White spaces are required between publicId and systemId.

在配置applicationContext.xml时，编译器报错。

是因为XML的标签顺序导致。

<?xml version="1.0" encoding="UTF-8"?>
<beans
  xmlns="http://www.springframework.org/schema/beans"
 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

 xmlns:context="http://www.springframework.org/schema/context"

 xmlns:tx="http://www.springframework.org/schema/tx"
 
 xmlns:aop="http://www.springframework.org/schema/aop"
 
 xsi:schemaLocation="

  http://www.springframework.org/schema/beans

  http://www.springframework.org/schema/beans/spring-beans-2.5.xsd

  http://www.springframework.org/schema/context

        http://www.springframework.org/schema/context/spring-context-2.5.xsd

        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop.xsd
        http://www.springframework.org/schema/tx
                     
        http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

        </beans>

这是完整的标签。