SpringEL表达式（一）-入门案例

原文链接：http://www.yiidian.com/spring/spring-el-helloworld.html

在Spring3中就已经支持EL表达式了, Spring Expression Language(SpEL)是类似于OGNL和JSF EL的表达式语言, 能够在运行时构建复杂表达式, 存取对象属性、调用对象方法等, 而且所有的SpEL都支持XML和Annotation两种方式, 使用的格式均为:#{SpEL expression}。

下面的例子，这个例子将展示如何利用SpEL注入String、Bean到属性中。

一、编写Bean类

Customer.java

package com.yiidian.domain;

import java.io.Serializable;
/**
 * 
 * @author http://www.yiidian.com
 *
 */
public class Customer implements Serializable{
    private String name;
    private String telephone;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getTelephone() {
        return telephone;
    }
    public void setTelephone(String telephone) {
        this.telephone = telephone;
    }
}

CustomerDao接口：

/**
 * 
 * @author http://www.yiidian.com
 *
 */
public interface CustomerDao {
}

CustomerDaoImpl类：

注意：在这个类中注入Customer对象和custName的字符串。

package com.yiidian.dao.impl;

import com.yiidian.dao.CustomerDao;
import com.yiidian.domain.Customer;
/**
 * @author http://www.yiidian.com
 *
 */
public class CustomerDaoImpl implements CustomerDao {
    
    private Customer customer;
    private String custName;
    public void setCustomer(Customer customer) {
        this.customer = customer;
    }
    public void setCustName(String custName) {
        this.custName = custName;
    }

    @Override
    public String toString() {
        return "CustomerDaoImpl [customer=" + customer + ", custName=" + custName + "]";
    }
    
}

二、编写applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:p="http://www.springframework.org/schema/p"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="customer" class="com.yiidian.domain.Customer">
        <property name="name" value="张三"/>
        <property name="telephone" value="13666666666"/>
    </bean>

     <bean id="customerDao" class="com.yiidian.dao.impl.CustomerDaoImpl">
        <!--
             #{customer}:注入Customer对象
             #{customer.name}： 注入Cutomer的name属性值
         -->
         <property name="customer" value="#{customer}"></property>
         <property name="custName" value="#{customer.name}"></property>
     </bean>
    
</beans>

三、编写测试

package com.yiidian.test;

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

import com.yiidian.dao.CustomerDao;

/**
 * @author http://www.yiidian.com
 * 
 */
public class Demo1 {

    @Test
    public void test1() {
        ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
        CustomerDao customerDao = (CustomerDao)context.getBean("customerDao");
        System.out.println(customerDao);
    }

}

四、运行结果

file

源码下载：http://pan.baidu.com/s/1i4HlQzb