Spring入门第三课

时间：2017-05-18 23:08:21 阅读：329 评论：0 收藏：0 [点我收藏+]

标签：res rom setter 名称注入属性 ring utf-8 字符应用程序

属性注入

属性注入就是通过setter方法注入Bean的属性值或依赖的对象。

属性植入使用<property>元素，使用name属性指定Bean的属性名称，value属性或者<value>子节点指定属性值

属性注入是实际应用中最常用的注入方式。

构造方法注入

通过构造方法注入Bean的属性值或依赖的对象，它保证了Bean实例化以后就可以使用。

构造器注入在<constructor-arg>元素里申明属性，<constructor-arg>中没有name属性

package logan.spring.study;

public class Car {
    private String brand;
    private String corp;
    private int price;
    private int maxspeed;
    public Car(String brand, String corp, int price) {
        super();
        this.brand = brand;
        this.corp = corp;
        this.price = price;
    }
    @Override
    public String toString() {
        return "Car [brand=" + brand + ", corp=" + corp + ", price=" + price + ", maxspeed=" + maxspeed + "]";
    }
}

package logan.spring.study;

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

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.创建Spring的IOC容器对象
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从 IOC容器中获取Bean实例
        HelloWorld helloWorld = (HelloWorld) ctx.getBean("hello");
        //HelloWorld hello = ctx.getBean(HelloWorld.class);
        //3.调用hello方法
        //System.out.println(hello);
        
        Car car = ctx.getBean(Car.class);
        System.out.println(car);

    }

}

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi"></constructor-arg>
        <constructor-arg value="Shanghai"></constructor-arg>
        <constructor-arg value="3000000"></constructor-arg>
    </bean>

</beans>

还可以这样配置

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2"></constructor-arg>
    </bean>

</beans>

当如下配置时，会不合逻辑

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma"></constructor-arg>
        <constructor-arg value="Shanghai"></constructor-arg>
        <constructor-arg value="240"></constructor-arg>
    </bean>

</beans>

package logan.spring.study;

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

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.创建Spring的IOC容器对象
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从 IOC容器中获取Bean实例
        HelloWorld helloWorld = (HelloWorld) ctx.getBean("hello");
        //HelloWorld hello = ctx.getBean(HelloWorld.class);
        //3.调用hello方法
        //System.out.println(hello);
        
        Car car = (Car) ctx.getBean("car");
        System.out.println(car);
        Car car2 = (Car) ctx.getBean("car2");
        System.out.println(car2);

    }

}

这个是得到的结果

五月 18, 2017 10:00:14 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3eb07fd3: startup date [Thu May 18 22:00:14 CST 2017]; root of context hierarchy
五月 18, 2017 10:00:14 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
HelloWorld‘s Constructor...
HelloWorld‘s Constructor...
Car [brand=Audi, corp=Shanghai, price=3000000.0, maxspeed=0]
Car [brand=Baoma, corp=Shanghai, price=240.0, maxspeed=0]

可以看到240没有赋值到maxSpeed上。

如下修改配置文件可以正确赋值

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2" type="double"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
        <constructor-arg value="Shanghai" type="java.lang.String"></constructor-arg>
        <constructor-arg value="240" type="int"></constructor-arg>
    </bean>

</beans>

得到如下结果：使用构造器注入属性值时可以指定参数的位置和参数的类型！以区分重载的构造器

五月 18, 2017 10:04:26 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3eb07fd3: startup date [Thu May 18 22:04:26 CST 2017]; root of context hierarchy
五月 18, 2017 10:04:26 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
HelloWorld‘s Constructor...
HelloWorld‘s Constructor...
Car [brand=Audi, corp=Shanghai, price=3000000.0, maxspeed=0]
Car [brand=Baoma, corp=Shanghai, price=0.0, maxspeed=240]

还可以如下配置，使用子节点给属性赋值

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2" type="double"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
        <constructor-arg value="Shanghai" type="java.lang.String"></constructor-arg>
        <constructor-arg type="int">
            <value>250</value>
        </constructor-arg>
    </bean>

