SpringBoot 2.1.x 启动报错：java.lang.ClassNotFoundException: org.springframework.boot.bind.RelaxedDataBin

使用alibaba的druid数据库连接池时，启动报错，报错信息如下：

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [com/alibaba/druid/spring/boot/autoconfigure/DruidDataSourceAutoConfigure.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/boot/bind/RelaxedDataBinder
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:627) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:607) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1321) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1160) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1248) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1168) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	... 61 common frames omitted
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/boot/bind/RelaxedDataBinder
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:622) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	... 75 common frames omitted
Caused by: java.lang.NoClassDefFoundError: org/springframework/boot/bind/RelaxedDataBinder
	at com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder.bind(DruidDataSourceBuilder.java:48) ~[druid-spring-boot-starter-1.1.0.jar:na]
	at com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceBuilder.build(DruidDataSourceBuilder.java:41) ~[druid-spring-boot-starter-1.1.0.jar:na]
	at com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure.dataSource(DruidDataSourceAutoConfigure.java:44) ~[druid-spring-boot-starter-1.1.0.jar:na]
	at com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure$$EnhancerBySpringCGLIB$$f9b56e9b.CGLIB$dataSource$0() ~[druid-spring-boot-starter-1.1.0.jar:na]
	at com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure$$EnhancerBySpringCGLIB$$f9b56e9b$$FastClassBySpringCGLIB$$190ccbca.invoke() ~[druid-spring-boot-starter-1.1.0.jar:na]
	at org.springframework.cglib.proxy.MethodProxy.invokeSuper(MethodProxy.java:244) ~[spring-core-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassEnhancer$BeanMethodInterceptor.intercept(ConfigurationClassEnhancer.java:363) ~[spring-context-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	at com.alibaba.druid.spring.boot.autoconfigure.DruidDataSourceAutoConfigure$$EnhancerBySpringCGLIB$$f9b56e9b.dataSource() ~[druid-spring-boot-starter-1.1.0.jar:na]
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_77]
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_77]
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_77]
	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_77]
	at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
	... 76 common frames omitted
Caused by: java.lang.ClassNotFoundException: org.springframework.boot.bind.RelaxedDataBinder
	at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_77]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_77]
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) ~[na:1.8.0_77]
	at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_77]
	... 89 common frames omitted

原因

由于springboot2.X在1.x的基础上废除 org.springframework.boot.bind.RelaxedDataBinder。

解决办法

1、将版本回退到1.x

2、直接使用jdbc连接

3、将druid版本调到1.1.13