Bean的裝配方式-基於XML的裝配

1.設值注入

使用該方法時Bean類必須要有一個無參構造方法，並且Bean類必須爲屬性提供setter方法

在配置文件中，使用<property>元素來爲每個屬性注入值。

Bean類示例代碼如下：

package com.assemble;

import java.util.List;

public class User {
	private String username;
	private String password;
	private List<String> list;
	
	public User(String username, String password, List<String> list) {
		super();
		this.username = username;
		this.password = password;
		this.list = list;
	}

	public User() {
		super();
	}


	public void setUsername(String username) {
		this.username = username;
	}


	public void setPassword(String password) {
		this.password = password;
	}


	public void setList(List<String> list) {
		this.list = list;
	}

	@Override
	public String toString() {
		return "User [username=" + username + ", password=" + password + ", list=" + list + "]";
	}
	
	
	
}

 XML配置文件代碼示例如下：

<?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">
	<!-- 2.使用設值注入方式裝配User實例 -->
	<bean id="user2" class="com.assemble.User">
		<property name="username" value="張三"></property>
		<property name="password" value="123456"></property>
		<property name="list">
			<list>
				<value>"setlistvalue01"</value>
				<value>"setlistvalue02"</value>
			</list>
		</property>
	</bean>
</beans>

2.構造注入

使用該方法Bean類必須提供有參構造方法，配置文件中使用<constructor-arg>元素來爲參數注入值。

XML配置文件代碼示例如下：

<?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">
    <!-- 1.使用構造注入方式裝配User實例 -->
	<bean id="user1" class="com.assemble.User">
		<constructor-arg index="0" value="tom"></constructor-arg>
		<constructor-arg name="password" value="123456"></constructor-arg>
		<constructor-arg name="list">
			<list>
				<value>"constructorvalue01"</value>
				<value>"constructorvalue02"</value>
			</list>
		</constructor-arg>
	</bean>
</beans>

測試是否注入成功： 

package com.assemble;

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

public class XmlBeanAssembleTest {
	public static void main(String[] args) {
		//定義配置文件路徑
		String xmlPath = "com/assemble/bean5.xml";
		//ClassPathXmlApplicationContext在加載配置文件時，對Bean進行實例化
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext(xmlPath);
		System.out.println(applicationContext.getBean("user1"));
		System.out.println(applicationContext.getBean("user2"));
	}

}

運行結果：

 成功裝配。