Codeless的部落格

注入除了一般型態外,也可針對Collection(List、Map、Set、Properties)進行注入。

Customer.java

package com.example ;

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

 
public class Customer {

private List nameList ;
private Map nameMap ; 
private Set nameSet ; 
private Properties nameProp ;
public List getNameList() {
return nameList;
}
public void setNameList(List nameList) {
this.nameList = nameList;
}
public Map getNameMap() {
return nameMap;
}
public void setNameMap(Map nameMap) {
this.nameMap = nameMap;
}
public Set getNameSet() {
return nameSet;
}
public void setNameSet(Set nameSet) {
this.nameSet = nameSet;
}
public Properties getNameProp() {
return nameProp;
}
public void setNameProp(Properties nameProp) {
this.nameProp = nameProp;
}
}

Main.java

package com.example ;

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

public class Main {

public static void main(String[] args) {
ApplicationContext context = 
 new ClassPathXmlApplicationContext("Beans.xml");

Customer cust = (Customer) context.getBean("Customer");
System.out.println("name list:"+cust.getNameList()) ;
System.out.println("name map:"+cust.getNameMap()) ;
System.out.println("name set:"+cust.getNameSet()) ;
System.out.println("name property:"+cust.getNameProp()) ;
}
}

Map和Properties均屬於key-value paired,兩者差異在於Map key和value可以為任何物件型態,而Properties key和value只能為String型態。

Beans.xml

<bean id="Customer" class="com.example.Customer" >
 <!-- java.util.List -->
 <property name="nameList">
 <list>
 <value>Paul</value>
 <value>Alice</value>
 <value>Marry</value>
 </list>
 </property> 

 <!-- java.util.Map -->
 <property name="nameMap">
 <map>
 <entry key="1" value="Paul"/>
 <entry key="2" value="Alice"/>
 <entry key="3" value="Marry"/>
 <entry key="1" value="Paul"/>
 </map>
 </property>

 <!-- java.util.Set -->
 <property name="nameSet">
 <set>
 <value>Paul</value>
 <value>Alice</value>
 <value>Marry</value>
 <value>Paul</value>
 </set>
 </property> 

 <!-- java.util.Property -->
 <property name="nameProp">
 <props>
 <prop key="1">Paul</prop>
 <prop key="2">Alice</prop>
 <prop key="3">Marry</prop>
 <prop key="1">Paul</prop>
 </props>
 </property>

</bean>

結果顯示如下所示:

name list:[Paul, Alice, Marry]

name map:{1=Paul, 2=Alice, 3=Marry}

name set:[Paul, Alice, Marry]

name property:{3=Marry, 2=Alice, 1=Paul}

接著混合ref bean的情況如下所示:

CustomerRef.java

 
package com.example;

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

public class CustomerRef {

private List lists;
private Set sets;
private Map maps;
private Properties pros;

public List getLists() {
return lists;
}

public void setLists(List lists) {
this.lists = lists;
}

public Set getSets() {
return sets;
}

public void setSets(Set sets) {
this.sets = sets;
}

public Map getMaps() {
return maps;
}

public void setMaps(Map maps) {
this.maps = maps;
}

public Properties getPros() {
return pros;
}

public void setPros(Properties pros) {
this.pros = pros;
}

}

Person.java

package com.example;

public class Person {

String name;
String address;
int age;

public String getName() {
return name;
}

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

public String getAddress() {
return address;
}

public void setAddress(String address) {
this.address = address;
}

public int getAge() {
return age;
}

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

public String toString(){
return "name:"+name+",address:"+address+",age:"+age ;
}
}

MainRef.java

package com.example;

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

public class MainRef {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
"BeansRef.xml");

CustomerRef cust = (CustomerRef) context.getBean("CustomerBean");
System.out.println(cust.getLists());
System.out.println(cust.getMaps());
System.out.println(cust.getSets());
System.out.println(cust.getPros());
}
}

BeansRef.xml

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

 <!-- java.util.Set -->
 <property name="sets">
 <set>
 <value>1</value>
 <ref bean="PersonBean" />
 <bean class="com.example.Person">
 <property name="name" value="Steve" />
 <property name="address" value="American" />
 <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.example.Person">
 <property name="name" value="Steve" />
 <property name="address" value="American" />
 <property name="age" value="28" />
 </bean>
 </entry>
 </map>
 </property>

 <!-- java.util.Properties -->
 <property name="pros">
 <props>
 <prop key="1">Paul</prop>
 <prop key="2">Alice</prop>
 <prop key="3">Marry</prop>
 </props>
 </property>

</bean>

<bean id="PersonBean" class="com.example.Person">
 <property name="name" value="Paul" />
 <property name="address" value="Taipei" />
 <property name="age" value="31" />
</bean>

結果顯示如下所示: [1, name:Paul,address:Taipei,age:31, name:Steve,address:American,age:28]

{Key 1=1, Key 2=name:Paul,address:Taipei,age:31, Key 3=name:Steve,address:American,age:28}

[1, name:Paul,address:Taipei,age:31, name:Steve,address:American,age:28]

{3=Marry, 2=Alice, 1=Paul}

Injecting null and empty string values

等同於setName("") ;

<bean id="..." class="...">
 <property name="name" value=""/>
</bean>

等同於setName(null) ;

<bean id="..." class="...">
 <property name="name"><null/></property>
</bean>