我连接mysql数据库时报这个异常!
Class.forName(DBconst.CLASSNAME).newInstance(); 无法指向运行DBconst类!
java.lang.ClassNotFoundException:
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Unknown Source)
at com.dbconn.Connect.<init>(Connect.java:21)
at com.user.Addbook.<init>(Addbook.java:10)
at com.servlet.Add.doGet(Add.java:36)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:627)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:875)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Unknown Source)
package com.dbconn;
import java.util.*;
import java.io.*;
public class DBconst {
public static String CLASSNAME="";
public static String url="";
public static String username="";
public static String password="";
public DBconst(){
Properties prop=new Properties();
System.out.println("获得数据");
InputStream in=this.getClass().getResourceAsStream("DB.properties");//获得配置文件
try{
prop.load(in);
}catch(Exception e){
System.out.println("数据加载异常:"+e.getMessage());
}
/**
* 获得相关数据库的连接信息
*/
CLASSNAME=prop.getProperty("ClassName");
System.out.println();
url=prop.getProperty("url");
username=prop.getProperty("username");
password=prop.getProperty("password");
}
}