Preface

What is IOC? IOC is inversion of control. For example, you originally created a new turkey yourself, but now let the control power to spring, which uses dependency injection technology to do it for you.

One, IOC-setter injection

1. Prepare dmo

First prepare a turkey

public class Turkey {
    private int id;
    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

Then prepare a kitchen, the property contains turkey

public class Cookhouse {
    private int id;
    private String name;
    private Turkey turkey;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Turkey getTurkey() {
        return turkey;
    }

    public void setTurkey(Turkey turkey) {
        this.turkey = turkey;
    }

    @Override
    public String toString() {
        return "Cookhouse{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

2. ApplicationContext.xml configuration

Give the bean a name, class is the dmo class, property name is the property name, value and ref are the property values,If the attribute is an object, use "ref="

<?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:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
   http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <bean name="t" class="Turkey">
        <property name="name" value="usaTurkey"/>
    </bean>

    <bean name="c" class="Cookhouse">
        <property name="name" value="cnCookhouse"/>
        <property name="turkey" ref="t"/>
    </bean>
</beans>

3. Add spring related JAR packages

JAR package and other knowledge are detailed in a project of a great god on the Internet:Self-study website

4. Spring helps us make turkey in the kitchen

Let spring help me cook turkey in the kitchen. Spring created a Chinese kitchen based on the core configuration file applicationContext.xml, and then made an American turkey.

public class TestSpring {
    public static void main(String[] args) {
        ClassPathXmlApplicationContext applicationContext = new ClassPathXmlApplicationContext(new String[]{"applicationContext.xml"});
        Cookhouse c = (Cookhouse)applicationContext.getBean("c");
        System.out.println(c.getName()+"Done only"+c.getTurkey().getName());
    }
}

operation result:

Two, IOC-annotation injection

Some friends said: turkey cooking is too slow, waiting for hungry
spring said: Then I will use annotation injection to make turkey for you

1. @Autowired's annotations on attributes

First optimize the injection method of the object, add applicationContext.xml<context:annotation-config/>, Which tells Spring to use annotations for injection,<property name="turkey" ref="t"/>It can be commented out, we only need to add @Autowired to the attribute Turkey of the Cookhouse class to inject the turkey

@Autowired
    private Turkey turkey;

2. @Component's annotation on Bean

Then optimize the Bean injection method. Bean injection in applicationContext.xml still looks cumbersome. Let’s simplify it and add only:

<context:component-scan base-package="com.fantasy.dmo"/>
Its function is to tell Spring that all beans are placed in this package

<?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:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:context="http://www.springframework.org/schema/context"
       xsi:schemaLocation="
   http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <!--beans are placed under this package-->
    <context:component-scan base-package="com.fantasy.dmo"/>
</beans>

Because Bean has moved to dmo, annotate @Component to Cookhouse and Turkey in dmo, and then name their properties.

@Component("c")
public class Cookhouse {
    private int id;
    private String name="cnCookhouse";
    @Autowired
    private Turkey turkey;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

    public Turkey getTurkey() {
        return turkey;
    }

    public void setTurkey(Turkey turkey) {
        this.turkey = turkey;
    }

    @Override
    public String toString() {
        return "com.fantasy.dmo.Cookhouse{" +
                "id=" + id +
                ", name='" + name + '\'' +
                '}';
    }
}

@Component("t")
public class Turkey {
    private int id;
    private String name="usaTurkey";

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

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

The result of running the program is the same, and a lot of configuration is omitted. The fragrant turkey can be made faster~