"Looking back and laughing at all kinds of beautiful people" means Spring Boot. At first, I just heard about this noun. What's the difference between spring and spring? The name is a little similar. So Spring Boot is an upgraded version of Spring, but it does not enhance Spring's functionality, but provides a quick way to use Spring: out-of-the-box, no code generation, and no XML configuration.
How to use SpringBook? First, create a general Maven project with a pom.xml and a basic src/main/java structure.
1. pom file configuration
<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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.nes.spring.boot</groupId>
<artifactId>SpringBootDemo1</artifactId>
<version>0.0.1-SNAPSHOT</version>
<!--spring-boot-starter-parent Contains a large number of well-configured dependency management, which does not need to be written when adding these dependencies to your project<version>version number-->
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.1.RELEASE</version>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!--spring-boot-starter-web Provided mvc,aop Dependency package-->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<!-- Compile -->
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.5.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
</configuration>
</plugin>
<!-- spring boot maven plugin -->
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
<dependencies>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>springloaded</artifactId>
<version>1.2.5.RELEASE</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
</project>
Note: Spring uses jdk1.6 by default. If you want to use jdk1.8, you need to add java.version to the properties of pom.xml.
2. New HelloController test class, pojo object Demo class, very common code.
@RestController
public class HelloController {
@RequestMapping("/hello")
public String hello(){
return "hello-2017";
}
@RequestMapping("/getDemo")
public Demo getDemo(){
Demo demo = new Demo();
demo.setId(1);
demo.setName("Stars");
demo.setCreateTime(new Date());
demo.setRemarks("Testing will you show up?");
return demo;
}
}
3. New Startup Class Application.java
@SpringBootApplication
public class Application extends WebMvcConfigurerAdapter {
//Start the program in main method
public static void main(String[] args) {
SpringApplication.run(Application.class,args);
}
}
Spring Boot is to boot a project using Spring Application, and the Spring Application class provides a convenient way for us to boot a project - by booting directly through the main() method. In most cases, we can delegate the project startup task directly to the SpringApplication.run method. Right-click run'Application. java'to start, and the console will be prompted accordingly.
4, problems
Error reporting at runtime: Caused by: org.spring framework.context.annotation.Conflicting Bean Definition Exception: Annotation-specified bean name'errorPageFilter'for bean class [org.spring framework.boot.web.support.ErrorPageFilter] conflicts with existing;
org.springframework.beans.factory.BeanDefinitionStoreException: Failed to parse configuration class [Application]; nested exception is org.springframework.context.annotation.ConflictingBeanDefinitionException: Annotation-specified bean name 'errorPageFilter' for bean class [org.springframework.boot.web.support.ErrorPageFilter] conflicts with existing, non-compatible bean definition of same name and class [org.springframework.boot.context.web.ErrorPageFilter]
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:187) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:324) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:246) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:273) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:98) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:681) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:523) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.4.1.RELEASE.jar:1.4.1.RELEASE]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:761) [spring-boot-1.4.1.RELEASE.jar:1.4.1.RELEASE]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:371) [spring-boot-1.4.1.RELEASE.jar:1.4.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-1.4.1.RELEASE.jar:1.4.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1186) [spring-boot-1.4.1.RELEASE.jar:1.4.1.RELEASE]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1175) [spring-boot-1.4.1.RELEASE.jar:1.4.1.RELEASE]
at Application.main(Application.java:12) [classes/:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_05]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_05]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_05]
at java.lang.reflect.Method.invoke(Method.java:483) ~[na:1.8.0_05]
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144) [idea_rt.jar:na]
Caused by: org.springframework.context.annotation.ConflictingBeanDefinitionException: Annotation-specified bean name 'errorPageFilter' for bean class [org.springframework.boot.web.support.ErrorPageFilter] conflicts with existing, non-compatible bean definition of same name and class [org.springframework.boot.context.web.ErrorPageFilter]
at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.checkCandidate(ClassPathBeanDefinitionScanner.java:320) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:259) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ComponentScanAnnotationParser.parse(ComponentScanAnnotationParser.java:137) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:275) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:237) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:204) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:173) ~[spring-context-4.3.3.RELEASE.jar:4.3.3.RELEASE]
... 18 common frames omitted
The first test item of pring boot reported an error, prompting errorPageFilter bean conflict, but the configuration class was not placed under the package. As long as you put it in a package at will, there will be no problem. Spring Boot does not need XML configuration. It automatically identifies files in a specific directory. If it is not placed under the package, it cannot recognize them. It should be like this.