type Exception reportmessage An exception occurred processing JSP page /display.jsp at line 17description The server encountered an internal error that prevented it from fulfilling this request.exception org.apache.jasper.JasperException: An exception occurred processing JSP page /display.jsp at line 1714: <jsp:useBean id="dbBean" class="vote.DBConnect" scope="page" />
15: <%
16: String sql="select * from vote";
17: ResultSet rs=dbBean.executeQuery(sql);
18: %>
19: <table border=1 align="center" >
20: <tr >
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
15: <%
16: String sql="select * from vote";
17: ResultSet rs=dbBean.executeQuery(sql);
18: %>
19: <table border=1 align="center" >
20: <tr >
Stacktrace:
org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:568)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
完全可以去DBConnect类中调试看看
package vote;
import java.sql.*;public class DBConnect {
//设置连接数据库的参数
private String user = "root";
private String password = "199051";
//MySQL的JDBC驱动程序
String sDBDriver = "org.gjt.mm.mysql.Driver";
//连接数据库
String sConnStr = "jdbc:mysql://localhost:3306/vote?user&password";
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
public DBConnect() {
try {
//加载数据库驱动程序
Class.forName(sDBDriver);
//建立连接
conn = DriverManager.getConnection(sConnStr);
}
catch (Exception e) {
System.out.println("DBConnect():" + e.getMessage());
}
}
//查询
public ResultSet executeQuery(String sql) {
try {
stmt = conn.createStatement();
rs = stmt.executeQuery(sql);
}
catch (SQLException ex) {
System.out.println("sql.executeQuery:" + ex.getMessage());
}
return rs;
}
//更新
public boolean executeUpdate(String sql){
try{
stmt = conn.createStatement();
stmt.executeUpdate(sql);
return true;
}catch (SQLException ex) {
System.out.println("sql.executeUpdate:" + ex.getMessage());
return false;
}
}
//关闭数据库的连接
public void close() throws Exception{
conn.close();
stmt.close();
}
}
因为错误发生在17行ResultSet rs=dbBean.executeQuery(sql);
断点打在executeQuery方法内,调试单步执行,很快就能找出问题