Spring-SpEL¶

SpelExpressionParser, EvaluationContext, parseExpression, @Value("#{ <expression string> }")

#{ <expression string> }, ${<property>}, T(<javaclass>)

SpEL see tutorial

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">

     <context:component-scan base-package="com.geeksforgeeks.spring" />

    <bean id="tutorial" class="com.geeksforgeeks.spring.Tutorial">
        <property name="topicsList">
           <ref local="javaCore" />
           <ref local="scalaBasics" />
        </property>
    </bean>

    <bean id="javaCore" class="com.geeksforgeeks.spring.Topic">
        <property name="name" value="JavaCore" />
    </bean>

    <bean id="scalaBasics" class="com.geeksforgeeks.spring.Topic">
        <property name="name" value="ScalaBasics" />
    </bean>   

    <bean id="training" class="com.geeksforgeeks.spring.Training">
        <property name="topic" value="#{tutorial.topicsList[1]}"/>
    </bean>

</beans>

SpEL see @Value("#{tutorial.topicsList[0]}")

public class Training
{
    private Topic topic;

    @Value("#{tutorial.topicsList[0]}")
    private Topic defaultTopic;

  //getters and setters
    public Topic getTopic()
    {
        return topic;
    }

    public void setTopic(Topic topic)
    {
        this.topic = topic;
    }

    public Topic getDefaultTopic()
    {
        return defaultTopic;
    }
}

Spring表达式编程入门

answer :

圖 :

ParserContext表达式分隔符¶

default 分割符號 ===#{ xxx }===

一般情況使用 #{ xxx }¶

SpEL字面表达式¶

SpEL字面表达式¶

SpEL数学表达式¶

SpEL关系表达式¶

SpEL逻辑表达式¶

SpEL三目运算符¶

SpEL解析原理¶

parseExpression¶

getValue¶

SpEL与反射处理¶

public static void main(String[] args)throws Exception{//该抛就抛
    L0G6ER.info("【#{T(java.lang.String).}\"】Class表达式：{}"，
    spel(content:"#T(java.lang.String)}").getclass())
}
public static Object spel(String content){//实现了SpEL处理
    ExpressionParser parser=new SpelExpressionParser();//定义SpEL解析器
    Expression exp=parser.parseExpression(content,ParserContext.TEMPLATE_EXPRESSION);//表达式解析
    EvaluationContext context=new StandardEvaluationContext();//表达式上下文配置
    return exp.getValue(context);
}

呼叫靜態方法¶

new Bean¶

方法¶

SpEL变量操作¶

傳入參數¶

ans:¶

根變量¶

方法引用¶

實現類屬性方法調用¶

SpEL定义List集合表达式¶

SpEL定义Map集合¶

修改 map 內容

map to list

Spring配置文件使用SpEL处理字符串¶

Annotation整合SpEL¶

Profile与SpEL¶

PropertySource属性源¶

mapProperties

PropertyResolver属性解析¶

解析

PropertySourcesPlaceholderConfigurer属性资源配置¶