Spring学习-- SpEL表达式

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;

 /**

  * @author Wáng Chéng Dá

  * @create 2017-03-02 13:48

  */

 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;

 /**

  * @author Wáng Chéng Dá

  * @create 2017-03-02 13:27

  */

 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;

/**

 * @author Wáng Chéng Dá

 * @create 2017-03-02 13:42

 */

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}'}

巴特西

Spring学习-- SpEL表达式

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