Question

这是代码。

        String Driver="com.mysql.jdbc.Driver";
        String Url="jdbc:mysql://localhost:3306/studentdata";
        String username="root";
        String password="";

        Class.forName(Driver);
        Connection con=null;
        Statement stment=null;

        try{
            con=DriverManager.getConnection(Url,username,password);
           String Sqlquery="INSERT INTO `students`(`Name`, `FatherName`, `ClassNo`,
                 `Phone`, `Address`)"+

                "VALUES(" + "'" +request.getParameter("studentName")+ "'" + "," + "'"

                 + request.getParameter("FatherName")+ "'" + ","

                 + "'" + request.getParameter("ClassNo")+ "'" + "," 

                 + "Address= "+ "'" + request.getParameter("studentAddress")+ "'" + ","

                 + "Phone= "+ "'" + request.getParameter("studentPhone")+ "'" + ");";

            stment=con.createStatement();
            stment.executeUpdate(Sqlquery);

            stment.close();
            con.close();
        }catch(SQLException e){
            e.printStackTrace();
        }


        String Selectquery="SELECT * FROM students";
        ResultSet result=null;
        try{
            stment=con.createStatement();
            result=stment.executeQuery(Selectquery);

        }catch(SQLException e){
            e.printStackTrace();
        }

            while(result.next()){
                String Student_Id=result.getString(1);
                String Student_Name=result.getString(2);
                String Father_Name=result.getString(3);
                String Class_No=result.getString(4);
                String Address=result.getString(5);
                String PhoneNo=result.getString(6);
              }

当Compiler到达Select Query的createStatement时。它给出了NullPointerException的异常，并且这两个代码都在同一个函数_JspService中。我在scriplet中写了这个来检查数据库连接。

这是我得到的例外。

＆＃34; org.apache.jasper.JasperException：处理JSP页面时发生异常第97行的/TestDatabase.jsp

97:stment=con.createStatement();

＆＃34; 根本原因

java.lang.NullPointerException
org.apache.jsp.TestDatabase_jsp._jspService(TestDatabase_jsp.java:166)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
org.apache.jasper.servlet.JspServletWrapper.service(JspServlet

＆＃34;

创建语句导致的异常

0 个答案: