SpringMVC实现发送邮件

<!--spring发送邮件依赖spring.version=4.3.8.RELEASE-->
<dependency>
 <groupId>org.springframework</groupId>
 <artifactId>spring-context-support</artifactId>
 <version>${spring.version}</version>
</dependency>

<!-- Javamail API -->
<dependency>
 <groupId>javax.mail</groupId>
 <artifactId>mail</artifactId>
 <version>1.4.5</version>
</dependency>

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       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-4.2.xsd
    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.2.xsd">

<!-- 引入属性文件 -->
    <context:property-placeholder location="classpath:config/email.properties" ignore-unresolvable="true"/>

   <!-- <bean id="local" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:config/email.properties" />
        <property name="ignoreUnresolvablePlaceholders" value="true" />
    </bean>-->
    <!--
        下面列出网易的SMTP服务器名和端口号:
         网易邮箱          SMTP服务器     SMTP端口     POP3服务器       POP3端口
         @126.com        smtp.126.com      25          pop3.126.com      110
         @163.com        smtp.163.com      25          pop3.163.com      110
         @yeah.net       smtp.yeah.net      25          pop3.yeah.net     110
     -->
    <bean id="javaMailSender"
          class="org.springframework.mail.javamail.JavaMailSenderImpl">
        <property name="protocol" value="${email.protocol}"/>
        <property name="host" value="${email.host}"/>
        <property name="port" value="${email.port}"/>
        <property name="username" value="${email.username}"/>
        <property name="password" value="${email.password}"/>
        <property name="defaultEncoding" value="UTF-8"></property>
        <property name="javaMailProperties">
            <props>
                <prop key="mail.auth">${email.auth}</prop>
                <prop key="mail.smtp.timeout">${email.timout}</prop>
            </props>
        </property>

    </bean>

    <bean id="simpleMailMessage" class="org.springframework.mail.SimpleMailMessage">
        <!-- 发件人email -->
        <property name="from" value="${email.username}" />
         <!--收件人email-->
        <property name="to" value="${email.default.to}" />
        <!--email主题(标题)-->
        <property name="subject" value="${email.default.subject}" />
        <!--email主题内容-->
        <property name="text">
          <value>${email.default.text}</value>
        </property>
    </bean>

    <bean id="emailService"
          class="com.website.service.impl.EmailServiceImpl">
        <property name="javaMailSender" ref="javaMailSender"/>
        <property name="simpleMailMessage" ref="simpleMailMessage"/>
    </bean>
</beans>

email.protocol=smtp
email.host=smtp.163.com
email.port=25
email.username=132312312@163.com
email.password=yourpassword
email.default.to=123121@126.com
email.default.subject=Hello
email.default.text=how are you
email.auth=true
email.timout=25000

public class EmailServiceImpl implements EmailService {

    private static final Logger LOGGER = LoggerFactory.getLogger(EmailServiceImpl.class);

    private JavaMailSender javaMailSender;

    private SimpleMailMessage simpleMailMessage;

    /**
     * @方法名: sendMailSimple
     * @参数名：@param subject  邮件主题
     * @参数名：@param content 邮件内容
     * @参数名：@param to     收件人Email地址
     * @描述语: 发送邮件
     */
    @Override
    public void sendMailSimple(String to, String subject, String content) throws Exception {

        try {
            //用于接收邮件的邮箱
            simpleMailMessage.setTo(to);
            //邮件的主题
            simpleMailMessage.setSubject(subject);
            //邮件的正文，第二个boolean类型的参数代表html格式
            simpleMailMessage.setText(content);

            LOGGER.info("---------------------------{}", simpleMailMessage);
            //发送
            javaMailSender.send(simpleMailMessage);

        } catch (Exception e) {
            throw new MessagingException("failed to send mail!", e);
        }
    }

    public void setJavaMailSender(JavaMailSender javaMailSender) {
        this.javaMailSender = javaMailSender;
    }

    public void setSimpleMailMessage(SimpleMailMessage simpleMailMessage) {
        this.simpleMailMessage = simpleMailMessage;
    }
}

Caused by: org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'javaMailSender' defined in class path resource [config/spring-mail.xml]: Could not resolve placeholder 'email.protocol' in value "${email.protocol}"; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'email.protocol' in value "${email.protocol}"

<context:property-placeholder location="classpath:config/db.properties"/>

<context:property-placeholder location="classpath:config/email.properties"/>

<context:property-placeholder location="classpath:config/db.properties" ignore-unresolvable="true"/>

<context:property-placeholder location="classpath:config/email.properties" ignore-unresolvable="true"/>

<bean id="local" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="classpath:config/email.properties" />
        <property name="ignoreUnresolvablePlaceholders" value="true" />
    </bean>