[轉載] Spring Collections (List, Set, Map, and Properties)

轉載自：Spring Collections (List, Set, Map, and Properties) example

Spring examples to show you how to inject values into collections type (List, Set, Map, and Properties). 4 major collection types are supported :

• List – <list/>
• Set – <set/>
• Map – <map/>
• Properties – <props/>

Spring beans

A Customer object, with four collection properties.

package com.mkyong.common;

import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class Customer
{
    private List<Object> lists;
    private Set<Object> sets;
    private Map<Object, Object> maps;
    private Properties pros;

    //...
}

See different code snippets to declare collection in bean configuration file.

1. List example

<property name="lists">
    <list>
        <value>1</value>
        <ref bean="PersonBean" />
        <bean class="com.mkyong.common.Person">
            <property name="name" value="mkyongList" />
            <property name="address" value="address" />
            <property name="age" value="28" />
        </bean>
    </list>
</property>

2. Set example

<property name="sets">
    <set>
        <value>1</value>
        <ref bean="PersonBean" />
        <bean class="com.mkyong.common.Person">
            <property name="name" value="mkyongSet" />
            <property name="address" value="address" />
            <property name="age" value="28" />
        </bean>
    </set>
</property>

3. Map example

<property name="maps">
    <map>
        <entry key="Key 1" value="1" />
        <entry key="Key 2" value-ref="PersonBean" />
        <entry key="Key 3">
            <bean class="com.mkyong.common.Person">
                <property name="name" value="mkyongMap" />
                <property name="address" value="address" />
                <property name="age" value="28" />
            </bean>
        </entry>
    </map>
</property>

4. Properties example

<property name="pros">
    <props>
        <prop key="admin">admin@nospam.com</prop>
        <prop key="support">support@nospam.com</prop>
    </props>
</property>

Full Spring’s bean configuration file.

<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-2.5.xsd">

    <bean id="CustomerBean" class="com.mkyong.common.Customer">

        <!-- java.util.List -->
        <property name="lists">
            <list>
                <value>1</value>
                <ref bean="PersonBean" />
                <bean class="com.mkyong.common.Person">
                    <property name="name" value="mkyongList" />
                    <property name="address" value="address" />
                    <property name="age" value="28" />
                </bean>
            </list>
        </property>

        <!-- java.util.Set -->
        <property name="sets">
            <set>
                <value>1</value>
                <ref bean="PersonBean" />
                <bean class="com.mkyong.common.Person">
                    <property name="name" value="mkyongSet" />
                    <property name="address" value="address" />
                    <property name="age" value="28" />
                </bean>
            </set>
        </property>

        <!-- java.util.Map -->
        <property name="maps">
            <map>
                <entry key="Key 1" value="1" />
                <entry key="Key 2" value-ref="PersonBean" />
                <entry key="Key 3">
                    <bean class="com.mkyong.common.Person">
                        <property name="name" value="mkyongMap" />
                        <property name="address" value="address" />
                        <property name="age" value="28" />
                    </bean>
                </entry>
            </map>
        </property>

        <!-- java.util.Properties -->
        <property name="pros">
            <props>
                <prop key="admin">admin@nospam.com</prop>
                <prop key="support">support@nospam.com</prop>
            </props>
        </property>

    </bean>

    <bean id="PersonBean" class="com.mkyong.common.Person">
        <property name="name" value="mkyong1" />
        <property name="address" value="address 1" />
        <property name="age" value="28" />
    </bean>
</beans>

Run it…

package com.mkyong.common;

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

public class App {

    public static void main( String[] args ) {

        ApplicationContext context 
            = new ClassPathXmlApplicationContext("SpringBeans.xml");

        Customer cust = (Customer)context.getBean("CustomerBean");
        System.out.println(cust);
    }
}

Output

Customer [
    lists=[
        1,
        Person [address=address 1, age=28, name=mkyong1],
        Person [address=address, age=28, name=mkyongList]
    ],

    maps={
        key 1=1,
        key 2=Person [address=address 1, age=28, name=mkyong1],
        key 3=Person [address=address, age=28, name=mkyongMap]
    },

    pros={
        admin=admin@nospam.com,
        support=support@nospam.com
    },

    sets=[
        1,
        Person [address=address 1, age=28, name=mkyong1],
        Person [address=address, age=28, name=mkyongSet]
    ]
]