MySQL数据库如何实现与JavaWeb项目连接

MySQL数据库如何实现与JavaWeb项目连接？针对这个问题，这篇文章详细介绍了相对应的分析和解答，希望可以帮助更多想解决这个问题的小伙伴找到更简单易行的方法。

创新互联基于分布式IDC数据中心构建的平台为众多户提供西部信息机房四川大带宽租用成都机柜租用成都服务器租用。

数据库是编程中重要的一部分，它囊括了数据操作，数据持久化等各方面。在每一门编程语言中都占有相当大的比例。

本次，我以MySQL为例，使用MVC编程思想(请参阅我之前的博客)。简单演示一下JavaWeb对数据库的操作。

1：我们需要掌握简单的SQL语句，并且会简单操作图形化的数据库。我们在数据库建一个表(Users)可以在里面随便添加几条数据。

MySQL数据库如何实现与JavaWeb项目连接

2：接下来，我们获得驱动并连接到MySQL。

package com.joker.web.db; 
import java.sql.Connection; 
import java.sql.DriverManager; 
import java.sql.SQLException; 
public class DBConnection { 
  private static Connection con = null; 
  // 驱动程序名 
  private static String driverName = "com.mysql.jdbc.Driver"; 
  // 数据库用户名 
  private static String userName = "root"; 
  // 密码 1 
  private static String userPasswd = "*****"; 
  // 数据库名 
  private static String dbName = "jokertest"; 
  // 联结字符串 
  private static String url = "jdbc:mysql://localhost/" + dbName + "?user=" 
      + userName + "&password=" + userPasswd 
      + "&useUnicode=true&characterEncoding=gbk"; 
  public static Connection getConnection() { 
    try { 
      // 1.驱动 
      Class.forName(driverName); 
      // 2. 连接数据库 保持连接 
      con = DriverManager.getConnection(url); 
    } catch (ClassNotFoundException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } 
    return con; 
  } 
  public static void closeConnection() { 
    if (con != null) { 
      try { 
        con.close(); 
      } catch (SQLException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
    } 
  } 
}

