【Spring】Bean 自动装配

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自动装配

byName

byName 根据 bean 的名字和当前 bean 的 setter 风格的属性名进行自动装配，若有匹配的，则进行自动装配，若没有匹配的，则不装配。

<bean id="address" class="com.test.sping.beans.autowire.Address"
        p:city="BeiJing" p:street="HuiLongGuan"></bean>

    <bean id="car" class="com.test.sping.beans.autowire.Car"
        p:brand="Audi" p:price="300000"></bean>

    <!-- 可以使用 autowire 属性指定自动装配的方式 -->
    <bean id="person" class="com.test.sping.beans.autowire.Person"
        p:name="Tom" autowire="byName"></bean>

byType

byType 根据 bean 的类型和当前 bean 的属性的类型进行自动装配，若 IOC 容器中 1 个以上的类型匹配的 bean，则抛异常。

<bean id="address" class="com.test.sping.beans.autowire.Address"
        p:city="BeiJing" p:street="HuiLongGuan"></bean>

    <bean id="car" class="com.test.sping.beans.autowire.Car"
        p:brand="Audi" p:price="300000"></bean>

    <!-- 可以使用 autowire 属性指定自动装配的方式 -->
    <bean id="person" class="com.test.sping.beans.autowire.Person"
        p:name="Tom" autowire="byType"></bean>

源码

Address.java(com.test.sping.beans.autowire.Address)

package com.test.sping.beans.autowire;

public class Address {

    private String city;
    private String street;

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getStreet() {
        return street;
    }

    public void setStreet(String street) {
        this.street = street;
    }

    @Override
    public String toString() {
        return "Address{" +
                "city='" + city + '\'' +
                ", street='" + street + '\'' +
                '}';
    }
}

Car.java(com.test.sping.beans.autowire.Car)

package com.test.sping.beans.autowire;

public class Car {

    private String brand;
    private double price;

    public String getBrand() {
        return brand;
    }

    public void setBrand(String brand) {
        this.brand = brand;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
        return "Car{" +
                "brand='" + brand + '\'' +
                ", price=" + price +
                '}';
    }

    public Car() {
        System.out.println("Car's Constructor...");
    }
}

Person.java(com.test.sping.beans.autowire.Person)

package com.test.sping.beans.autowire;


public class Person {

    private String name;

    private Address address;

    private Car car;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Address getAddress() {
        return address;
    }

    public void setAddress(Address address) {
        this.address = address;
    }

    public Car getCar() {
        return car;
    }

    public void setCar(Car car) {
        this.car = car;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", address=" + address +
                ", car=" + car +
                '}';
    }
}

Main.java(com.test.sping.beans.autowire.Main)

package com.test.sping.beans.autowire;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {

    public static void main(String[] args) {

        ApplicationContext ctx = new ClassPathXmlApplicationContext("beans-autowire.xml");
        Person person = (Person) ctx.getBean("person");

        System.out.println(person);

    }

}

beans-autowire.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="address" class="com.test.sping.beans.autowire.Address"
        p:city="BeiJing" p:street="HuiLongGuan"></bean>

    <bean id="car" class="com.test.sping.beans.autowire.Car"
        p:brand="Audi" p:price="300000"></bean>

    <!--
        可以使用 autowire 属性指定自动装配的方式：
        byName 根据 bean 的名字和当前 bean 的 setter 风格的属性名进行自动装配，若有匹配的，则进行自动装配，若没有匹配的，则不装配。
        byType 根据 bean 的类型和当前 bean 的属性的类型进行自动装配，若 IOC 容器中 1 个以上的类型匹配的 bean，则抛异常。
    -->
    <bean id="person" class="com.test.sping.beans.autowire.Person"
        p:name="Tom" autowire="byName"></bean>

</beans>