1.異常描述
org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'xxx' defined in URL[file:/xxxx/xxx.xml]: Could not resolve place holder 'xxx' in string value 'xxx': nexted exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'xxxx' in string value 'xxx'
原因：
<context:property-placeholder location="classpath:jdbc.properties"/>
<context:property-placeholder location="classpath:redis.properties"/>
原因分析：是否存在多個context:property-placeholder，在spring中只會使第一個生效，其後的被忽略，如果需要配置多個properties，在location中使用逗號隔開即可。如location="classpath:xxx1.properties,classpath:xxx2.properties"
應該爲：<context:property-placeholder location="classpath:jdbc.properties,classpath:redis.properties"/>
2.
tomcat控制檯亂碼，解決：
在tomcat根目錄下的conf目錄下找到logging.properties，打開後將UTF-8全部替換成GBK即可
3.org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'sqlSessionFactory' defined in file [D:\搜狗高速下載\apache-tomcat-9.0.22-windows-x64\apache-tomcat-9.0.22\webapps\ssm_war\WEB-INF\classes\spring\spring-dao.xml]: Invocation of init method failed; nested exception is org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [D:\搜狗高速下載\apache-tomcat-9.0.22-windows-x64\apache-tomcat-9.0.22\webapps\ssm_war\WEB-INF\classes\mapper\OrderDao.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. Cause: java.lang.NullPointerException
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1566)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
錯誤原因：mapper文件忘了填namespace