spring 组件基于注解的注册方式

spring 中常用的组件标签有：

@controller：控制层

@service：业务层

@repository：数据层

@component:普通的pojo注入到spring容器

 

组件注册方式：

 @componentscan  扫描那些要注入到spring容器的组件的包路径

package com.annotation.component;
import org.springframework.stereotype.controller;
import org.springframework.context.annotation.configuration;

@controller
public class personcontroller {

}

package com.annotation.register;
import org.springframework.context.annotation.componentscan;

//表明这是个注解配置类
@configuration  
@componentscan(value={"com.annotation.component"})
public class  config {
    
    
}


package com.annotation.register;
import org.springframework.context.annotation.annotationconfigapplicationcontext;
import com.annotation.component.controller.personcontroller;

public class test {
    public static void main(string[] args) {   
        annotationconfigapplicationcontext annotationconfigapplicationcontext = new annotationconfigapplicationcontext(config.class);
        personcontroller personcontroller = annotationconfigapplicationcontext.getbean(personcontroller.class);
    
    }
}

 @bean :主要作用在方法上，name可以指定bean在容器中的名称，不指定的话默认是方法名；initmethod指定bean的初始化方法；destroymethod指定bean的销毁方法

package com.annotation.component;

public class blue {

}


package com.annotation.register;

import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;
import com.annotation.component.bean.blue;

@configuration  
public class mainconfig {
    
    @bean(name="blue")
    public blue getcolor(){
        return new blue();
    }
    
}



package com.annotation.register;
import org.springframework.context.annotation.annotationconfigapplicationcontext;

import com.annotation.component.bean.blue;

public class test {
    public static void main(string[] args) {
        
        annotationconfigapplicationcontext annotationconfigapplicationcontext = new annotationconfigapplicationcontext(mainconfig.class);
        blue blue= annotationconfigapplicationcontext.getbean(blue.class);
        system.out.println(blue);
    
    }
}

 @import   :

• 注入一个bean
• 导入importselector的实现类，selectimports方法里面配置要注入的bean
• 导入importbeandefinitionregistrar的实现类，registerbeandefinitions方法里面配置要注入的bean

            

package com.annotation.component.bean;

public class blue {

}

package com.annotation.component.bean;

public class yellow {

}

package com.annotation.component.bean;

public class green{

}


package com.annotation.importbean;

import org.springframework.context.annotation.configuration;
import org.springframework.context.annotation.import;
import com.annotation.component.bean.white;

@configuration  
@import(value = { white.class,myimportselector.class,myimportbeandefinitionregistrar.class })
public class mainconfig {
    
    
}

package com.annotation.importbean;

import org.springframework.context.annotation.importselector;
import org.springframework.core.type.annotationmetadata;

public class myimportselector implements importselector{

    @override
    public string[] selectimports(annotationmetadata annotationmetadata) {
        return new string[]{"com.annotation.component.bean.yellow"};
    }

}

package com.annotation.importbean;

import org.springframework.beans.factory.support.beandefinitionregistry;
import org.springframework.beans.factory.support.rootbeandefinition;
import org.springframework.context.annotation.importbeandefinitionregistrar;
import org.springframework.core.type.annotationmetadata;

import com.annotation.component.bean.green;

public class myimportbeandefinitionregistrar implements importbeandefinitionregistrar{

    @override
    public void registerbeandefinitions(annotationmetadata annotationmetadata,
            beandefinitionregistry beandefinitionregistry) {
        rootbeandefinition beandefinition = new rootbeandefinition(green.class);
        beandefinitionregistry.registerbeandefinition("com.annotation.component.bean.green", beandefinition);
        
    }

}



package com.annotation.importbean;

import org.springframework.context.annotation.annotationconfigapplicationcontext;

public class test {
    public static void main(string[] args) {    
        annotationconfigapplicationcontext annotationconfigapplicationcontext = new annotationconfigapplicationcontext(mainconfig.class);
        string[] names = annotationconfigapplicationcontext.getbeandefinitionnames();
        for (string name : names) {
            system.out.println(name);
        }
        annotationconfigapplicationcontext.close();
        
    }
}

 implements factorybean

• getobject 方法表示要注入的对象，getobjecttype表示对象类型，issingleton表示是否单例
• annotationconfigapplicationcontext.getbean("colorfactorybean") 表示获取的是工程里面注入的对象，即color
• annotationconfigapplicationcontext.getbean("&colorfactorybean") 表示获取的是工程对象本身，即colorfactorybean

package com.annotation.component.bean;

public class color {

}



package com.annotation.factorybean;

import org.springframework.beans.factory.factorybean;

import com.annotation.component.bean.color;

public class colorfactorybean implements factorybean<color>{

    @override
    public color getobject() throws exception {
        return new color();
    }

    @override
    public class<?> getobjecttype() {
        return color.class;
    }

    @override
    public boolean issingleton() {
        return false;
    }

}


package com.annotation.factorybean;

import org.springframework.context.annotation.bean;
import org.springframework.context.annotation.configuration;

@configuration  
public class mainconfig {
    
    @bean
    public colorfactorybean colorfactorybean(){
        return new colorfactorybean();
    }
    
}


package com.annotation.factorybean;

import org.springframework.context.annotation.annotationconfigapplicationcontext;

public class test {
    public static void main(string[] args) {
        
        annotationconfigapplicationcontext annotationconfigapplicationcontext = new annotationconfigapplicationcontext(mainconfig.class);


        object obj1 = annotationconfigapplicationcontext.getbean("colorfactorybean");
        object obj2 = annotationconfigapplicationcontext.getbean("colorfactorybean");
        
        system.out.println(obj1==obj2);
        
        //获取factorybean 本身
        object obj3 = annotationconfigapplicationcontext.getbean("&colorfactorybean");
        system.out.println(obj3.getclass());
        annotationconfigapplicationcontext.close();
        
        
        
    }
}