How to invoke the AWS lambda function / handler from Java code

Question

I am new to AWS lambda I have created a lambda function with handler

example.Orders::orderHandler

And this is the custom handler, now I wa

Answer 1

The 2 methods in this class should be able to help you. One is for if you need to pass in a payload, the other if the payload is null.

However, you need to bear one thing in mind: the function name may not be the same as the handler (the latter here is example.Orders::orderHandler). The handler name is not used when invoking its function.

So, if you have a function with the function name 'myFunction' that behind the scenes call your example.Orders::orderHandler handler, then this is what you would pass into the run methods below.

import com.amazonaws.regions.Regions;
import com.amazonaws.services.lambda.AWSLambdaAsyncClient;
import com.amazonaws.services.lambda.model.InvokeRequest;
import com.amazonaws.services.lambda.model.InvokeResult;

class LambdaInvoker {

    public void runWithoutPayload(String region, String functionName) {
        runWithPayload(region, functionName, null);
    }

    public void runWithPayload(String region, String functionName, String payload) {
        AWSLambdaAsyncClient client = new AWSLambdaAsyncClient();
        client.withRegion(Regions.fromName(region));

        InvokeRequest request = new InvokeRequest();
        request.withFunctionName(functionName).withPayload(payload);
        InvokeResult invoke = client.invoke(request);
        System.out.println("Result invoking " + functionName + ": " + invoke);
    }
}