• JDBC 更新信息

    ListStu:

    1）链接删除信息的Servlet:

    "<a href='/JDBC01/ListOne?id="+id+"'>修改 </a></td>"
    package case01;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Date;

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


@WebServlet("/ListStu")
public class ListStu extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    
    public ListStu() {
        super();
        
    }

    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset = utf-8");
        PrintWriter out = response.getWriter();
        
        Connection conn = null;
        Statement state = null;
        ResultSet rs = null;
        
        // mysql 数据库驱动程序的加载
        try {
            // 加载，固定的语句
            Class.forName("com.mysql.jdbc.Driver");
            out.print("数据库驱动程序加载成功！");
            
            //数据库连接
            String url = "jdbc:mysql://127.0.0.1:3306/test";
            String user = "root";
            String password = "zzgzzg";
            conn = DriverManager.getConnection(url, user, password);
            
            out.print("<br>"+"数据库连接成功！");
            
            // 数据库访问并获取结果
            state = conn.createStatement();
            // sql 语句
            String sql = "select id,name,sex,birthday from student";
            rs = state.executeQuery(sql);
            
            // 画表
            out.print("<table border=1>");
            // 表头
            out.print("<tr>"
                    +"<td>id</td>"
                    +"<td>name</td>"
                    +"<td>sex</td>"
                    +"<td>birthday</td>"
                    +"<td>操作</td>"
                    + "</tr>");
            
            // 循环获取字段数据并输出
            while(rs.next()) {
                int id = rs.getInt(1); // 获取第一个字段,id
                String name = rs.getString("name"); // 获取名字
                String sex = rs.getString("sex");
                Date birthday = rs.getDate("birthday");
                
                // 表内容
                // 利用<a>标签连接删除、修改的Servlet
                out.print("<tr>"
                        +"<td>"+id+"</td>"
                        +"<td>"+name+"</td>"
                        +"<td>"+sex+"</td>"
                        +"<td>"+birthday+"</td>"
                        +"<td>"
                        + "<a href='/JDBC01/DropStu?id="+id+"'>删除</a>&nbsp;"
                        + "<a href='/JDBC01/ListOne?id="+id+"'>修改 </a></td>"
                        + "</tr>");
            }
            
            out.print("</table>");
            out.print("<br>"+"数据库访问成功！");
            
        } catch (ClassNotFoundException e) {
            
            e.printStackTrace();
            out.print("数据库驱动程序加载失败！");
            
        } catch (SQLException e) {
            
            e.printStackTrace();
            out.print("数据库连接失败！");
        }finally {
            // 回收资源
            // 回收 conn
            if(conn!=null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                conn = null;
            }
            // 回收state
            if(state!=null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                state = null;
            }
            // 回收 rs
            if(rs!=null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                rs = null;
            }
            
        }
            
    }

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

}

    ListOne:

    1）根据 id 寻找位置并执行 sql 语句

    // 根据 id 寻找位置并执行 sql 语句
            int id = Integer.parseInt(request.getParameter("id"));
            String sql = "select id,sequence,name,sex,birthday from student where id = ?";
            PreparedStatement prep = conn.prepareStatement(sql);
            prep.setInt(1, id);
            rs = prep.executeQuery();

    2）表单 action 属性值为：UpdateStu的绝对位置

    "<form action='/JDBC01/UpdateStu' method='post'>"
    package case01;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Date;

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


@WebServlet("/ListOne")
public class ListOne extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    
    public ListOne() {
        super();
        
    }

    
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset = utf-8");
        PrintWriter out = response.getWriter();
        
        Connection conn = null;
        Statement state = null;
        ResultSet rs = null;
        
        // mysql 数据库驱动程序的加载
        try {
            // 加载，固定的语句
            Class.forName("com.mysql.jdbc.Driver");
            out.print("数据库驱动程序加载成功！");
            
            //数据库连接
            String url = "jdbc:mysql://127.0.0.1:3306/test";
            String user = "root";
            String password = "zzgzzg";
            conn = DriverManager.getConnection(url, user, password);
            
            out.print("<br>"+"数据库连接成功！");
            
            int id = Integer.parseInt(request.getParameter("id"));
            
            // sql 语句
            String sql = "select id,sequence,name,sex,birthday from student where id = ?";
            
