跟杨春娟学SpringBoot笔记：Spring中 JavaConfig和常见注解

完成：第一遍

1.创建一个SpringFramework项目框架项目准备工作有哪些?

步骤一：File——》maven project

步骤二：勾选Create a simple project

步骤三：Group Id:com.adbycool

Artifact Id:JavaConfigProject
Name:JavaConfigProject
点finish

步骤四：点击pom.xml，直接add Spring-webmvc的jar包依赖

2.常见Java Config注解有哪些？

@Configuration注解：把当前文件配置成配置文件

@ComponentScan注解：把当前包和子包进行扫描
@PropertySource JDK版本高于等于JDK8的用法：把需要的properties文件引进
@PropertySources({@PropertySource(“classpath:file1.properties”)JDK版本低于JDK8的用法

@Import(ScanConfig.class)：把相关文件配置到一起
@ImportResource(“classpath:applicationContext.xml”)

pom.xml


     
    
     4.0.0
      
    
     com.java.config.demo
      
    
     JavaConfigProject
      
    
     0.0.1-SNAPSHOT
      
    
     Java Config Project
      
      	
       		
      
       org.springframework
        		
      
       spring-webmvc
        		
      
       5.2.4.RELEASE

HelloWorld

package com.java.config.demo;public class HelloWorld {
   	public void sayHello() {
   		System.out.println("-----say hello");	}}

src/main/resources下的applicationContext.xml

APP

package com.java.config.demo;import org.springframework.context.ApplicationContext;import org.springframework.context.annotation.AnnotationConfigApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.java.config.demo.scan.ScanHelloWorld;public class APP {
   	public static void main(String[] args) {
   		// TODO Auto-generated method stub		/*ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");		HelloWorld helloWorld = context.getBean("hello", HelloWorld.class);		helloWorld.sayHello();*/				//@Configuration		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();		context.register(HelloConfig.class);		context.refresh();		HelloWorld helloWorld = context.getBean(HelloWorld.class);		helloWorld.sayHello();		ScanHelloWorld scan = context.getBean(ScanHelloWorld.class);		scan.sayHello();				//component-scan for xml file		/*ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");		ScanHelloWorld scan = context.getBean("scanHelloWorld", ScanHelloWorld.class);		scan.sayHello();*/				/*AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();		context.register(ScanConfig.class);		context.refresh();		ScanHelloWorld scan = context.getBean(ScanHelloWorld.class);		scan.sayHello();*/	}}

HelloConfig类来演示@Configuration注解

package com.java.config.demo;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Import;import org.springframework.context.annotation.ImportResource;@Configuration@Import(ScanConfig.class)@ImportResource("classpath:applicationContext.xml")public class HelloConfig {
   	@Bean	public HelloWorld helloWorld() {
   		return new HelloWorld();	}}

ScanConfig类来演示@ComponentScan注解

package com.java.config.demo;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.PropertySource;import org.springframework.context.annotation.PropertySources;@ComponentScan@PropertySource("classpath:file1.properties")@PropertySource("classpath:file2.properties")//jdk版本低于jdk8//@PropertySources({@PropertySource("classpath:file1.properties"), @PropertySource("classpath:file2.properties")})public class ScanConfig {
   }

ScanHelloWorld

package com.java.config.demo.scan;import org.springframework.stereotype.Component;@Component("scanHelloWorld")public class ScanHelloWorld {
   	public void sayHello() {
   		System.out.println("--------scan");	}}

file1.properties

file2.properties
如果有多个配置文件.properties可以用
@PropertySource(“classpath:file1.properties”)
@PropertySource(“classpath:file2.properties”)
来配置

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