pom.xml中properties作用

可以在properties下声明相应的版本信息，然后在dependency下引用的时候用${spring-version}就可以引入该版本jar包了

<properties>

        <spring-version>4.3.7.RELEASE</spring-version>

    </properties>

    <!--dependencies-->

    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-web</artifactId>
            <version>${spring-version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${spring-version}</version>
        </dependency>

    </dependencies>