Spring 表达式语言(简称SpEL)：是一个支持运行时查询和操作对象图的强大的表达式语言。
语法类似于 EL：SpEL 使用 #{...} 作为定界符 , 所有在大括号中的字符都将被认为是 SpEL , SpEL 为 bean 的属性进行动态赋值提供了便利。
通过 SpEL 可以实现：
通过 bean 的 id 对 bean 进行引用。
调用方式以及引用对象中的属性。
计算表达式的值
正则表达式的匹配。
<?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">
<bean id="car" class="com.itdjx.spring.spel.Car">
<property name="brand" value="#{'玛莎拉蒂'}"></property>
<property name="price" value="#{32000.78}"></property>
<property name="perimeter" value="#{T(java.lang.Math).PI * 75.8f}"></property>
</bean>
<bean id="person" class="com.itdjx.spring.spel.Person">
<property name='name' value='#{"华崽儿"}'></property>
<property name="age" value="#{25}"></property>
<property name="marriage" value="#{car.price > 400000 and age > 30}"></property>
<property name="car" value="#{car}"></property>
<property name="socialStatus" value="#{car.price > 30000 ? '金领' : '白领'}"></property>
<property name="address" value="#{address.province + '省' + address.city + '市' + address.area + '区'}"/>
</bean>
<bean id="address" class="com.itdjx.spring.spel.Address">
<property name="province" value="#{'辽宁'}"/>
<property name="city" value="#{'大连'}"/>
<property name="area" value="#{'沙河口'}"/>
</bean>
</beans>
package com.itdjx.spring.spel;
/**
* @author Wáng Chéng Dá
* @create 2017-03-02 13:26
*/
public class Car {
private String brand;
private double price;
private String perimeter;
public String getBrand() {
return brand;
}
public void setBrand(String brand) {
this.brand = brand;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public String getPerimeter() {
return perimeter;
}
public void setPerimeter(String perimeter) {
this.perimeter = perimeter;
}
@Override
public String toString() {
return "Car{" +
"brand='" + brand + '\'' +
", price=" + price +
", perimeter='" + perimeter + '\'' +
'}';
}
}
package com.itdjx.spring.spel;
public class Address {
private String province;
private String city;
private String area;
public String getProvince() {
return province;
}
public void setProvince(String province) {
this.province = province;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getArea() {
return area;
}
public void setArea(String area) {
this.area = area;
}
@Override
public String toString() {
return "Address{" +
"province='" + province + '\'' +
", city='" + city + '\'' +
", area='" + area + '\'' +
'}';
}
}
package com.itdjx.spring.spel;
public class Person {
private String name;
private int age;
private boolean marriage;
private Car car;
private String socialStatus;
private String address;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public boolean isMarriage() {
return marriage;
}
public void setMarriage(boolean marriage) {
this.marriage = marriage;
}
public Car getCar() {
return car;
}
public void setCar(Car car) {
this.car = car;
}
public String getSocialStatus() {
return socialStatus;
}
public void setSocialStatus(String socialStatus) {
this.socialStatus = socialStatus;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "Person{" +
"name='" + name + '\'' +
", age=" + age +
", marriage=" + marriage +
", car=" + car +
", socialStatus='" + socialStatus + '\'' +
", address='" + address + '\'' +
'}';
}
}
package com.itdjx.spring.spel;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class Main {
public static void main(String[] args) {
ApplicationContext app = new ClassPathXmlApplicationContext("spel-beans.xml");
Person person = (Person) app.getBean("person");
System.out.println(person);
}
}
控制台输出：
Person{name='华崽儿', age=25, marriage=false, car=Car{brand='玛莎拉蒂', price=32000.78, perimeter='238.13273272948624'}, socialStatus='金领', address='辽宁省大连市沙河口区'}
SpEL 字面量：
整数：#{8}
小数：#{8.8}
科学计数法：#{1e4}
String：可以使用单引号或者双引号作为字符串的定界符号。
Boolean：#{true}
SpEL引用bean , 属性和方法：
引用其他对象:#{car}
引用其他对象的属性：#{car.brand}
调用其它方法 , 还可以链式操作：#{car.toString()}
调用静态方法静态属性：#{T(java.lang.Math).PI}
SpEL支持的运算符号：
算术运算符：+，-，*，/，%，^(加号还可以用作字符串连接)
比较运算符：< , > , == , >= , <= , lt , gt , eg , le , ge
逻辑运算符：and , or , not , |
if-else 运算符(类似三目运算符)：？:(temary), ?:(Elvis)
正则表达式：#{admin.email matches '[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}'}
