constract和 property的写法
<beans profile="test,local">-->
<!--<!– 本地，测试环境的 mail 服务配置 –>-->
<!--<bean name="sendMailService" />-->
<!--<constructor-arg index="1"-->
<!--type="org.springframework.mail.javamail.JavaMailSender" ref="mailSender" />-->
<!--<constructor-arg index="2" type="java.lang.String"-->
<!--value="${mail.from}" />-->
<!--</bean>-->
<!--</beans>-->


<!-- SCE 测试环境及正式环境下 mail 服务配置 -->
<bean name="sendMailService" type="org.apache.velocity.app.VelocityEngine"
ref="velocityEngine"/>
<property name="from" value="****@sohu-inc.com"/>
</bean>

@Autowired
private VelocityEngine velocityEngine;

private String from;

public SendMailService() {
}

public SendMailService(VelocityEngine velocityEngine) {
this.velocityEngine = velocityEngine;
}


public SendMailService(String from) {
this.from = from;
}