java - Ektorp 依赖导致 Spring boot 应用程序崩溃

Question

我正在制作一个网络应用程序。后端是Java的，我用的是Spring。对于数据库我使用CouchDb并且我想使用Ektorp，但是问题来了。当我添加 Ektorp 依赖项时它崩溃了。它可以编译，但是当我尝试运行时，我收到下面的错误。

Exception in thread "main" java.lang.IllegalArgumentException: Cannot instantiate interface org.springframework.context.ApplicationListener : org.springframework.boot.context.logging.ClasspathLoggingApplicationListener
    at org.springframework.boot.SpringApplication.createSpringFactoriesInstances(SpringApplication.java:450)
    at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:429)
    at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:420)
    at org.springframework.boot.SpringApplication.<init>(SpringApplication.java:270)
    at org.springframework.boot.SpringApplication.<init>(SpringApplication.java:249)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
    at QEasyApplication.main(QEasyApplication.java:18)
Caused by: java.lang.NoClassDefFoundError: org/springframework/context/event/GenericApplicationListener
    at java.base/java.lang.ClassLoader.defineClass1(Native Method)
    at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
    at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
    at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:398)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:275)
    at org.springframework.boot.SpringApplication.createSpringFactoriesInstances(SpringApplication.java:442)
    ... 7 more
Caused by: java.lang.ClassNotFoundException: org.springframework.context.event.GenericApplicationListener
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    ... 20 more

Process finished with exit code 1

我尝试更改为不同版本的 Ektorp 或 Spring Boot，但没有任何效果。下面是我的 Maven pom 文件。可能是什么问题呢？

<?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>

    <properties>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-dependencies</artifactId>
            <version>2.1.3.RELEASE</version>
            <type>pom</type>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>


        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-logging</artifactId>
            <version>2.1.3.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.ektorp</groupId>
            <artifactId>org.ektorp.spring</artifactId>
            <version>1.4.4</version>
        </dependency>
    </dependencies>
</project>

Answer 1

嗯，看来org.springframework.context.event.GenericApplicationListener不在你的类路径上。它位于 spring-context .

您声明，换句话说您的 pom.xml指出，有人应该提供 spring-boot-dependencies为你？我认为你混淆了 provided和 import Maven scopes :

• provided –“您期望 JDK 或容器在运行时提供依赖项”
• import – “它指示要替换为指定 POM 部分中的有效依赖项列表的依赖项。”

有两种可能性:

1. 切换 runtime spring-boot-dependencies的范围至import
2. 更好，让 Spring Boot 为您管理尽可能多的依赖项，并将以下父 pom 放置到位，以充分利用 Spring Boot 的潜力:

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.3.RELEASE</version>
    </parent>