Java依赖注入方式

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.wzh</groupId>
  <artifactId>Inject</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>Inject</name>
  <url>http://maven.apache.org</url>

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.source>1.8</maven.compiler.source>
    <maven.compiler.target>1.8</maven.compiler.target>
  </properties>

  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>3.8.1</version>
      <scope>test</scope>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-context-support -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-core</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>

    <!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-beans</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>

  </dependencies>
</project>

构造方法注入

application.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 = "Orange" class="com.wzh.fruit.impl.Orange"></bean>
    <bean id = "Apple" class="com.wzh.fruit.impl.Apple"></bean>

    <bean id = "personApple" class="com.wzh.person.Person">
        <constructor-arg ref="Apple"></constructor-arg>
    </bean>

    <bean id = "personOrange" class="com.wzh.person.Person">
        <constructor-arg ref="Orange"></constructor-arg>
    </bean>

</beans>

Fruit.java

package com.wzh.fruit;

public interface Fruit {
    public String getFruit();
}

Apple.java

package com.wzh.fruit.impl;

import com.wzh.fruit.Fruit;

public class Apple implements Fruit{

    public Apple() {

    }

    public String getFruit() {
        String apple = "apple";
        return apple;
    }

}

Orange.java

package com.wzh.fruit.impl;

import com.wzh.fruit.Fruit;

public class Orange implements Fruit{

    public Orange() {

    }

    public String getFruit() {
        String orange = "orange";
        return orange;
    }

}

Person.java

package com.wzh.person;

import java.lang.reflect.Constructor;

import com.wzh.fruit.Fruit;

public class Person {

    private Fruit fruit;

    public Person(Fruit _fruit) {
        fruit = _fruit;
    }

    public void eat() {
        System.out.println("I want eat "+fruit.getFruit());
    }

}

Run.java

package com.wzh.run;

import com.wzh.person.Person;

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

public class Run {

    public static void main(String[] args) {
        ApplicationContext ac=new ClassPathXmlApplicationContext("application.xml");
        Person p =(Person)ac.getBean("personOrange");
        p.eat();
    }

}

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

setter注入

application.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 = "Orange" class="com.wzh.fruit.impl.Orange"></bean>
    <bean id = "Apple" class="com.wzh.fruit.impl.Apple"></bean>
    <bean id = "Watermelon" class="com.wzh.fruit.impl.Watermelon"></bean>

    <bean id = "personApple" class="com.wzh.person.Person">
        <property name="Fruit" ref="Apple"></property>
    </bean>

    <bean id = "personOrange" class="com.wzh.person.Person">
        <property name="Fruit" ref="Orange"></property>
    </bean>

    <bean id = "personWatermelon" class="com.wzh.person.Person">
        <property name="Fruit" ref="Watermelon"></property>
    </bean>

</beans>

Person.java

package com.wzh.person;

import java.lang.reflect.Constructor;

import com.wzh.fruit.Fruit;

public class Person {

    private Fruit fruit;

    public void setFruit(Fruit _fruit) {
        fruit = _fruit;
    }

    public void eat() {
        System.out.println("I want eat "+fruit.getFruit());
    }

}

Run.java

package com.wzh.run;

import com.wzh.person.Person;

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

public class Run {

    public static void main(String[] args) {
        ApplicationContext ac=new ClassPathXmlApplicationContext("application.xml");
        Person p =(Person)ac.getBean("personWatermelon");
        p.eat();
    }

}

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

注解

application.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:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">

    <context:annotation-config />
    <context:component-scan base-package="com.wzh.*">
    </context:component-scan>

</beans>

Apple.java

package com.wzh.fruit.impl;

import org.springframework.stereotype.Component;

import com.wzh.fruit.Fruit;

@Component("Apple")
public class Apple implements Fruit{

    public String getFruit() {
        String apple = "apple";
        return apple;
    }

}

Orange.java

package com.wzh.fruit.impl;

import org.springframework.stereotype.Component;

import com.wzh.fruit.Fruit;

@Component("Orange")
public class Orange implements Fruit{

    public String getFruit() {
        String orange = "orange";
        return orange;
    }

}

Person.java

package com.wzh.person;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;

import com.wzh.fruit.Fruit;

@Component("Person")
public class Person {

    @Autowired
    @Qualifier("Apple")
    private Fruit fruit;

    public void eat() {
        System.out.println("I want eat "+fruit.getFruit());
    }

}

Run.java

package com.wzh.run;

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

import com.wzh.person.Person;

public class Run {

    public static void main(String[] args) {

        ApplicationContext ac=new ClassPathXmlApplicationContext("application.xml");
        Person p =(Person)ac.getBean("Person");
        p.eat();
    }

}