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Spring学习-- SpEL表达式
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轉載自?https://www.cnblogs.com/goodcheap/p/6490896.html
目錄
Spring 表達式語言(簡稱SpEL)：是一個支持運行時查詢和操作對象圖的強大的表達式語言。
語法類似于 EL：SpEL 使用 #{...} 作為定界符 , 所有在大括號中的字符都將被認為是 SpEL , SpEL 為 bean 的屬性進行動態賦值提供了便利。
通過 SpEL 可以實現：
- 通過 bean 的 id 對 bean 進行引用。
- 調用方式以及引用對象中的屬性。
- 計算表達式的值
- 正則表達式的匹配。
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="#{'瑪莎拉蒂'}"></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='#{"華崽兒"}'></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 ? '金領' : '白領'}"></property>
18 <property name="address" value="#{address.province + '省' + address.city + '市' + address.area + '區'}"/>
19 </bean>
20
21 <bean id="address" class="com.itdjx.spring.spel.Address">
22 <property name="province" value="#{'遼寧'}"/>
23 <property name="city" value="#{'大連'}"/>
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);}
}
?
控制臺輸出：
| Person{name='華崽兒', age=25, marriage=false, car=Car{brand='瑪莎拉蒂', price=32000.78, perimeter='238.13273272948624'}, socialStatus='金領', address='遼寧省大連市沙河口區'} |
?
?SpEL 字面量：
- 整數：#{8}
- 小數：#{8.8}
- 科學計數法：#{1e4}
- String：可以使用單引號或者雙引號作為字符串的定界符號。
- Boolean：#{true}
SpEL引用bean , 屬性和方法：
- 引用其他對象:#{car}
- 引用其他對象的屬性：#{car.brand}
- 調用其它方法 , 還可以鏈式操作：#{car.toString()}
- 調用靜態方法靜態屬性：#{T(java.lang.Math).PI}
?SpEL支持的運算符號：
- 算術運算符：+，-，*，/，%，^(加號還可以用作字符串連接)
- 比較運算符：< , > , == , >= , <= , lt , gt , eg , le , ge
- 邏輯運算符：and , or , not , |
- if-else 運算符(類似三目運算符)：？:(temary), ?:(Elvis)
- 正則表達式：#{admin.email matches '[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,4}'}
總結
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