springmvc xml文件配置中使用系统环境变量

来源:how to read System environment variable in Spring applicationContext

答案：

In order to access system environment variable, that is OS level variables as amoe commented, we can simply use "systemEnvironment" instead of "systemProperties" in that EL. Like #{systemEnvironment['ENV_VARIABLE_NAME']}

使用SpringEL表达式来获取

#{systemEnvironment['ENV_VARIABLE_NAME']}

例如:

 <!--上传文件-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <property name="defaultEncoding" value="UTF-8"/>
        <property name="uploadTempDir" value="file://#{systemEnvironment['TEMP']}"/>
    </bean>

可能需要以下依赖

  <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-core</artifactId>
      <version>4.2.5.RELEASE</version>
    </dependency>   
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>4.2.5.RELEASE</version>
    </dependency>