Help Center/ FunctionGraph/ Developer Guide/ Java/ Developing a Java Event Function/ Developing Functions in Java (Using IDEA to Create a Java Project)
Updated on 2025-12-10 GMT+08:00
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Developing Functions in Java (Using IDEA to Create a Java Project)

This section describes how to use IDEA to develop Java functions. For details about the Java syntax, initializer and SDK APIs, see Function Development Overview.

Procedure

You can create a Java project and Java function following the steps in this section, or download the sample project package and start from Step 3: Creating and Testing a Java Function.

Step 1: Creating a Java Project Using IDEA

  1. Configure the IDEA.
    Create a Java project, as shown in Figure 1.
    Figure 1 Creating a project
  2. Add dependencies to the project.

    Download the Java SDK to a local development environment, and decompress the SDK package, as shown in Figure 2.

    Figure 2 Decompressing the downloaded SDK
  3. Configure dependencies.

    Create a folder named lib in the project directory, copy the Runtime2.0.5.jar file and other required dependencies to the lib folder, and add the JAR files as the dependencies of the project, as shown in Figure 3.

    Figure 3 Configuring dependencies
  4. Configure the function resources.

    Create a package named com.huawei.demo, and then create a class named TriggerTests under the package, as shown in Figure 4.

    Figure 4 Creating the TriggerTests class
  5. Configure the function code.
    Define the function handler in TriggerTests.java as shown in Figure 5. The sample code is as follows: A common Java project needs to be compiled using artifacts, and a main function needs to be defined. 
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    package com.huawei.demo;

import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Map;

import com.huawei.services.runtime.Context;
import com.huawei.services.runtime.entity.apig.APIGTriggerEvent;
import com.huawei.services.runtime.entity.apig.APIGTriggerResponse;
import com.huawei.services.runtime.entity.dis.DISTriggerEvent;
import com.huawei.services.runtime.entity.dms.DMSTriggerEvent;
import com.huawei.services.runtime.entity.lts.LTSTriggerEvent;
import com.huawei.services.runtime.entity.smn.SMNTriggerEvent;
import com.huawei.services.runtime.entity.timer.TimerTriggerEvent;
import com.huawei.services.runtime.entity.eventgrid.EventGridTriggerEvent;

public class TriggerTests {
    public static void main(String args[]) {}
    public APIGTriggerResponse apigTest(APIGTriggerEvent event, Context context){
        System.out.println(event);
        Map<String, String> headers = new HashMap<String, String>();
        headers.put("Content-Type", "application/json");
        return new APIGTriggerResponse(200, headers, event.toString());
    }

    public String smnTest(SMNTriggerEvent event, Context context){
        System.out.println(event);
        return "ok";
    }

    public String dmsTest(DMSTriggerEvent event, Context context){
        System.out.println(event);
        return "ok";
    }

    public String timerTest(TimerTriggerEvent event, Context context){
        System.out.println(event);
        return "ok";
    }

    public String disTest(DISTriggerEvent event, Context context) throws UnsupportedEncodingException{
        System.out.println(event);
        System.out.println(event.getMessage().getRecords()[0].getRawData());
        return "ok";
    }

    public String ltsTest(LTSTriggerEvent event, Context context) throws UnsupportedEncodingException {
        System.out.println(event);
        event.getLts().getData();
        System.out.println("raw data: " + event.getLts().getRawData());
        return "ok";
    }

    public String eventgridTest(EventGridTriggerEvent event, Context context){
        System.out.println(event);return "ok";
    }
}
    Figure 5 Defining the function handler

    There are multiple handler functions with different trigger event types. You can modify the handler on the FunctionGraph console to test different handler functions. For details about the constraints for the APIG event source, see Base64 Decoding and Response Structure.

    Modifying the function handler:

    In the navigation pane on the left of the FunctionGraph console, choose Functions > Function List. Click the name of the function to be set. On the function details page that is displayed, choose Configuration > Basic Settings and set the Handler parameter, as shown in Figure 6.
    Figure 6 Function handler

Step 2: Packaging a Java Project

  1. Choose File > Project Structure. The Project Structure page is displayed, as shown in Figure 7.
    Figure 7 Going to the Project Structure page
  2. Choose Artifacts and click + to add artifacts, as shown in Figure 8.
    Figure 8 Adding artifacts
  3. Add a main class, as shown in Figure 9.
    Figure 9 Adding a main class
  4. Choose Build > Build Artifacts to compile the JAR file, as shown in Figure 10.
    Figure 10 Choosing Build Artifacts to compile the JAR file

Step 3: Creating and Testing a Java Function

  1. Log in to the FunctionGraph console. In the navigation pane on the left, choose Functions > Function List. On the displayed page, click Create Function in the upper right corner. On the displayed page, select Create from scratch.
  2. Configure the basic function information, as shown in Figure 11. Set Runtime to Java 17. After the configuration is complete, click Create Function in the lower right corner.
    Figure 11 Creating a Java function

  3. On the function details page, click the Code tab, and click Upload > Local JAR on the right to upload the JAR file exported in Step 2: Packaging a Java Project, as shown in Figure 12.
    Figure 12 Uploading a JAR file
  4. After the upload is successful, choose Configuration > Basic Settings, modify the handler of the function to be tested, and click Save.
  5. Return to the Code tab page, click Test in the code editing area, and click Configure Test Event. In the cloud event template list, select the event template to be tested and click Create.
  6. Click Test and view the execution result.

    The function execution result consists of three parts: function output (returned by callback), summary, and logs (output by using the console.log or getLogger() method). For details, see Table 1.

    Table 1 Description of the execution result

    Parameter

    Successful Execution

    Failed Execution

    Function Output

    The defined function output information is returned.

    A JSON file that contains errorMessage and stackTrace is returned. The format is as follows:

    {
  "errorMessage": "",
  "stackTrace": []
}

    errorMessage: Error message returned by the runtime.

    stackTrace: Stack error information returned by the runtime.

    Summary

    Request ID, Memory Configured, Execution Duration, Memory Used, and Billed Duration are displayed.

    Request ID, Memory Configured, Execution Duration, Memory Used, and Billed Duration are displayed.

    Log Output

    Function logs are printed. A maximum of 4 KB logs can be displayed.

    Error information is printed. A maximum of 4 KB logs can be displayed.

    To test other event source triggers in the sample code, such as SMN, change the handler to com.huawei.demo.TriggerTests.smnTest on the Basic Settings page, and create an SMN test event to test the function.