</beans>

字面值：可以使用字符串表示的值，可以通过<value>元素标签或者value属性进行注入。

基本数据类型及其封装类，String等类型都可以采取字面值注入的方式

若字面值中包含特殊字符，可以使用<![CDATA[]]>把字面值包裹起来。

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2" type="double"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
        <constructor-arg type="java.lang.String">
            <value><![CDATA[<Shanghai>]]></value>
        </constructor-arg>
        <constructor-arg type="int">
            <value>250</value>
        </constructor-arg>
    </bean>

</beans>

下面看Bean相互引用

组成应用程序的Bean经常需要相互协作以完成应用程序的功能。要使Bean能够相互访问，就必须在Bean配置文件中指定对Bean的引用。

在Bean的配置文件中，可以通过<ref>元素或者ref属性为Bean的属性或者构造器参数指定对Bean的引用。

也可以在属性或者构造器里包含Bean的声明，这样的Bean称为内部Bean。

package logan.spring.study;

public class Person {
    
    private String name;
    
    private int age;
    
    private Car car;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Car getCar() {
        return car;
    }

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

    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", car=" + car + "]";
    }
}

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2" type="double"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
        <constructor-arg type="java.lang.String">
            <value><![CDATA[<Shanghai>]]></value>
        </constructor-arg>
        <constructor-arg type="int">
            <value>250</value>
        </constructor-arg>
    </bean>
    
    <bean id="person" class="logan.spring.study.Person">
        <property name="name" value="Tom"></property>
        <property name="age" value="24"></property>
        <property name="car" ref="car2"></property>
    </bean>

</beans>

package logan.spring.study;

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

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.创建Spring的IOC容器对象
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从 IOC容器中获取Bean实例
        HelloWorld helloWorld = (HelloWorld) ctx.getBean("hello");
        //HelloWorld hello = ctx.getBean(HelloWorld.class);
        //3.调用hello方法
        //System.out.println(hello);
        
        Car car = (Car) ctx.getBean("car");
        System.out.println(car);
        Car car2 = (Car) ctx.getBean("car2");
        System.out.println(car2);
        Person person = ctx.getBean(Person.class);
        System.out.println(person);
    }

}

下面是输出结果

五月 18, 2017 10:21:47 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3eb07fd3: startup date [Thu May 18 22:21:47 CST 2017]; root of context hierarchy
五月 18, 2017 10:21:47 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
HelloWorld‘s Constructor...
HelloWorld‘s Constructor...
Car [brand=Audi, corp=Shanghai, price=3000000.0, maxspeed=0]
Car [brand=Baoma, corp=<Shanghai>, price=0.0, maxspeed=250]
Person [name=Tom, age=24, car=Car [brand=Baoma, corp=<Shanghai>, price=0.0, maxspeed=250]]

看内部Bean配置方法：

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2" type="double"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
        <constructor-arg type="java.lang.String">
            <value><![CDATA[<Shanghai>]]></value>
        </constructor-arg>
        <constructor-arg type="int">
            <value>250</value>
        </constructor-arg>
    </bean>
    
    <bean id="person" class="logan.spring.study.Person">
        <property name="name" value="Tom"></property>
        <property name="age" value="24"></property>
        <property name="car">
            <bean class="logan.spring.study.Car">
                <constructor-arg value="Ford"></constructor-arg>
                <constructor-arg value="Changan"></constructor-arg>
                <constructor-arg value="20000000" type="double"></constructor-arg>
            </bean>
        </property>
    </bean>

</beans>

运行结果

五月 18, 2017 10:36:26 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3eb07fd3: startup date [Thu May 18 22:36:26 CST 2017]; root of context hierarchy
五月 18, 2017 10:36:26 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
HelloWorld‘s Constructor...
HelloWorld‘s Constructor...
Car [brand=Audi, corp=Shanghai, price=3000000.0, maxspeed=0]
Car [brand=Baoma, corp=<Shanghai>, price=0.0, maxspeed=250]
Person [name=Tom, age=24, car=Car [brand=Ford, corp=Changan, price=2.0E7, maxspeed=0]]

