AWS Lambda NoClassDefFoundError [英] AWS Lambda NoClassDefFoundError

问题描述

我在使用基于 Java 的 Lambda 函数设置接收来自 SNS 的消息时遇到困难.我的函数如下所示:

I am having difficulty with a Java based Lambda function setup to receive messages from SNS. My function looks like the below:

package com.mycompany;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.LambdaLogger;
import com.amazonaws.services.lambda.runtime.events.SNSEvent;

public class LambdaHandler {  
    public void Handler(SNSEvent event, Context context) {
        //Process the event
    }
}

它编译得很好，我将 jar 文件上传到 Lambda(通过网络控制台)没有任何问题.

It compiles just fine and I don't have any problems uploading the jar file to Lambda (via the web console).

但是，当我使用表示 SNSEvent 模型的 JSON 向它发布(通过 SNS 到订阅的 Lambda 函数)时，Lambda 函数会引发以下异常:

However, when I publish to it (via SNS through to the subscribed Lambda function) with JSON representing the SNSEvent model, the Lambda function throws the following exception:

在 com.mycompany.LambdaHandler 类上加载方法处理程序时出错:类 java.lang.NoClassDefFoundError java.lang.NoClassDefFoundError:com/amazonaws/services/lambda/runtime/events/SNSEvent 位于

Error loading method handler on class com.mycompany.LambdaHandler: class java.lang.NoClassDefFoundError java.lang.NoClassDefFoundError: com/amazonaws/services/lambda/runtime/events/SNSEvent at

java.lang.Class.getDeclaredMethods0(Native Method) 在java.lang.Class.privateGetDeclaredMethods(Class.java:2701) 在java.lang.Class.privateGetPublicMethods(Class.java:2902) 在java.lang.Class.getMethods(Class.java:1615) 引起:java.lang.ClassNotFoundException:com.amazonaws.services.lambda.runtime.events.SNSEvent 在java.net.URLClassLoader.findClass(URLClassLoader.java:381) 在java.lang.ClassLoader.loadClass(ClassLoader.java:424) 在java.lang.ClassLoader.loadClass(ClassLoader.java:357)

java.lang.Class.getDeclaredMethods0(Native Method) at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) at java.lang.Class.privateGetPublicMethods(Class.java:2902) at java.lang.Class.getMethods(Class.java:1615) Caused by: java.lang.ClassNotFoundException: com.amazonaws.services.lambda.runtime.events.SNSEvent at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

我使用 Maven + Netbeans，这是一个 Maven Java 应用程序项目.我从 Lambda 控制台下载了该函数并确认，jar 有一个 lib/目录，其中包含用于导入的所有 jar，包括 aws-lambda-java-events-1.1.0.jar，它本身包含/com/amazonaws/services/lambda/runtime/events/SNSEvent.class 文件.

I use Maven + Netbeans and it's a Maven Java Application project. I downloaded the function from the Lambda console and confirmed, the jar has a lib/ directory with all of the jar's for the imports, including aws-lambda-java-events-1.1.0.jar, which itself includes the /com/amazonaws/services/lambda/runtime/events/SNSEvent.class file.

当类肯定在 jar 文件中时，为什么运行时无法找到它?我还有什么需要做的吗，设置任何环境变量等?

Why is the runtime unable to find the class when it's definitely in the jar file? Is there anything else I need to do, set any environment variables, etc?

任何帮助将不胜感激！

编辑 1我尝试降级到 aws-lambda-java-events 1.0.0，但它仍然报告相同的异常.根据要求，下面是我的 POM 文件(仅更改了项目名称).我不知道如何告诉 Maven 将库放在树结构中.

EDIT 1 I tried downgrading to aws-lambda-java-events 1.0.0 and it's still reporting the same exception. As requested, below is my POM file (with just project name changed). I don't know how to tell Maven to put the libraries in a tree structure.

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.app</groupId>
    <artifactId>Handler</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>
    <dependencies>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-java-sdk-lambda</artifactId>
            <version>1.10.6</version>
        </dependency>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-core</artifactId>
            <version>1.0.0</version>
        </dependency>
        <dependency>
            <groupId>com.amazonaws</groupId>
            <artifactId>aws-lambda-java-events</artifactId>
            <version>1.0.0</version>
        </dependency>
    </dependencies>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
    </properties>
</project>

推荐答案

使用 maven-shade 插件，以便 JAR 包含 uber-jar 中的依赖项.

Use the maven-shade plugin so that the JAR contains the dependencies in an uber-jar.

因此，将其添加到您的 pom.xml

So, add this to your pom.xml

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-shade-plugin</artifactId>
        <version>2.3</version>
        <configuration>
          <createDependencyReducedPom>false</createDependencyReducedPom>
        </configuration>
        <executions>
          <execution>
            <phase>package</phase>
            <goals>
              <goal>shade</goal>
            </goals>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>

来源:http://docs.aws.amazon.com/lambda/latest/dg/java-create-jar-pkg-maven-no-ide.html

您可能有这个问题 https://github.com/aws/aws-lambda-java-libs/issues/2 需要降级到 aws-lambda-java-events-1.0.0.jar

Potentially you may have this issue https://github.com/aws/aws-lambda-java-libs/issues/2 which requires a downgrade to aws-lambda-java-events-1.0.0.jar

这篇关于AWS Lambda NoClassDefFoundError的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！