Spring 通过 SpEL 为 bean 赋值

SpEL 字面量的表示

1. 整数：<property name = "count" value="#{5}"/>

2. 小数：<property name = "frequency" value="#{89.7}"/>

3. 科学计数法：<property name = "capacity" value="#{1e4}"/>

4. 字符串：<property name = "name" value="#{'Chuck'}"/>或<property name = 'name' value='#{"Chuck"}'/>

5. Boolean： <property name = "enabled" value="#{false}"/>

 <bean id="address" class="com.sangyu.test02.Address">
        <property name="city" value="#{'Beijing'}"></property>
        <property name="street" value="Wudaokou"></property>
</bean>

SpEL 引用 Bean、属性和方法

1. 引用其他对象：

<property name = "prefix" value="#{prefixGenerator}"/>

2. 引用其他对象的属性

<property name = "suffix" value="#{sequenceGenerator2.suffix}"/>

3. 调用其他方法

<property name = "suffix" value="#{sequenceGenerator2.suffix}"/>

4. 链式操作

<property name = "suffix" value="#{sequenceGenerator2.toString().toUpperCase()}"/>

// 引用类的静态属性
<bean id="address" class="com.sangyu.test02.Address">
    <property name="city" value="#{'Beijing'}"></property>
    <property name="street" value="Wudaokou"></property>
</bean>

<bean id="car" class="com.sangyu.test02.Car">
    <property name="brand" value="Audi"></property>
    <property name="price" value="#{T(java.lang.Math).PI * 80}"></property>
</bean>

SpEL 支持的运算符号

1. 算数运算符：+ - * / % ^

<property name = "adjustAmout" value="#{counter.total + 42}"/>

<property name = "adjustAmout" value="#{counter.total - 42}"/>

<property name = "adjustAmout" value="#{2 * T(java.lang.Math).PI * circle.radius}"/>

<property name = "adjustAmout" value="#{counter.total / counter.count}"/>

<property name = "adjustAmout" value="#{counter.total % counter.count}"/>

<property name = "adjustAmout" value="#{T(java.lang.Math).PI * circle.radius ^ 2}"/>

2. 加号还可以用作字符串连接

<constructor-arg value = "#{performer.fistName + ' ' + performer.lastName}"/>

3. 比较运算符：< > == <= >= lt gt eg le ge
   <property name = "equal" value="#{counter.total == 100}"/>
<property name = "hasCapacity" value="#{counter.total le 1000000}"/>

<bean id="address" class="com.sangyu.test02.Address">
    <property name="city" value="#{'Beijing'}"></property>
    <property name="street" value="Wudaokou"></property>
</bean>

<bean id="car" class="com.sangyu.test02.Car">
    <property name="brand" value="Audi"></property>
    <property name="price" value="#{T(java.lang.Math).PI * 80}"></property>
</bean>

<bean id="person" class="com.sangyu.test02.Person">
    <property name="car" value="#{car}"></property>  <!-- 引用其他bean-->
    <property name="city" value="address.city"></property> <!-- 引用其他bean的属性-->
    <property name="info" value="#{car.price > 30000 ? '金领' : '白领'}"></property> <!-- 使用运算符-->
    <property name="name" value="Tom"></property>
</bean>