3.写我们的Dao文件,即对数据库的增删改查

package com.joker.web.dao; 
import java.sql.*; 
import java.util.*; 
import com.joker.web.db.DBConnection; 
import com.joker.web.entity.User; 
public class UserDao { 
  // 查找所有数据，返回List集合 
  public List selectAll() { 
    Connection con = DBConnection.getConnection();// 连接数据库 保持连接 
    Statement stmt; 
    List list = new ArrayList(); 
    try { 
      stmt = con.createStatement();// 执行SQL语句 
      ResultSet rs = stmt.executeQuery("SELECT * FROM users");// 查找 
                                  // 数据返回结果集 
      while (rs.next()) { 
        User user = new User(); 
        user.setId(rs.getInt("id")); 
        user.setUserName(rs.getString("USER_NAME")); 
        user.setDisplayName(rs.getString("DISPLAY_NAME")); 
        user.setPwd(rs.getString("PWD")); 
        list.add(user); 
      } 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      DBConnection.closeConnection(); 
    } 
    return list; 
  } 
  // 按条件查找 
  // where USER_NAME='"+ name + "' and PWD='" + pwd + "' 
  public User selectWhere(String whereOption) { 
    Connection con = DBConnection.getConnection();// 连接数据库 保持连接 
    Statement stmt; 
    User user = null; 
    try { 
      stmt = con.createStatement();// 执行SQL语句 
      String sql = "SELECT * FROM users "; 
      if (!whereOption.equals("")) { 
        sql += whereOption; 
      } 
      // 查找数据返回结果集 
      ResultSet rs = stmt.executeQuery(sql); 
      while (rs.next()) { 
        user = new User(); 
        user.setUserName(rs.getString("USER_NAME")); 
        user.setDisplayName(rs.getString("DISPLAY_NAME")); 
        user.setPwd(rs.getString("PWD")); 
      } 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      DBConnection.closeConnection(); 
    } 
    return user; 
  } 
  // 新增 
  public int insert(User user) { 
    Connection con = DBConnection.getConnection(); 
    PreparedStatement pstmt = null; 
    String sql = " insert into users(user_name,pwd,display_name) values(?,?,?)"; 
    // 增加用prepareStatement 
    int count = 0; 
    try { 
      pstmt = con.prepareStatement(sql); 
      pstmt.setString(1, user.getUserName()); 
      pstmt.setString(2, user.getPwd()); 
      pstmt.setString(3, user.getDisplayName()); 
      count = pstmt.executeUpdate(); 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      try { 
        pstmt.close(); 
      } catch (SQLException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
      DBConnection.closeConnection(); 
    } 
    return count; 
  } 
  // 修改 
  public int upDate(User user) { 
    Connection con = DBConnection.getConnection(); 
    PreparedStatement pstmt = null; 
    String sql = " update users " + " set user_name = ? , " + " pwd = ? , " 
        + " display_name= ? " + " where id= ? "; 
    int count = 0; 
    try { 
      pstmt = con.prepareStatement(sql); 
      pstmt.setString(1, user.getUserName()); 
      pstmt.setString(2, user.getPwd()); 
      pstmt.setString(3, user.getDisplayName()); 
      pstmt.setInt(4, user.getId()); 
      count = pstmt.executeUpdate(); 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      try { 
        pstmt.close(); 
      } catch (SQLException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
      DBConnection.closeConnection(); 
    } 
    return count; 
  } 
  // 删除 
  public int delete(int id) { 
    Connection con = DBConnection.getConnection(); 
    PreparedStatement pstmt = null; 
    String sql = " delete from users where id = ?"; 
    int count = 0; 
    try { 
      pstmt = con.prepareStatement(sql); 
      pstmt.setInt(1, id); 
      count = pstmt.executeUpdate(); 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      try { 
        pstmt.close(); 
      } catch (SQLException e) { 
        // TODO Auto-generated catch block 
        e.printStackTrace(); 
      } 
      DBConnection.closeConnection(); 
    } 
    return count; 
  } 
  public List selectPage(int from, int rows) { 
    Connection con = DBConnection.getConnection();// 连接数据库 保持连接 
    Statement stmt; 
    List list = new ArrayList(); 
    try { 
      stmt = con.createStatement();// 执行SQL语句 
      ResultSet rs = stmt.executeQuery("SELECT * FROM users LIMIT " 
          + from + "," + rows); 
      while (rs.next()) { 
        User user = new User(); 
        user.setId(rs.getInt("id")); 
        user.setUserName(rs.getString("USER_NAME")); 
        user.setDisplayName(rs.getString("DISPLAY_NAME")); 
        user.setPwd(rs.getString("PWD")); 
        list.add(user); 
      } 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      DBConnection.closeConnection(); 
    } 
    return list; 
  } 
// 返回所有数剧条数 
  public int selectCount() { 
    Connection con = DBConnection.getConnection();// 连接数据库 保持连接 
    Statement stmt; 
    int count =0 ; 
    try { 
      stmt = con.createStatement();// 执行SQL语句 
      ResultSet rs = stmt.executeQuery("SELECT count(1) count FROM users"); 
      while (rs.next()) { 
        count = rs.getInt("count"); 
      } 
    } catch (SQLException e) { 
      // TODO Auto-generated catch block 
      e.printStackTrace(); 
    } finally { 
      DBConnection.closeConnection(); 
    } 
    return count; 
  } 
}

4.使用Servlet当控制器，在Servlet对网页上的数据进行操作。

package com.joker.web.servlet; 
import java.io.IOException; 
import java.io.PrintWriter; 
import java.util.*; 
import javax.servlet.ServletException; 
import javax.servlet.http.HttpServlet; 
import javax.servlet.http.HttpServletRequest; 
import javax.servlet.http.HttpServletResponse; 
import net.sf.json.JSONArray; 
import net.sf.json.JSONObject; 
import com.joker.web.dao.UserDao; 
import com.joker.web.entity.User; 
public class UserServlet extends HttpServlet { 
  /** 
   * Constructor of the object. 
   */ 
  public UserServlet() { 
    super(); 
  } 
  /** 
   * Destruction of the servlet. 
 
