Spring基础配置---Java配置文件编写

一、概念解析#

java配置是通过@Configuration、@Bean实现。
@Configuration声明当前类是一个配置类，相当于一个Spring的XML配置文件。
@Bean注解到方法上声明当前方法返回值是一个Bean。

二、Demo#

1、一个功能类的Bean

package com.springconfig.test;
public class FunctionService(){
    public String printHappy(String UserName){
      return UserName+"Happy";
  }
}

2、使用功能类的Bean

package com.springconfig.test;
public class UseFunctionService(){
FunctionService functionService;
    public void setFunctionService(FunctionService functionService){
      this.functionService = functionService;
    }
    public String printHappy(String UserName){
      return functionService.printHappy(UserName);
  }
}

3、配置类

//第一种方式
package com.springconfig.test;
@Configuration
public class JavaConfig(){
//声明这个方法返回一个Bean，Bean的名字就是方法名。此处应该返回functionService这个Bean
    @Bean
    public FunctionService functionService(){
       return new FunctionService ();
    }

  @Bean
    public UseFunctionService useFunctionService(){
      UseFunctionService useFunctionService = new useFunctionService()；
      //给useFunctionService 这个Bean注入functionService()方法返回的Bean
      useFunctionService .setFunctionService(functionService())
      return useFunctionService;
  }
}

//第二种方式
package com.springconfig.test;
@Configuration
public class JavaConfig(){
  @Bean
    //直接将FunctionService 这个Bean作为参数传入useFunctionService()方法
    public UseFunctionService useFunctionService(FunctionService functionService){
        UseFunctionService useFunctionService = new useFunctionService()；
        //注入functionService这个Bean 
        useFunctionService .setFunctionService(functionService)
        return useFunctionService;
  }
}

4、Main启动类

package com.springconfig.test;

import org.springframework.context.annotation.AnnotationConfigApplicationContext;

public class Main(){

    public static void main(String[] args){

//使用Spring  AnnotationConfigApplicationContext容器读取Config这个配置类

AnnotationConfigApplicationContext comtext = new             AnnotationConfigApplicationContext(JavaConfig.class);

//获取context容器中的实例化Bean  UseFunctionService

UseFunctionService useFunctionService = context.getBean(UseFunctionService.class);

system.out.println(useFunctionService.printHappy("冉玉琦"));

context.close();

}

}