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  • rs.last()

    package com.runoob.test;

    import java.io.IOException;
    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;

    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;

    import sun.security.action.GetBooleanAction;

    /**
    * Servlet implementation class Login
    */
    @WebServlet("/Login")
    public class Login extends HttpServlet {
    private static final long serialVersionUID = 1L;


    //JDBC驱动器名称和数据库的URL
    static final String JDBC_DRIVER="com.microsoft.sqlserver.jdbc.SQLServerDriver";
    static final String DB_URL="jdbc:sqlserver://localhost:1433;DatabaseName=ReportServerTempDB";

    //数据库的凭据
    static final String USER="sa";
    static final String PASS="123457";

    private Statement stmt;
    private Connection conn;
    private ResultSet rs;
    /**
    * @see HttpServlet#HttpServlet()
    */
    public Login() {
    super();
    // TODO Auto-generated constructor stub
    }

    /**
    * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    //throw new ServletException("GET method used with " +
    //getClass( ).getName( )+": POST method required.");

    }

    /**
    * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
    */
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
    // TODO Auto-generated method stub
    //doGet(request,response);
    String site0 = request.getContextPath() + "/InPut.jsp";
    String site1 = new String("http://localhost:8080/Login/Login.jsp");
    String userId=request.getParameter("userId");
    String pass=request.getParameter("password");
    response.setContentType("text/html;charset=UTF-8");
    try{
    //注册JDBC驱动器
    Class.forName(JDBC_DRIVER);

    //打开一个连接
    conn = DriverManager.getConnection(DB_URL, USER, PASS);

    //执行SQL查询
    stmt = conn.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_READ_ONLY);
    String sql = "SELECT userId,password FROM Table_1 where userId ='" + userId +"' and password = '" + pass + "'";
    rs = stmt.executeQuery(sql);
    rs.last(); //定位到最后一行,即读出到最后一行,否则,计算不出来所有的行数

    int rowCount = rs.getRow();


    if(rowCount>0)
    {

    request.getSession().setAttribute("userInfo", userId);
    response.sendRedirect(site0);

    }
    else
    {
    response.sendRedirect(site1);

    }
    }
    catch(SQLException se){
    //处理JDBC错误
    se.printStackTrace();
    }
    catch(Exception e){
    //处理Class.forName错误
    e.printStackTrace();
    }
    finally{
    //最后是用于关闭资源的块
    try{
    if(stmt!=null)
    stmt.close();
    }
    catch(SQLException se2){

    }//我们不能做什么
    try {
    rs.close();
    } catch (SQLException e) {
    e.printStackTrace();
    }

    try{
    if(conn!=null)
    conn.close();
    }
    catch(SQLException se){
    se.printStackTrace();
    }//end finally try
    }//end try

    }

    }
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  • 原文地址:https://www.cnblogs.com/cyy-13/p/5780216.html
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