Question

我的目标是从servlet将数据插入数据库。在这里我尝试过： 1）创建了一个简单的servlet，我在其中创建了连接数据并将数据插入mysql数据库的dbconnect。

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class logic extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        String name = request.getParameter("name");
        dbconnect con = new dbconnect();
        try (PrintWriter out = response.getWriter()) {
            /* TODO output your page here. You may use following sample code. */
            out.println("<!DOCTYPE html>");
            out.println("<html>");
            out.println("<head>");
            out.println("<title>Servlet logic</title>");            
            out.println("</head>");
            out.println("<body>");
            out.println("<h1>Servlet logic at " + request.getContextPath() + "</h1>");
            out.println("</body>");
            out.println("</html>");
        }
    }

    // <editor-fold defaultstate="collapsed" desc="HttpServlet methods. Click on the + sign on the left to edit the code.">
    /**
     * Handles the HTTP <code>GET</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Handles the HTTP <code>POST</code> method.
     *
     * @param request servlet request
     * @param response servlet response
     * @throws ServletException if a servlet-specific error occurs
     * @throws IOException if an I/O error occurs
     */
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

    /**
     * Returns a short description of the servlet.
     *
     * @return a String containing servlet description
     */
    @Override
    public String getServletInfo() {
        return "Short description";
    }// </editor-fold>

}

2）dbconnect类：

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.Statement;


public class dbconnect {
    Connection conn;
    Statement stm;

    public dbconnect(){
    try{
        conn = DriverManager.getConnection("jdbc:mysql://villaikalto.ge/villaika_type?user=villaika_type&password=pass");
        stm = conn.createStatement();
        System.out.println("success");
        String sql = "INSERT INTO users (mail, pass, gender, saxeli) VALUES (?, ?, ?, ?)";
        System.out.println("1");
        PreparedStatement statement = conn.prepareStatement(sql);
        System.out.println("2");
        statement.setString(1, "tsogiaidze");
        statement.setString(2, "nika");
        statement.setString(3, "nika");
        statement.setString(4, "kaci");
        System.out.println("3");
        int rowsInserted = statement.executeUpdate();
        System.out.println("4");
        if (rowsInserted > 0) {
        System.out.println("A new user was inserted successfully!");
        }
      }  
      catch (Exception ex){
          System.out.println("error");
          System.out.println(ex.getMessage());
      }
}
}

问题是，当我使用简单的java类创建dbconnect对象时，主方法数据已成功写入数据库，但是当我尝试从servlet创建dbconnect对象时，它不会向数据库添加数据。我使用netbeans并在类路径中添加了mysql驱动程序。附： servlet由JSP文件调用，它将一些html表单参数传递给servlet。

我想我的问题很明确，希望看到你的意见。

Answer 1

谁在我的问题上写了负面反馈？

如果这个问题愚蠢或不合适，为什么他不能回答呢？

经过7个小时的思考和尝试后，我找到了解决方案，我会写下来，以便将来有人也能解决这个问题。

因此dbconnect类适用于简单的java类而不是servlet的原因是simple.Simple类自动注册jdbc驱动程序（在本例中为mysql驱动程序）与java应用程序但servlet没有。因此我只需要编写在开始连接到数据库的这一行代码：

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

Answer 2

您好我的代码工作正常我尝试了这个

public class Dbconnect {
    Connection conn;

    public Dbconnect(){
        try{
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/test", "root", "welcome");
            String sql = "INSERT INTO student(student_id,student_name,class) VALUES(?,?,?)";
            PreparedStatement statement = conn.prepareStatement(sql);
            statement.setInt(1, 7);
            statement.setString(2, "nika1");
            statement.setString(3, "nika");
            int rowsInserted = statement.executeUpdate();
            if (rowsInserted > 0) {
                System.out.println("A new user was inserted successfully!");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }

    }
}

servlet-class：

public class Logic extends HttpServlet {

    protected void processRequest(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        String name = request.getParameter("name");
        Dbconnect con = new Dbconnect();
        try {
            PrintWriter out = response.getWriter();
            out.println("Inserted..");
        }
        catch (Exception e)
        {}
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        processRequest(request, response);
    }

}

在web.xml中：

    <servlet>
        <servlet-name>s1</servlet-name>
        <servlet-class>main.myPack.Logic</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>s1</servlet-name>
        <url-pattern>/logic</url-pattern>
    </servlet-mapping>

从servlet向mysql数据库添加数据

2 个答案: