mysql连接在本地运行良好，但在rest函数调用[java]中调用时失败

Question

我正在用REST+Mysql+Java做一个小项目。休息电话工作正常。但当我在rest函数中进行任何数据库事务时，比如我想在rest调用中从数据库中获取一些值，那么它就会给出[java.lang.ClassNotFoundException: com.mysql.jdbc.Driver]。当我通过类的obj调用同一个函数时，它工作正常，但如果通过restapi调用调用，它会失败。当我对函数进行rest调用时，数据也是通过参数和自变量来的，我可以在函数体中使用它，但不能执行数据库事务。

我在ASP.net 上发现了一个相同的问题

我已经将mysql-jar添加到类路径以及WEB-INF/lib/folder 中

我的连接类别：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class conectionclass {
public static Connection getConnection(){
Connection conn = null ;
try {
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection( "jdbc:mysql://localhost:3306/emps","root", "12345" );
System.out.println("-------------  Connection Succesful ----------------"); 
} catch (SQLException | ClassNotFoundException e) {
// TODO Auto-generated catch block
System.out.println("-------------  Connection Fail ----------------"); 
e.printStackTrace();
}
return conn;
}
}

我的休息功能：

@POST
@Path("/postjson")
@Produces("application/json")
public Employee  getJSONfromApp(HashMap p) {
return ( new empdao()).getEmployee("test", "1234") ; 
}

员工刀类功能：

@Override
public  Employee getEmployee(String employee, String pass) {
int count = 0 ;
Connection conn = Connectionclass.getConnection();
//       System.out.println("Employee : "+employee+"  Connection : "+conn);
if(employee!=null || employee != "" )
{
String query =   "select * from emps where username = '"+employee+"' && pass = '"+pass+"'  ";
try {
Statement stmt  = conn.createStatement() ;
System.out.println("Statement created.."+ stmt);
ResultSet a =  stmt.executeQuery(query);
while(a.next()){
return (new Employee(a.getString(2) , a.getString(3) ));
} 
} catch (Exception e) {
// TODO Auto-generated catch block
System.out.println("Error in  connection.....");
//                  e.printStackTrace();
} finally{
try {
conn.close();
} catch ( Exception e) {
System.out.println("Error in closing connection.....");
//                      e.printStackTrace();
}
}
}
return null;
}

通过RestService调用时的输出：

-------------  Connection Fail ----------------
java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1305)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1157)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:259)
at com.app.App3.Connectionclass.getConnection(Connectionclass.java:13)
at com.app.App3.empdao.getEmployee(empdao.java:47)
at com.mkyong.rest.JSONService.getJSONfromApp(JSONService.java:90)
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:483)
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:140)
at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:255)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:220)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:209)
at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:519)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:496)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:119)
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:291)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:239)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:142)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:610)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:518)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1091)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:668)
at org.apache.coyote.http11.Http11NioProtocol$Http11ConnectionHandler.process(Http11NioProtocol.java:223)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1517)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1474)
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:744)
Error in  connection.....

Answer 1

得到了答案，实际上我的tomcat版本和jre版本不同。当我让他们解决了同样的上述问题。