Spring Dependency Injection 简明教程
Spring DI - Map Ref Setter
您已经看到如何使用 Bean 配置文件中的 <property> 标记的 value 属性配置原始数据类型，以及使用 ref 属性配置对象引用。这两种情况都涉及将奇异值传递给 Bean。
现在，如果你想传递 Map，该怎么办？在本示例中，我们展示使用 setter 注入传递 Map 的直接值。
Example
以下示例展示了一个类 JavaCollection，该类使用集合作为依赖关系，并使用 setter 方法进行注入。
让我们更新在 Spring DI - Create Project 章节中创建的项目。我们将添加以下文件 −
-
Address.java - 用于作为依赖项的类。
-
JavaCollection.java - 包含依赖项集合的类。
-
MainApp.java - 要运行和测试的主应用。
以下是 Address.java 文件的内容 −
package com.tutorialspoint;
public class Address {
private String name;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return name;
}
}以下是 JavaCollection.java 文件的内容−
package com.tutorialspoint;
import java.util.*;
public class JavaCollection {
Map<String, Address> addressMap;
public JavaCollection() {}
public JavaCollection(Map<String, Address> addressMap) {
this.addressMap = addressMap;
}
// a setter method to set Map
public void setAddressMap(Map<String, Address> addressMap) {
this.addressMap = addressMap;
}
// prints and returns all the elements of the Map.
public Map<String, Address> getAddressMap() {
System.out.println("Map Elements :" + addressMap);
return addressMap;
}
}以下是 MainApp.java 文件的内容−
package com.tutorialspoint;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext("applicationcontext.xml");
JavaCollection jc=(JavaCollection)context.getBean("javaCollection");
jc.getAddressMap();
}
}以下是配置文件 applicationcontext.xml ，其中包含了所有类型的集合配置 −
<?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-3.0.xsd">
<bean id = "address1" class = "com.tutorialspoint.Address">
<property name="name" value="INDIA"></property>
</bean>
<bean id = "address2" class = "com.tutorialspoint.Address">
<property name="name" value="JAPAN"></property>
</bean>
<bean id = "address3" class = "com.tutorialspoint.Address">
<property name="name" value="USA"></property>
</bean>
<bean id = "address4" class = "com.tutorialspoint.Address">
<property name="name" value="UK"></property>
</bean>
<bean id = "javaCollection" class = "com.tutorialspoint.JavaCollection">
<property name = "addressMap">
<map>
<entry key = "1" value-ref = "address1"/>
<entry key = "2" value-ref = "address2"/>
<entry key = "3" value-ref = "address3"/>
<entry key = "4" value-ref = "address4"/>
</map>
</property>
</bean>
</beans>