技術標籤：SSMspringmybatisssmspringmvc

使用SSM框架的時候我測試springmvc的時候遇到的錯誤：
一、Server Tomcat v9.0 Server at localhost failed to start.
啟動Tomcat服務的時候報錯資訊：
①Caused by: org.apache.catalina.LifecycleException: Failed to start component [StandardEngine[Catalina].StandardHost[localhost].StandardContext[/testSSM_2020_12_04_Evening_classes]] at org.apache.catalina.util.LifecycleBase.handleSubClassException(LifecycleBase.java:440)

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 
 xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd" id="WebApp_ID" version="4.0">
	
	<!-- needed for ContextLoaderListener -->
	<context-param>
		<param-name>
 
contextConfigLocation</param-name>
		<param-value>classpath:applicationContext.xml</param-value>
	</context-param>

	<!-- Bootstraps the root web application context before servlet initialization -->
	<listener>
		<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
	</listener>
	
	<!-- The front controller of this Spring Web application, responsible for handling all application requests -->
	<servlet>
		<servlet-name>springDispatcherServlet</servlet-name>
		<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
		<init-param>
			<param-name>contextConfigLocation</param-name>
			<param-value>/WEB-INF/springmvc.xml</param-value>
		</init-param>
		<load-on-startup>1</load-on-startup>
	</servlet>

	<!-- Map all requests to the DispatcherServlet for handling -->
	<servlet-mapping>
		<servlet-name>springDispatcherServlet</servlet-name>
		<url-pattern>url</url-pattern>
	</servlet-mapping>
	
	
</web-app>

解決辦法：把錯誤原因改寫為下面的

	<servlet-mapping>
		<servlet-name>springDispatcherServlet</servlet-name>
		<url-pattern>/</url-pattern>
	</servlet-mapping>
	

二、當我解決前一個問題，可以正常啟動之後又有這個錯誤了：HTTP Status 404 – 未找到
報錯資訊：[org.springframework.web.context.ContextLoaderListener] org.springframework.beans.factory.BeanDefinitionStoreException: Invalid bean definition with name 'dataSource' defined in class path resource [applicationContext.xml]: Could not resolve placeholder 'jdbc.driver' in value "${jdbc.driver}"; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'jdbc.driver' in value "${jdbc.driver}"
原因：我寫的資料庫連線的外部檔案db.properties的Driver是這樣的：
jdbc.jdbcDriver=com.mysql.jdbc.Driver
但是我spring配置檔案呼叫的時候是這樣寫的：

<property name="driverClass" value="${jdbc.driver}"></property>

這其中jdbc.Driver和jdbc.driver就不一樣就出錯了。
解決辦法：隨便改一個錯誤：就是要讓外部檔案的前面的值和裡面配置檔案取的值的名稱相同，才能找到

<property name="driverClass" value="${jdbc.jdbcDriver}"></property>

三、spring中mybatis報錯
錯誤報錯資訊：
①Caused by: org.springframework.core.NestedIOException: Failed to parse mapping resource: 'file [D:\eclipse\eclipse_new_new\web_new_new\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\testSSM_2020_12_04_Evening_classes\WEB-INF\classes\mybatis\mapper\UserMapper.xml]'; nested exception is org.apache.ibatis.builder.BuilderException: Error parsing Mapper XML. The XML location is 'file [D:\eclipse\eclipse_new_new\web_new_new\.metadata\.plugins\org.eclipse.wst.server.core\tmp1\wtpwebapps\testSSM_2020_12_04_Evening_classes\WEB-INF\classes\mybatis\mapper\UserMapper.xml]'. Cause: org.apache.ibatis.builder.BuilderException: Error resolving class. Cause: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Blog'. Cause: java.lang.ClassNotFoundException: Cannot find class: Blog
②
Caused by: org.apache.ibatis.type.TypeException: Could not resolve type alias 'Blog'. Cause: java.lang.ClassNotFoundException: Cannot find class: Blog
錯誤原因：
這個錯誤是因為我寫mapper.xml檔案（我的是UserMapper.xml）的時候是直接copymybatis3中文文件https://mybatis.org/mybatis-3/zh/getting-started.html中的樣例，然而我寫的專案中又不一樣

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.mybatis.example.BlogMapper">
  <select id="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select>
</mapper>

解決辦法：把那個無效的mapper.xml檔案UserMapper.xml檔案中的select方法註釋掉或者去掉

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.feng.SSMTest.dao.userMapper">
  <!-- <select id="selectBlog" resultType="Blog">
    select * from Blog where id = #{id}
  </select> -->
</mapper>

四、把以上三個問題解決了終於執行成功了

SSM框架每一部分都是有聯絡的，哪裡有一個問題都會影響全域性。每一個小問題都是大問題。