Spring错误：java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory

第一次搭建Spring框架，编写并运行例子时出现如下错误：

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory
	at org.springframework.context.support.AbstractApplicationContext.(AbstractApplicationContext.java:164)
	at org.springframework.context.support.AbstractApplicationContext.(AbstractApplicationContext.java:228)
	at org.springframework.context.support.AbstractRefreshableApplicationContext.(AbstractRefreshableApplicationContext.java:89)
	at org.springframework.context.support.AbstractRefreshableConfigApplicationContext.(AbstractRefreshableConfigApplicationContext.java:58)
	at org.springframework.context.support.AbstractXmlApplicationContext.(AbstractXmlApplicationContext.java:61)
	at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:136)
	at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83)
	at com.chapter1.TestSpring.main(TestSpring.java:11)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory
	at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
	at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
	... 8 more

解决方法：缺少commons-logging.jar，下载jar包（如commons-logging-1.2.jar），添加到项目中。