Spring 在 xml配置文件 或 annotation 注解中 運用Spring EL表達式

Spring  EL

一：在Spring xml 配置文件中運用   Spring EL

Spring EL 采用 #{Sp Expression  Language} 即 #{spring表達式}

1：運用EL表達式的配置文件如下：

<?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， 屬性 book 引用了  book bean 通過EL表達式 形式是：<property name="book" value="#{book}" /> 相當於 在person bean中注入 book

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

2：測試以上配置：

Book類：

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類：

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;
}
}

 

測試類：

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());
    }
}

輸出結果：

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，掃描含有注解的包；

<?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>

2：相應的類：

Book類：

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;
    }
}

在book的屬性中 注入了值。

Person類：

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;
    }
}

在Person類中 

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

注入book到person 通過EL表達式的方式

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

同樣以上的bookName也是通過EL表達式的方式

 

測試類：

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());
        }
    }

測試結果：

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