采用变量方式统一管理maven的jar包版本

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0modelVersion>
  <groupId>com.kevingroupId>
  <artifactId>kevin_proartifactId>
  <version>0.0.1-SNAPSHOTversion>
  <packaging>warpackaging>
  <name>kevin_proname>

  <properties>
    
    <com.sun.faces.version>2.2.6com.sun.faces.version>
  properties>
  <dependencies>
    
    <dependency>
    <groupId>com.sun.facesgroupId>
    <artifactId>jsf-apiartifactId>
    <version>${com.sun.faces.version}version>
    dependency>

    
    <dependency>
    <groupId>com.sun.facesgroupId>
    <artifactId>jsf-implartifactId>
    <version>${com.sun.faces.version}version>
    dependency>
  dependencies>
  <build>
    <finalName>kevin_profinalName>
  build>
project>

需要注意的是，${com.sun.faces.version}中不能有空格，例如，${com.sun.faces.version }（version后面有一个空格）就不行。