2015-03-03

[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]
    ]
]

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