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转载自 https://www.cnblogs.com/goodcheap/p/6490896.html
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。
1 <?xml version="1.0" encoding="UTF-8"?> 2 <beans xmlns="http://www.springframework.org/schema/beans" 3 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4 xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> 5 6 <bean id="car" class="com.itdjx.spring.spel.Car"> 7 <property name="brand" value="#{'玛莎拉蒂'}"></property> 8 <property name="price" value="#{32000.78}"></property> 9 <property name="perimeter" value="#{T(java.lang.Math).PI * 75.8f}"></property> 10 </bean> 11 12 <bean id="person" class="com.itdjx.spring.spel.Person"> 13 <property name='name' value='#{"华崽儿"}'></property> 14 <property name="age" value="#{25}"></property> 15 <property name="marriage" value="#{car.price > 400000 and age > 30}"></property> 16 <property name="car" value="#{car}"></property> 17 <property name="socialStatus" value="#{car.price > 30000 ? '金领' : '白领'}"></property> 18 <property name="address" value="#{address.province + '省' + address.city + '市' + address.area + '区'}"/> 19 </bean> 20 21 <bean id="address" class="com.itdjx.spring.spel.Address"> 22 <property name="province" value="#{'辽宁'}"/> 23 <property name="city" value="#{'大连'}"/> 24 <property name="area" value="#{'沙河口'}"/> 25 </bean> 26 27 </beans>
1 package com.itdjx.spring.spel; 2 3 /** 4 * @author Wáng Chéng Dá 5 * @create 2017-03-02 13:26 6 */ 7 public class Car { 8 9 private String brand; 10 11 private double price; 12 13 private String perimeter; 14 15 public String getBrand() { 16 return brand; 17 } 18 19 public void setBrand(String brand) { 20 this.brand = brand; 21 } 22 23 public double getPrice() { 24 return price; 25 } 26 27 public void setPrice(double price) { 28 this.price = price; 29 } 30 31 public String getPerimeter() { 32 return perimeter; 33 } 34 35 public void setPerimeter(String perimeter) { 36 this.perimeter = perimeter; 37 } 38 39 @Override 40 public String toString() { 41 return "Car{" + 42 "brand='" + brand + '\'' + 43 ", price=" + price + 44 ", perimeter='" + perimeter + '\'' + 45 '}'; 46 } 47 }
1 package com.itdjx.spring.spel; 2 3 /** 4 * @author Wáng Chéng Dá 5 * @create 2017-03-02 13:48 6 */ 7 public class Address { 8 9 private String province; 10 11 private String city; 12 13 private String area; 14 15 public String getProvince() { 16 return province; 17 } 18 19 public void setProvince(String province) { 20 this.province = province; 21 } 22 23 public String getCity() { 24 return city; 25 } 26 27 public void setCity(String city) { 28 this.city = city; 29 } 30 31 public String getArea() { 32 return area; 33 } 34 35 public void setArea(String area) { 36 this.area = area; 37 } 38 39 @Override 40 public String toString() { 41 return "Address{" + 42 "province='" + province + '\'' + 43 ", city='" + city + '\'' + 44 ", area='" + area + '\'' + 45 '}'; 46 } 47 }
1 package com.itdjx.spring.spel; 2 3 /** 4 * @author Wáng Chéng Dá 5 * @create 2017-03-02 13:27 6 */ 7 public class Person { 8 9 private String name; 10 11 private int age; 12 13 private boolean marriage; 14 15 private Car car; 16 17 private String socialStatus; 18 19 private String address; 20 21 public String getName() { 22 return name; 23 } 24 25 public void setName(String name) { 26 this.name = name; 27 } 28 29 public int getAge() { 30 return age; 31 } 32 33 public void setAge(int age) { 34 this.age = age; 35 } 36 37 public boolean isMarriage() { 38 return marriage; 39 } 40 41 public void setMarriage(boolean marriage) { 42 this.marriage = marriage; 43 } 44 45 public Car getCar() { 46 return car; 47 } 48 49 public void setCar(Car car) { 50 this.car = car; 51 } 52 53 public String getSocialStatus() { 54 return socialStatus; 55 } 56 57 public void setSocialStatus(String socialStatus) { 58 this.socialStatus = socialStatus; 59 } 60 61 public String getAddress() { 62 return address; 63 } 64 65 public void setAddress(String address) { 66 this.address = address; 67 } 68 69 @Override 70 public String toString() { 71 return "Person{" + 72 "name='" + name + '\'' + 73 ", age=" + age + 74 ", marriage=" + marriage + 75 ", car=" + car + 76 ", socialStatus='" + socialStatus + '\'' + 77 ", address='" + address + '\'' + 78 '}'; 79 } 80 }
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}’}
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