在 Spring 中无法获取 JDBC 连接

Question

我是 Spring 新手，目前完全是 youtube tutorial。 当我通过 PostMan 的 GET 方法请求 api 时，出现以下奇怪的错误。

    SEVERE: Servlet.service() for servlet [dispatcher] in context with path [/SpringRESTFulExample] threw exception [Request processing failed; nested exception is org.springframework.jdbc.CannotGetJdbcConnectionException: Could not get JDBC Connection; nested exception is org.apache.tomcat.dbcp.dbcp.SQLNestedException: Cannot load JDBC driver class 'com.mysql.jdbc.Driver'] with root cause
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1720)
    at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1571)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createConnectionFactory(BasicDataSource.java:1420)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.createDataSource(BasicDataSource.java:1371)
    at org.apache.tomcat.dbcp.dbcp.BasicDataSource.getConnection(BasicDataSource.java:1044)
    at org.springframework.jdbc.datasource.DataSourceUtils.doGetConnection(DataSourceUtils.java:111)
    at org.springframework.jdbc.datasource.DataSourceUtils.getConnection(DataSourceUtils.java:77)
    at org.springframework.jdbc.core.JdbcTemplate.execute(JdbcTemplate.java:619)
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:684)
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:711)
    at org.springframework.jdbc.core.JdbcTemplate.query(JdbcTemplate.java:761)
    at org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate.query(NamedParameterJdbcTemplate.java:192)
    at springrestful_example.dao.UserDaoImpl.listAllUser(UserDaoImpl.java:30)
    at springrestful_example.service.UserServiceImpl.listAllUser(UserServiceImpl.java:22)
    at springrestful_example.controller.UserController.listAllUser(UserController.java:25)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:133)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:97)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:827)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:738)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:967)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:901)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:970)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:861)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:620)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:846)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:314)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)

本教程使用 JndiTemplate.lookup 进行连接。 就是这样。

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = "springrestful_example")
public class WebConfig {
    @Autowired
    DataSource dataSource;

    @Bean
    public NamedParameterJdbcTemplate getNamedParameterJdbcTemplate() {
        return new NamedParameterJdbcTemplate(dataSource);
    }

    @Bean
    public DataSource getDataSource() throws NamingException{
        JndiTemplate jndiTemplate = new JndiTemplate();
        DataSource dataSource = (DataSource) jndiTemplate.lookup("java:comp/env/jdbc/springrestful");
        return dataSource;
    }
}

在tomcat v7.0的server.xml中，除了数据库名之外，我按照教程进行如下配置。

<Context docBase="D:\zwh\WorkSpaces\JavaEE Workspace\SpringRESTFulExample\target\SpringRESTFulExample-0.0.1-SNAPSHOT\" path="/SpringRESTFulExample" reloadable="true">
    <Resource 
    auth="Container" 
    driverClassName="com.mysql.jdbc.Driver" 
    maxActive="5" maxIdle="3" 
    name="jdbc/springrestful" 
    passoword="" 
    type="javax.sql.DataSource" 
    url="jdbc:mysql://localhost:3306/springresttest" 
    username="root"/>

我错过了什么吗？我已经研究了这三天的时间，但我只发现了教程中没有涉及的不相关的东西。我试图更改 spring-jdbc 依赖项的版本。但也没有用。

Answer 1

将mysql-connector-java 依赖项添加到我的 pom.xml 后，我解决了我的问题。

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>6.0.6</version>
</dependency>

Answer 2

尝试添加这个依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
</dependency>