IOC operations – Bean managed dependency injection (DI) – BASED on XML

1. The first injection method: injection with a parameter constructor

Example:

    User：
    public class User {
    private String name;
    private String sex;
    public User()
    {
        System.out.println("I'm a no-argument constructor for User.");
    }
    public User(String name,String sex)
    {
        this.name=name;
        this.sex=sex;
        System.out.println("I'm a two-parameter constructor for User.");
    }
    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\' ' +
                ", sex='" + sex + '\' ' +
                '} ';
    }
}
bean1.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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="user" class="com.zcy.www.entity.User" >
        <constructor-arg name="sex" value="Male"></constructor-arg>
        <constructor-arg name="name" value="Late Breeze"></constructor-arg>
    </bean>
</beans>Test: @ Test publicvoid test()
    {
        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("bean1.xml");
        User user = applicationContext.getBean("user", User.class);
        System.out.println(user);
    }
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2. The second injection mode is SET injection

Example:

Bean. 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"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="user" class="com.zcy.www.entity.User" >
        <property name="name" value="Late Breeze"></property>
        <property name="sex>" value="Male"></property>
    </bean>
</beans>
User：
public class User {
    private String name;
    private String sex;
    public void setName(String name) {
        this.name = name;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "User{" +
                "name='" + name + '\' ' +
                ", sex='" + sex + '\' ' +
                '} '; }}Copy the code

3. The third type of injection: P namespace injection (simplified SET injection)

Example:

bean.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="user" class="com.zcy.www.entity.User" p:name="Late Breeze" p:sex="Male">
    </bean>
</beans>
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