression and returns it.

Note that this is just an example and you may need to modify the regular expression to match the variable format used in your server response.

To use this method in your test plan, you can call it from a Sampler as follows:

import org.apache.jmeter.protocol.http.sampler.HTTPSampler;
import org.apache.jmeter.protocol.http.sampler.HTTPSampleResult;

public class MySampler extends HTTPSampler {

    @Override
    public HTTPSampleResult sample(URL url, String method, boolean followRedirects) {
        
        // Make HTTP request here and get response
        ...
        
        // Extract variable using getVar method
        String myVar = GetVariable.getVar(result, "myVar");
        
        // Use variable in subsequent request
        ...
        
        // Return HTTPSampleResult
        return result;
    }

}

In this example, the sample method of a custom HTTPSampler class is overridden to extract a variable from the response. The getVar method from the previous example is used to extract the variable value and then it is used in a subsequent request.

Overall, JMeter provides a powerful API for extracting and using variables from server responses in your test plan. You can use this feature to simulate user behavior in your application under different load conditions and monitor its performance.