Spring笔记 - Spring Expression Language (SpEL表达式)

基本表达式

数字5 <property name="count" value="#{5}"/>

联合方式 <property name="message" value="The value is #{5}"/>

浮点型 <property name="frequency" value="#{89.7}"/>

科学表达式10000.0 <property name="capacity" value="#{1e4}"/>

String <property name="name" value="#{'Chuck'}"/> <property name='name' value='#{"Chuck"}'/>

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

引用Bean <property name="instrument" value="#{saxophone}"/> 等价 <property name="instrument" ref="saxophone"/>

引用Bean属性 <property name="song" value="#{kenny.song}"/>

引用Bean方法 <property name="song" value="#{songSelector.selectSong()}"/>

进阶一 <property name="song" value="#{songSelector.selectSong().toUpperCase()}"/>

进阶二 防空指针 <property name="song" value="#{songSelector.selectSong()?.toUpperCase()}"/> 防空指针

使用静态类 T(java.lang.Math)

使用静态属性 <property name="multiplier" value="#{T(java.lang.Math).PI}"/>

使用静态方法 <property name="randomNumber" value="#{T(java.lang.Math).random()}"/>

运算表达式

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

- <property name="adjustedAmount" value="#{counter.total-20}"/>

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

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

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

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

+ overloaded <property name="fullName value="#{performer.firstName + ' ' + performer.lastName}"/>

== eq equal <property name="equal" value="#{counter.total==100}"/>

<= <propertyname="hasCapacity"value="#{counter.total le 100000}"/>

Equal== eq
Less than < lt
Less than or equals <= le
Greater than > gt
Greater than or equals >= ge

逻辑表达式

andA logical AND operation; both sides must evaluate true for the expression to be true
or A logical OR operation; either side must evaluate true for the expression to be true
not or ! A logical NOT operation; negates the target of the operation

<property name="largeCircle" value="#{shape.kind =='circle'andshape.perimeter gt 10000}"/>

<property name="outOfStock" value="#{!product.available}"/>

条件表达式 ?: <property name="instrument" value="#{songSelector.selectSong()=='JingleBells'?piano:saxophone}"/>

<propertyname="song" value="#{kenny.song !=null?kenny.song:'Greensleeves'}"/>

等价 Elvis operator <propertyname="song"value="#{kenny.song?:'Greensleeves'}"/>

正则表达式 <property name="validEmail"value= "#{admin.email matches '[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.com'}"/>

集合处理

<util:listid="cities">
<bean class="com.habuma.spel.cities.City"
p:name="Chicago"p:state="IL"p:population="2853114"/>
<bean class="com.habuma.spel.cities.City"
p:name="LasCruces"p:state="NM"p:population="91865"/>
</util:list>

List <property name="chosenCity" value="#{cities[2]}"/>

进阶 <property name="chosenCity" value="#{cities[T(java.lang.Math).random()*cities.size()]}"/>

Map <property name="chosenCity" value="#{cities['Dallas']}"/>

Properties <util:properties id="settings" location="classpath:settings.properties"/>

Properties <property name="accessToken" value="#{settings['twitter.accessToken']}"/>

systemEnvironment <property name="homePath" value="#{systemEnvironment['HOME']}"/>

systemProperties <property name="homePath" value="#{systemProperties['application.home']}"/>

String s 'This is a test'[3]

.?[] 条件选择成员 <property name="bigCities" value="#{cities.?[population gt 100000]}"/>

.^[] and .$[], for 第一个和最后一个匹配成员 <property name="aBigCity" value="#{cities.^[population gt 100000]}"/>

.![] 抽取集合 List <property name="cityNames" value="#{cities.![name]}"/>

进阶 <property name="cityNames" value="#{cities.![name+' , '+state]}"/>

进阶 <property name="cityNames" value="#{cities.?[population gt 100000].![name+' ,'+state]}"/>