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我是新到web開發到Java。我正在編寫這個基本的Java Web應用程序，它將把客戶信息存儲到數據庫中。我使用MVC-2架構。我的Jsp發送一個請求到一個servlet，它反過來試圖安裝一個bean並將該對象插入到數據庫中。 當我嘗試連接到數據庫（在調試模式下）連接變量返回空。所以數據不能被插入。無法連接到NetBeans Java Web應用程序中的mysql數據庫
這是說對數據庫連接類
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package customer;
import java.io.Serializable;
import java.sql.Connection;
import java.sql.DriverManager;
/**
*
* @author
*/
public class DatabaseOperations implements Serializable
{
private static Connection connection;
public DatabaseOperations()
{
try
{
String username = "root";
String password = "root";
String url = "jdbc:mysql://localhost/test";
Class.forName ("com.mysql.jdbc.Driver").newInstance();
connection = DriverManager.getConnection (url, username, password);
System.out.println("Database connection established");
}
catch(Exception e)
{
}
}
public static Connection getConnection()
{
return connection;
}
}
這是增加了客戶對數據庫的方法
public void addCustomer(CustomerBean customer) throws SQLException {
DatabaseOperations db = new DatabaseOperations();
connection = DatabaseOperations.getConnection();
statement = connection.createStatement();
String query = "insert into customer (name, address, phone, email) "
+ "values (" + customer.name + ","
+ customer.address + ","
+ customer.phone + ","
+ customer.email + "," + ")";
statement.executeUpdate(query);
}
，最終這就是我所說的方法，該servlet添加一個客戶
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package customer;
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;
import customer.CustomerBean;
import javax.servlet.RequestDispatcher;
/**
*
* @author
*/
public class CustomerServlet extends HttpServlet {
/**
* Processes requests for both HTTP
* <code>GET</code> and
* <code>POST</code> methods.
*
* @param request servlet request
* @param response servlet response
* @throws ServletException if a servlet-specific error occurs
* @throws IOException if an I/O error occurs
*/
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html;charset=UTF-8");
PrintWriter out = response.getWriter();
CustomerBean customer = new CustomerBean();
try {
out.println("tests");
customer.setName(request.getParameter("name"));
customer.setEmail(request.getParameter("email"));
customer.setAddress(request.getParameter("address"));
customer.setPhone(request.getParameter("phone"));
/************** ADD CUSTOMER TO DB HERE***********************/
customer.addCustomer(customer);
request.setAttribute("cust", customer);
request.getRequestDispatcher("/index.jsp").forward(request, response);
}
catch (Exception e)
{
e.printStackTrace();
}
}
另外我想指定我的netbeans IDE連接到mysql數據庫，因爲我可以創建表並從netbeans中的服務選項卡插入數據。 – mbass
您有問題嗎？或者你只是提交一份關於你當前開發工作的狀態報告？是否所有的代碼都與問題相關，或者您認爲它可能會縮小一點，例如，實際獲得數據庫連接的位置。有沒有辦法來測試這是否成功。是否顯示異常或錯誤消息，或者這只是「不能正常工作」。也許問題在於調用'getConnection'方法。這是一個靜態方法，還是一個實例方法？ （你是否應該調用'db'的getConnection方法）？ – spencer7593
我有問題。所有的代碼都與問題有關。 get連接方法是靜態的。我的問題在於，每當我安裝數據庫操作時，我都希望建立到數據庫的連接，並且我希望連接位於連接實例變量中。但它不在那裏。當我運行調試器時，它跳過語句「connection = DriverManager.getConnection（url，username，password）;」我想這是錯誤的來源 – mbass