java - 使用 JSP 的数据库并收到错误

Question

我在尝试向数据库添加信息时创建的 JSP 文件存在问题。当我尝试执行并且它指向此代码块时，我不断收到 org.apache.jasper.JasperException: Exception in JSP: 错误。我假设它与 setAutoCommit 语句有关，但我不确定，因为它也显示了 nullPointerException。任何见解都会有所帮助。

<%@ page import="java.sql.*" %>

<%
    String url = "jdbc:mysql://example:3306/database";
    String username = "test";
    String password = "test";
    Connection conn = null;
    Statement stm=null;

    String classPath = "sun.jdbc.odbc.jdbc0dbcDriver";
    try{
        Class.forName(classPath);
        conn = DriverManager.getConnection(url,username,password);
        }catch(Exception exc){

            out.println(exc.toString());

        }

%>

<center><a href="example3-1.jsp">View Movies</a></center><br>
<%
    String MovieTitle=request.getParameter("MovieTitle");
    String MainActor=request.getParameter("MainActor");
    String MainActress=request.getParameter("MainActress");
    String Rating=request.getParameter("Rating");

    String query1 = null;

    query1 = "INSERT INTO MovieTitles (MovieTitle,MainActor,MainActress,Rating) VALUES('"+MovieTitle+"','"+MainActor+"','"+MainActress+"','"+Rating+"')";

    conn.setAutoCommit(false);
    stm = conn.createStatement();
    try{
        stm.executeUpdate(query1);
        conn.commit();
        out.println("<center><h2>A new movie has been added.</h2>");
        out.println("<a href=example3-2.jsp>Add another Movie</a></center>");
        }catch(Exception exc){
            conn.rollback();
            conn.setAutoCommit(true);
        %>

            <script>
                alert("Entry failed. Please retry.");
            </script>
    <%}%>
<%
    if(stm != null){ stm.close();}
    conn.close();
%>

Answer 1

//步骤:注册 JDBC 驱动程序

  Class.forName("com.mysql.jdbc.Driver");

//步骤:打开连接

conn=DriverManager.getConnection(DB_URL, USER, PASS);