Swagger2: Failed to introspect Class [springfox.documentation.swagger2.configuration.Swagger2DocumentationConfiguration]

Question

I'm trying to use swagger2 in my project but getting below error.

"java.lang.IllegalStateException: Failed to introspect Class [springfox.documentation.swagger2.configuration.Swagger2DocumentationConfiguration] from ClassLoader [jdk.internal.loader.ClassLoaders$AppClassLoader@16f65612]"

//Spring Boot version: 2.1.9
//Swagger2: 2.9.2
//java: 11

package path.to.package;

import static springfox.documentation.builders.PathSelectors.regex;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import springfox.documentation.builders.RequestHandlerSelectors;
import springfox.documentation.spi.DocumentationType;
import springfox.documentation.spring.web.plugins.Docket;
import springfox.documentation.swagger2.annotations.EnableSwagger2;

@Configuration
@EnableSwagger2
public class SwaggerConfig {

  @Bean
  public Docket OrganizationApi() {
    return new Docket(DocumentationType.SWAGGER_2)
        .select()
        .apis(RequestHandlerSelectors.basePackage("path.to.package"))
        .paths(regex("/api/.*"))
        .build();
  }

}


<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger2 -->
<dependency>
  <groupId>io.springfox</groupId>
  <artifactId>springfox-swagger2</artifactId>
  <version>2.9.2</version>
</dependency>

<!-- https://mvnrepository.com/artifact/io.springfox/springfox-swagger-ui -->
<dependency>
  <groupId>io.springfox</groupId>
  <artifactId>springfox-swagger-ui</artifactId>
  <version>2.9.2</version>
</dependency>

Full StackTrace:

    at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:507)
    at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:404)
    at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:389)
    at org.springframework.util.ReflectionUtils.getUniqueDeclaredMethods(ReflectionUtils.java:447)
    at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1705)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod(AbstractAutowireCapableBeanFactory.java:738)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTargetType(AbstractAutowireCapableBeanFactory.java:679)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:647)
    at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1518)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:513)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:483)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:604)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeansOfType(DefaultListableBeanFactory.java:596)
    at org.springframework.context.support.AbstractApplicationContext.getBeansOfType(AbstractApplicationContext.java:1226)
    at org.springframework.boot.SpringApplication.getExitCodeFromMappedException(SpringApplication.java:866)
    at org.springframework.boot.SpringApplication.getExitCodeFromException(SpringApplication.java:854)
    at org.springframework.boot.SpringApplication.handleExitCode(SpringApplication.java:841)
    at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:792)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:322)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1204)
    at com.path.to.package.Application.main(Application.java:25)
Caused by: java.lang.NoClassDefFoundError: org/springframework/web/servlet/HandlerMapping
    at java.base/java.lang.Class.getDeclaredMethods0(Native Method)
    at java.base/java.lang.Class.privateGetDeclaredMethods(Class.java:3167)
    at java.base/java.lang.Class.getDeclaredMethods(Class.java:2310)
    at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:489)
    ... 21 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.web.servlet.HandlerMapping
    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)
    ... 25 common frames omitted

Binetta

Please share full stacktrace of the error. This can be related with a problem on your classpath. – Stoller

Caused by: java.lang.IllegalStateException: Failed to introspect Class [springfox.documentation.swagger2.configuration.Swagger2DocumentationConfiguration] from ClassLoader [jdk.internal.loader.ClassLoaders$AppClassLoader@2cdf8d8a] Caused by: java.lang.NoClassDefFoundError: org/springframework/web/servlet/HandlerMapping Caused by: java.lang.ClassNotFoundException: org.springframework.web.servlet.HandlerMapping – Binetta

Not sure if this is a compatibility issue. – Binetta

Spring Boot version: 2.1.9 Swagger2: 2.9.2 java: 11 – Binetta

Answer 1

java.lang.ClassNotFoundException: org.springframework.web.servlet.HandlerMapping means that you are missing a dependency in your pom.xml, to be precise you are missing spring-webmvc dependency.

As you are using Spring Boot, just add this dependency to your pom:

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Double check any other dependencies that may be missing. If you have any problem just post here your pom.xml and we can find the missing ones.

Stoller

Answer 2

Please try below code

@Configuration
public class SwaggerConfig implements WebMvcConfigurer {    
@Override
        public void addResourceHandlers(ResourceHandlerRegistry registry) {
            registry.addResourceHandler("/api/swagger-ui.html**").addResourceLocations("classpath:/META-INF/resources/swagger-ui.html");
            registry.addResourceHandler("/api/webjars/**").addResourceLocations("classpath:/META-INF/resources/webjars/");
        }

        @Bean
        public Docket api() {
            return new Docket(DocumentationType.SWAGGER_2).select()
                    .apis(RequestHandlerSelectors.basePackage("com.org.v1")).paths(PathSelectors.any())
                    .build().apiInfo(apiInfo());
        }

        private ApiInfo apiInfo() {
            return new ApiInfo("Service Name", "API Description", "API", "Terms of service",
                    new Contact("name", "webaddress", "email"), "License of API", "API license URL",
                    Collections.emptyList());
        }

Swagger Dependency been used with version 2.7.0

<dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger2</artifactId>
            <version>${swagger.version}</version>
            <scope>compile</scope>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-swagger-ui</artifactId>
            <version>${swagger.version}</version>
        </dependency>

@EnableSwagger2 can be at same place or main application class

Gerenuk

Look around your Maven Dependencies... Issue looks there – Gerenuk

Answer 3

<?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>3.0.1</version>
    <relativePath /> <!-- lookup parent from repository -->
</parent>
<groupId>com.user-registration</groupId>
<artifactId>registration</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>registration</name>
<description>Registration</description>
<properties>
    <java.version>17</java.version>
</properties>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger2</artifactId>
        <version>2.6.0</version>
    </dependency>

    <dependency>
        <groupId>io.springfox</groupId>
        <artifactId>springfox-swagger-ui</artifactId>
        <version>2.6.0</version>
    </dependency>

    <!-- 
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>
    
    -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-thymeleaf</artifactId>
    </dependency>


    <!--        <dependency>
        <groupId>org.thymeleaf.extras</groupId>
        <artifactId>thymeleaf-extras-springsecurity6</artifactId>
    </dependency>
-->

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>com.mysql</groupId>
        <artifactId>mysql-connector-j</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.20</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>
    <!-- 
    <dependency>
        <groupId>org.springframework.security</groupId>
        <artifactId>spring-security-test</artifactId>
        <scope>test</scope>
    </dependency>
    -->
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
    </plugins>
</build>

Tile

It didn't work for me, please help me out. Thanks in advance – Tile

As it’s currently written, your answer is unclear. Please edit to add additional details that will help others understand how this addresses the question asked. You can find more information on how to write good answers in the help center. – Phillipp