maven项目转成spring boot项目有两种方式

maven项目转成spring boot项目有两种方式：

1、继承方式，pom.xml文件中配置

    <parent>
        <groupId>org.springframework.bootgroupId>
        <artifactId>spring-boot-starter-parentartifactId>
        <version>1.5.9.RELEASEversion>
    parent>

2、导入pom文件的方式，在pom.xml文件中导入spring-boot-dependencies工程pom文件

<dependencyManagement>
     <dependencies>
        <dependency>
            <groupId>org.springframework.bootgroupId>
            <artifactId>spring-boot-dependenciesartifactId>
            <version>1.5.9.RELEASEversion>
            <type>pomtype>
            <scope>importscope>
        dependency>
    dependencies>
dependencyManagement>

针对第二种方式，主要是解决需要继承自定义父工程的场景，因为在spring-boot-dependencies的pom中已经定义了很多依赖管理dependencyManager，因此在自有父工程的pom中不要出现依赖管理和spring-boot-dependencies存在冲突的情况，比如导入的spring-boot-dependencies版本是1.5.9.release，那么默认就导入了如下的依赖管理

<dependencyManagement>
        <dependencies>
            
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-bootartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-testartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-test-autoconfigureartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-actuatorartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-actuator-autoconfigureartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-autoconfigureartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-autoconfigure-processorartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            <dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-configuration-metadataartifactId>
                <version>1.5.9.releaseversion>
            dependency>
            ........

如果在项目的其他pom文件中也增加了依赖管理，出现了版本不一致的情况如下

<dependency>
                <groupId>org.springframework.bootgroupId>
                <artifactId>spring-boot-actuator-autoconfigureartifactId>
                <version>1.3.5.releaseversion>
            dependency>

那么如果该依赖dependency到项目中，启动时会出现类库冲突异常，如下

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v1.5.9.RELEASE)

2017-12-27 01:44:25.572  INFO 23408 --- [           main] com.ibm.edp.dictionary.Startup           : Starting Startup on xujian-PC with PID 23408 (D:\projects\ibm\edp\edp-dictionary\edp-dictionary-web\target\classes started by xujian in D:\projects\ibm\edp\edp-dictionary\edp-dictionary-web)
2017-12-27 01:44:25.576  INFO 23408 --- [           main] com.ibm.edp.dictionary.Startup           : The following profiles are active: dev
2017-12-27 01:44:25.704  INFO 23408 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@4fe767f3: startup date [Wed Dec 27 01:44:25 CST 2017]; root of context hierarchy
2017-12-27 01:44:26.204  WARN 23408 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [com.ibm.edp.dictionary.Startup]; nested exception is java.lang.IllegalArgumentException: Cannot instantiate factory class: org.springframework.boot.autoconfigure.AutoConfigurationImportFilter
2017-12-27 01:44:26.450 ERROR 23408 --- [           main] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.BeanDefinitionStoreException: Failed to process import candidates for configuration class [com.ibm.edp.dictionary.Startup]; nested exception is java.lang.IllegalArgumentException: Cannot instantiate factory class: org.springframework.boot.autoconfigure.AutoConfigurationImportFilter
    at org.springframework.context.annotation.ConfigurationClassParser.processDeferredImportSelectors(ConfigurationClassParser.java:462) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:186) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:321) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:243) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:273) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:98) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:678) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:520) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) ~[spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) ~[spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) ~[spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.builder.SpringApplicationBuilder.run(SpringApplicationBuilder.java:134) [spring-boot-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at com.ibm.edp.dictionary.Startup.main(Startup.java:26) [classes/:na]
Caused by: java.lang.IllegalArgumentException: Cannot instantiate factory class: org.springframework.boot.autoconfigure.AutoConfigurationImportFilter
    at org.springframework.core.io.support.SpringFactoriesLoader.instantiateFactory(SpringFactoriesLoader.java:138) ~[spring-core-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.core.io.support.SpringFactoriesLoader.loadFactories(SpringFactoriesLoader.java:91) ~[spring-core-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.getAutoConfigurationImportFilters(AutoConfigurationImportSelector.java:280) ~[spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.filter(AutoConfigurationImportSelector.java:251) ~[spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.boot.autoconfigure.AutoConfigurationImportSelector.selectImports(AutoConfigurationImportSelector.java:102) ~[spring-boot-autoconfigure-1.5.9.RELEASE.jar:1.5.9.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.processDeferredImportSelectors(ConfigurationClassParser.java:454) ~[spring-context-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    ... 13 common frames omitted
Caused by: java.lang.IllegalAccessException: Class org.springframework.core.io.support.SpringFactoriesLoader can not access a member of class org.springframework.boot.autoconfigure.condition.OnClassCondition with modifiers ""
    at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:102) ~[na:1.8.0_101]
    at java.lang.Class.newInstance(Class.java:436) ~[na:1.8.0_101]
    at org.springframework.core.io.support.SpringFactoriesLoader.instantiateFactory(SpringFactoriesLoader.java:135) ~[spring-core-4.2.6.RELEASE.jar:4.2.6.RELEASE]
    ... 18 common frames omitted

因此在管理spring boot项目时，一定要保证依赖的类库版本是一致的