Spring 在 xml配置文件或annotation注解中运用Spring EL

Spring EL

一：在Spring xml 配置文件中运用 Spring EL

Spring EL 采用 #{Sp Expression Language} 即 #{spring表达式}

1：运用EL表达式的配置文件如下：

<?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-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> 
<!-- more bean definitions for data access objects go here -->

<bean id="book" class="com.myapp.core.spel.xml.Book">
<property name="name" value="Effective Java" />
<property name="pages" value="300"/>
</bean>

<bean id="person" class="com.myapp.core.spel.xml.Person">
<property name="book" value="#{book}" />
<property name="bookName" value="#{book.name}"/>
</bean>
</beans>

在person bean 的配置中， 属性 book 引用了 book bean 通过EL表达式 形式是：<property name="book" value="#{book}" /> 相当于 在person bean中注入 book

person属性中的bookName属性注入了 book bean中的 name的值

2：测试以上配置：

Book类：

package com.myapp.core.spel.xml;

public class Book {
private  String  name ;
private  int   pages;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPages() {
return pages;
}
public void setPages(int pages) {
this.pages = pages;
}

}

Person类：

package com.myapp.core.spel.xml;

public class Person {
private  Book  book;

private  String  bookName;

public void setBook(Book book) {
this.book = book;
}

public Book getBook(){
return  this.book;
}

public  String   getBookName(){
return  this.bookName;
}

public void setBookName(String bookName) {
this.bookName = bookName;
}
}

测试类：

package com.myapp.core.spel.xml;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {
public static void main(String[] args) {

ApplicationContext  context  = new  ClassPathXmlApplicationContext("resource/spel.xml");

Person  person =  (Person)context.getBean("person");

System.out.println(person.getBookName());

System.out.println(person.getBook().getPages());
}
}

输出结果：

三月 18, 2013 5:17:18 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@11e831: startup date [Mon Mar 18 17:17:18 CST 2013]; root of context hierarchy
三月 18, 2013 5:17:18 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [resource/spel.xml]
三月 18, 2013 5:17:18 下午 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@498b39: defining beans [book,person]; root of factory hierarchy
Effective Java
300

二：注解中使用 EL

1：xml中配置，扫描含有注解的包；

<?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-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> 
<!-- more bean definitions for data access objects go here -->

<context:component-scan base-package="com.myapp.core.spel.annotation" />

</beans>

package com.myapp.core.spel.annotation;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("book")
public class Book {

@Value("Effective Java")
private  String  name ;

@Value("300")
private  int   pages;

public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getPages() {
return pages;
}
public void setPages(int pages) {
this.pages = pages;
}
}

package com.myapp.core.spel.annotation;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component("person")
public class Person {

@Value("#{book}")
private  Book  book;

@Value("#{book.name}")
private  String  bookName;

public void setBook(Book book) {
this.book = book;
}

public Book getBook(){
return  this.book;
}

public  String   getBookName(){
return  this.bookName;
}

public void setBookName(String bookName) {
this.bookName = bookName;
}
}

package com.myapp.core.spel.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {
public static void main(String[] args) {

ApplicationContext  context  = new  ClassPathXmlApplicationContext("resource/spel.xml");

Person  person =  (Person)context.getBean("person");

System.out.println(person.getBookName());

System.out.println(person.getBook().getPages());
}
}

三月 18, 2013 5:25:23 下午 org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@11e831: startup date [Mon Mar 18 17:25:23 CST 2013]; root of context hierarchy
三月 18, 2013 5:25:23 下午 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [resource/spel.xml]
三月 18, 2013 5:25:24 下午 org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider registerDefaultFilters
INFO: JSR-330 'javax.inject.Named' annotation found and supported for component scanning
三月 18, 2013 5:25:24 下午 org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor <init>
INFO: JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
三月 18, 2013 5:25:24 下午 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@543360: defining beans [book,person,org.springframework.context.annotation.internalConfigurationAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,org.springframework.context.annotation.internalCommonAnnotationProcessor]; root of factory hierarchy
Effective Java
300