Spring中為bean注入Date對象

比如我們有下面的一個bean：

import java.util.Date;
 
public class Customer {
 
	Date date;
 
	public Date getDate() {
		return date;
	}
 
	public void setDate(Date date) {
		this.date = date;
	}
 
	@Override
	public String toString() {
		return "Customer [date=" + date + "]";
	}
 
}

　　注意我們上面的bean中有一個Date，但是如果我們使用下面的配置：

<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="customer" class="com.mkyong.common.Customer">
		<property name="date" value="2010-01-31" />
	</bean>
 
</beans>

　　然后我們嘗試着運行的話

public class App {
	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext(
				"SpringBeans.xml");
 
		Customer cust = (Customer) context.getBean("customer");
		System.out.println(cust);
 
	}
}

會出現如下的錯誤：

Caused by: org.springframework.beans.TypeMismatchException: 
	Failed to convert property value of type [java.lang.String] to 
	required type [java.util.Date] for property 'date'; 
 
nested exception is java.lang.IllegalArgumentException: 
	Cannot convert value of type [java.lang.String] to
	required type [java.util.Date] for property 'date': 
	no matching editors or conversion strategy foun
在這里提供兩種解決辦法：

1. Factory bean

聲明一個dateFormat的bean，然后引用。如下解決：

<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="dateFormat" class="java.text.SimpleDateFormat">
		<constructor-arg value="yyyy-MM-dd" />
	</bean>
 
	<bean id="customer" class="com.mkyong.common.Customer">
		<property name="date">
			<bean factory-bean="dateFormat" factory-method="parse">
				<constructor-arg value="2010-01-31" />
			</bean>
		</property>
	</bean>
 
</beans>

　　

2. CustomDateEditor

我們聲明一個CustomDateEditor，將String轉換為Date對象。

<bean id="dateEditor"
	   class="org.springframework.beans.propertyeditors.CustomDateEditor">
 
		<constructor-arg>
			<bean class="java.text.SimpleDateFormat">
				<constructor-arg value="yyyy-MM-dd" />
			</bean>
		</constructor-arg>
		<constructor-arg value="true" />
	</bean>

　　

 <bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
		<property name="customEditors">
			<map>
				<entry key="java.util.Date">
					<ref local="dateEditor" />
				</entry>
			</map>
		</property>
	</bean>

　　完整的配置為：

<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="dateEditor"
		class="org.springframework.beans.propertyeditors.CustomDateEditor">
 
		<constructor-arg>
			<bean class="java.text.SimpleDateFormat">
				<constructor-arg value="yyyy-MM-dd" />
			</bean>
		</constructor-arg>
		<constructor-arg value="true" />
 
	</bean>
 
	<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
		<property name="customEditors">
			<map>
				<entry key="java.util.Date">
					<ref local="dateEditor" />
				</entry>
			</map>
		</property>
	</bean>
 
	<bean id="customer" class="com.mkyong.common.Customer">
		<property name="date" value="2010-02-31" />
	</bean>
 
</beans>