Spring Boot For Kotlin学习

开发环境准备:

IDE：spring tools suite 4

Kotlin插件：

1. 在sts中打开搜索界面：

   
   
   

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   2.搜索kotlin，然后点击install：

   
   
   

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   3.等待安装完成。并且重启sts

开始spring boot项目创建

1. 点击file->new->Spring starter project。设置项目名字ID等信息，点击Next

   
   
   

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2. 这里先就选择web。后续再慢慢加入其他jar包。点击Finish。等待项目安装好

   
   
   

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3. 项目建号完成。可能会出现以下错误。点击maven->update一下就好

   
   
   

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   4.最终完成。得到项目。感觉和java项目一样 ，只是文件的后缀改成了.kt

   
   
   

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开始hello world

1.新建一个kotlin文件.标准的springMVC注解。因为这里没有使用页面，所以使用@RestController注解直接返回值

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2.启动项目。访问 本机地址,http://localhost:8080

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3。启动的时候可能会报错.

org.springframework.beans.factory.parsing.BeanDefinitionParsingException: Configuration problem: @Configuration class 'ShisyatKotlinApplication' may not be final. Remove the final modifier to continue.
Offending resource: edu.shisyat.ShisyatKotlinApplication
    at org.springframework.beans.factory.parsing.FailFastProblemReporter.error(FailFastProblemReporter.java:72) ~[spring-beans-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClass.validate(ConfigurationClass.java:217) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.validate(ConfigurationClassParser.java:208) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:316) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:232) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:705) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:531) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
    at edu.shisyat.ShisyatKotlinApplicationKt.main(ShisyatKotlinApplication.kt:13) [classes/:na]

出现上面问题只需要在启动类class前面加上open，原因是因为：kotlin中所有类和方法默认都是final的,不能直接继承或重写，而@SpringBootApplication注解中用到@Configuration所以类不可以是final类型，这就导致报错

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今天到处结束