   */ 
  public void destroy() { 
    super.destroy(); // Just puts "destroy" string in log 
    // Put your code here 
  } 
  public void doGet(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
    this.doPost(request, response); 
  } 
  public void doPost(HttpServletRequest request, HttpServletResponse response) 
      throws ServletException, IOException { 
    request.setCharacterEncoding("utf-8"); 
    response.setContentType("text/html;charset=utf-8"); 
    String action = request.getParameter("action"); 
    if (action.equals("select")) { 
      select(request, response); 
    } else if (action.equals("update")) { 
      update(request, response); 
    } else if (action.equals("add")) { 
      insert(request, response); 
    } else if (action.equals("delete")) { 
      delete(request, response); 
    } 
  } 
  // 新增 
  private void insert(HttpServletRequest request, HttpServletResponse response)  
      throws IOException { 
    String uName = request.getParameter("userName"); 
    String pwd = request.getParameter("user"); 
    String dName = request.getParameter("displayName"); 
    User user = new User(); 
    user.setUserName(uName); 
    user.setPwd(pwd); 
    user.setDisplayName(dName); 
    UserDao uDao = new UserDao(); 
    int affCount = uDao.insert(user); 
    PrintWriter out = response.getWriter(); 
    // 将受影响数据的数量返回给jsp 
    out.print(affCount); 
  } 
  // 删除 
  private void delete(HttpServletRequest request, HttpServletResponse response) 
      throws IOException { 
    String[] ids = request.getParameterValues("uid[]"); 
    UserDao ud = new UserDao(); 
    int count = 0; 
    for (int i = 0; i < ids.length; i++) { 
      count += ud.delete(Integer.parseInt(ids[i])); 
    } 
    PrintWriter out = response.getWriter(); 
    out.print(count); 
  } 
  /** 
   * Initialization of the servlet. 
 
   * 
   * @throws ServletException 
   *       if an error occurs 
   */ 
  public void init() throws ServletException { 
    System.out.println("处室执行！！！！！！！！！！！！！！！"); 
  } 
  // 查询 
  public void select(HttpServletRequest request, HttpServletResponse response) 
      throws IOException { 
    String page = request.getParameter("page"); 
    String rows = request.getParameter("rows"); 
    System.out.println("page:" + page + " rows:" + rows); 
    UserDao ud = new UserDao(); 
    int rowsCount = Integer.parseInt(rows); 
    int from = (Integer.parseInt(page) - 1) * rowsCount; 
    List list = ud.selectPage(from, rowsCount); 
    HashMap map = new HashMap(); 
    map.put("total", ud.selectCount()); 
    map.put("rows", list); 
    // JSONArray ja = JSONArray.fromObject(list); 
    JSONObject jo = JSONObject.fromObject(map);// 单条数据 
    PrintWriter out = response.getWriter(); 
    System.out.println(jo.toString()); 
    // 将json数据返回给jspData-grid的url。 
    out.println(jo.toString()); 
  } 
  // 修改 
  public void update(HttpServletRequest request, HttpServletResponse response) 
      throws IOException { 
    String id = request.getParameter("id"); 
    String uName = request.getParameter("userName"); 
    String pwd = request.getParameter("pwd"); 
    String dName = request.getParameter("displayName"); 
    User user = new User(); 
    user.setId(Integer.parseInt(id)); 
    user.setUserName(uName); 
    user.setPwd(pwd); 
    user.setDisplayName(dName); 
    UserDao uDao = new UserDao(); 
    int affCount = uDao.upDate(user); 
    PrintWriter out = response.getWriter(); 
    // 将受影响数据的数量返回给jsp 
    out.print(affCount); 
  } 
}

5.使用Easy-UI框架，是数据库内容在页面进行显示

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%> 
<% 
  String path = request.getContextPath(); 
  String basePath = request.getScheme() + "://" 
      + request.getServerName() + ":" + request.getServerPort() 
      + path + "/"; 
%> 
 
 
 
 
 
main.jsp 
 
 
 
 
 
 
 
 
  <%-- ${sessionScope.user.userName} 
  ${sessionScope.user.dislayName} --%>

6.各个操作具体图片:

6.1添加:添加（张三 666 学生这条数据）默认显示五条数据

MySQL数据库如何实现与JavaWeb项目连接