Spring中三种注入方式

spring 学习

目录

1. 构造器注入
2. 工厂方法注入
3. setter注入

1.构造器注入

xml:

<bean id="duke" class="cesar.test.spring.bean.Judgler">
        <constructor-arg value="15"></constructor-arg>
    </bean>

java:

public class Judgler implements Performer{
    private int beanBags = 3;
    public Judgler(){
    }
    Judgler(int beanBags){
        this.beanBags = beanBags;
    }
    @Override
    public void perform() {
        System.out.println("JUGGLING "+ beanBags+" BEANBAGS");
    }
}

2.setter注入

java文件:

package cesar.test.spring.bean;
import cesar.test.spring.Instrument;
public class Instrumentalist implements Performer {
    public Instrumentalist() {
    }
    private String song;
    private Instrument instrument;
    public void setSong(String song) {
        this.song = song;
    }
    public String getSong() {
        return song;
    }
    @Override
    public void perform() {
        System.out.println("playing"+song+":");
        instrument.play();
    }
    public Instrument getInstrument() {
        return instrument;
    }
    public void setInstrument(Instrument instrument) {
        this.instrument = instrument;
    }
}

2.1 注入简单值

• 使用property关键字配合value

<bean id="instru" class="cesar.test.spring.bean.Instrumentalist">
    <property name="song" value="我恨我爱你"></property>
    </bean>

2.2 注入其他bean

• 使用property关键字配合ref

<bean id="instru" class="cesar.test.spring.bean.Instrumentalist">
    <property name="song" value="我恨我爱你"></property>
    <property name="instrument" ref=""></property>
    </bean>

3.工厂方法注入

xml:

<bean id="theStage" class="cesar.test.spring.bean.Stage"
        factory-method="getInstance">
    </bean>

java:

public class Stage {
    private Stage(){}
    private static class StageSingletonHolder{
        static Stage instance = new Stage();
    }
    public static Stage getInstance(){
        return StageSingletonHolder.instance;
    }
    public void sayHello() {
        System.out.println("Hello");
    }
}