线程"main" java.lang.NoClassDefFoundError中的异常： org/springframework/boot/SpringApplication at com.javac

Question

我犯了那个错误，但我正在努力解决这个错误，真的不知道我为什么会犯错误？在stackoverflow中，我也犯了类似的错误。我试过了，但还是没用。我使用了java 1.8 jdk和弹簧引导2.3.2

pom.xml

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.3.2.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.javakerem</groupId>
<artifactId>SpringBootDemoo</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>SpringBootDemoo</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
<exclusions>
<exclusion>
<groupId>org.junit.vintage</groupId>
<artifactId>junit-vintage-engine</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>

SpringBootDemooApplication.java

package com.javakerem.SpringBootDemoo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class SpringBootDemooApplication {
public static void main(String[] args) {
SpringApplication.run(SpringBootDemooApplication.class, args);
}
}

产品控制器.java

package com.javakerem.SpringBootDemoo.apiTest;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class ProductsController {

@GetMapping("/")
public String get()
{
return "Kerem Kagan";
}

}   

我会写一点英语，如果我写错了，我很抱歉。

错误在于：

Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/boot/SpringApplication
at com.javacourse.springBootDemo.SpringBootDemoApplication.main(SpringBootDemoApplication.java:10)
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.SpringApplication
at java.net.URLClassLoader.findClass(URLClassLoader.java:382)
at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
... 1 more

Answer 1

1. cd通过cmd或git-bash 到THE_PROJECT_FOLDER

   mvn clean
   maven install
   maven package
   

2. 使用IDE转到项目，然后转到包含主方法的类

3. 点击@SpringBootApplication，看到左边一个像灯一样的图标

4. 点击它并选择下载maven

5. 运行应用

试试这个，它可能对你的很好