注意：内部Bean不能被外部Bean引用。

还可以如下配置

<?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">
    
    <!-- 配置bean
    class:bean的全类名，通过反射的方式在IOC容器中创建bean，所以要求Bean中必须有无参的构造函数
    id:表示容器的bean，id唯一 -->
    <bean id="hello" class="logan.spring.study.HelloWorld">
    </bean>
    
    <bean id="hello2" class="logan.spring.study.HelloWorld">
    </bean>
    
    <!-- 通过构造方法来配置Bean的属性 -->
    <bean id="car" class="logan.spring.study.Car">
        <constructor-arg value="Audi" index="0"></constructor-arg>
        <constructor-arg value="Shanghai" index="1"></constructor-arg>
        <constructor-arg value="3000000" index="2" type="double"></constructor-arg>
    </bean>
    <bean id="car2" class="logan.spring.study.Car">
        <constructor-arg value="Baoma" type="java.lang.String"></constructor-arg>
        <constructor-arg type="java.lang.String">
            <value><![CDATA[<Shanghai>]]></value>
        </constructor-arg>
        <constructor-arg type="int">
            <value>250</value>
        </constructor-arg>
    </bean>
    
    <bean id="person" class="logan.spring.study.Person">
        <property name="name" value="Tom"></property>
        <property name="age" value="24"></property>
        <property name="car">
            <bean class="logan.spring.study.Car">
                <constructor-arg value="Ford"></constructor-arg>
                <constructor-arg value="Changan"></constructor-arg>
                <constructor-arg value="20000000" type="double"></constructor-arg>
            </bean>
        </property>
    </bean>
    
    <bean id="person2" class="logan.spring.study.Person">
        <constructor-arg value="Jerry"></constructor-arg>
        <constructor-arg value="25"></constructor-arg>
        <constructor-arg ref="car"></constructor-arg>
    </bean>

</beans>

package logan.spring.study;

public class Person {
    
    private String name;
    
    private int age;
    
    private Car car;

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public Car getCar() {
        return car;
    }

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

    @Override
    public String toString() {
        return "Person [name=" + name + ", age=" + age + ", car=" + car + "]";
    }
    
    public Person() {
        // TODO Auto-generated constructor stub
    }

    public Person(String name, int age, Car car) {
        super();
        this.name = name;
        this.age = age;
        this.car = car;
    }
    
    
}

package logan.spring.study;

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

public class Main {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //1.创建Spring的IOC容器对象
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        //2.从 IOC容器中获取Bean实例
        HelloWorld helloWorld = (HelloWorld) ctx.getBean("hello");
        //HelloWorld hello = ctx.getBean(HelloWorld.class);
        //3.调用hello方法
        //System.out.println(hello);
        
        Car car = (Car) ctx.getBean("car");
        System.out.println(car);
        Car car2 = (Car) ctx.getBean("car2");
        System.out.println(car2);
        Person person = (Person) ctx.getBean("person2");
        System.out.println(person);
        

    }

}

输出结果如下：

五月 18, 2017 10:43:51 下午 org.springframework.context.support.ClassPathXmlApplicationContext prepareRefresh
信息: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@3eb07fd3: startup date [Thu May 18 22:43:51 CST 2017]; root of context hierarchy
五月 18, 2017 10:43:51 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
信息: Loading XML bean definitions from class path resource [applicationContext.xml]
HelloWorld‘s Constructor...
HelloWorld‘s Constructor...
Car [brand=Audi, corp=Shanghai, price=3000000.0, maxspeed=0]
Car [brand=Baoma, corp=<Shanghai>, price=0.0, maxspeed=250]
Person [name=Jerry, age=25, car=Car [brand=Audi, corp=Shanghai, price=3000000.0, maxspeed=0]]

Spring入门第三课

标签：res rom setter 名称注入属性 ring utf-8 字符应用程序

原文地址：http://www.cnblogs.com/LoganChen/p/6876007.html

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