            // 数据库访问并获取结果
            PreparedStatement prep = conn.prepareStatement(sql);
            prep.setInt(1, id);
            rs = prep.executeQuery();
            
            
            // 循环获取字段数据并输出
            if(rs.next()) {
//                int id = rs.getInt(1); // 获取第一个字段,id
                String sequence = rs.getString("sequence");
                String name = rs.getString("name"); // 获取名字
                String sex = rs.getString("sex");
                Date birthday = rs.getDate("birthday");
                
                out.print("<form action='/JDBC01/UpdateStu' method='post'>");
                out.print("<p>"
                        +"<label>学号：</label>"
                        + "<input type='text' name='sequence' value="+sequence+">"
                        + "</p>");
                
                out.print("<p>"
                        +"<label>姓名：</label>"
                        + "<input type='text' name='name' value="+name+">"
                        + "</p>");
                
                out.print("<p>"
                        +"<label>性别：</label>"
                        + "<input type='text' name='sex' value="+sex+">"
                        + "</p>");
                
                out.print("<p>"
                        +"<label>日期：</label>"
                        + "<input type='text' name='birthday' value="+birthday+">"
                        + "</p>");
                out.print("<input type='hidden' name='id' value="+id+"></input>");
                out.print("<button type='submit'>提交</button>");
                out.print("</form>");
            }
//            out.print("<br>"+"数据库访问成功！");
            
        } catch (ClassNotFoundException e) {
            
            e.printStackTrace();
            out.print("数据库驱动程序加载失败！");
            
        } catch (SQLException e) {
            
            e.printStackTrace();
            out.print("数据库连接失败！");
        }finally {
            // 回收资源
            // 回收 conn
            if(conn!=null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                conn = null;
            }
            // 回收state
            if(state!=null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                state = null;
            }
            // 回收 rs
            if(rs!=null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                rs = null;
            }
            
        }
            
    }

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

}

    UpdataStu:

    1）信息修改：

                // 数据库修改
            String sql = "update student set sequence=?,name=?,sex=? where id=?";
            PreparedStatement prep = conn.prepareStatement(sql);
            prep.setString(1, sequence);
            prep.setString(2, name);
            prep.setString(3, sex);
            prep.setInt(4, id);
            prep.executeUpdate();
            
            //重定向
            response.sendRedirect("ListStu");
    package case01;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Date;

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


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

    public UpdateStu() {
        super();
        
    }


    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset = utf-8");
        PrintWriter out = response.getWriter();
        
        Connection conn = null;
        Statement state = null;
        ResultSet rs = null;
        
        // mysql 数据库驱动程序的加载
        try {
            // 固定的语句
            Class.forName("com.mysql.jdbc.Driver");
            out.print("数据库驱动程序加载成功！");
            
            //数据库连接
            String url = "jdbc:mysql://127.0.0.1:3306/test";
            String user = "root";
            String password = "zzgzzg";
            conn = DriverManager.getConnection(url, user, password);
            out.print("<br>"+"数据库连接成功！");
            
            
            // 获得来自前端的参数
            int id = Integer.parseInt(request.getParameter("id"));
            String sequence = request.getParameter("sequence");
            String name = request.getParameter("name");
            String sex = request.getParameter("sex");
            String birthday = request.getParameter("birthday");
            out.print("<br>"+name+sex+birthday);
            
            // 数据库访问
            String sql = "update student set sequence=?,name=?,sex=? where id=?";
            PreparedStatement prep = conn.prepareStatement(sql);
            prep.setString(1, sequence);
            prep.setString(2, name);
            prep.setString(3, sex);
            prep.setInt(4, id);
            prep.executeUpdate();
            
            //重定向
            response.sendRedirect("ListStu");
            
            out.print("<br>"+"学生信息添加成功！");
        }catch(Exception e) {
            e.printStackTrace();
            out.print("<br>"+"数据库访问失败！");
        }finally {
            // 回收资源
            // 回收 conn
            if(conn!=null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                conn = null;
            }
            // 回收state
            if(state!=null) {
                try {
                    state.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                state = null;
            }
            // 回收 rs
            if(rs!=null) {
                try {
                    rs.close();
                } catch (SQLException e) {
                    e.printStackTrace();
                }
                rs = null;
            }
            
        }
    }


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

}

    整体效果：

    修改前：

    修改时界面：

    修改后：
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  • 原文地址：https://www.cnblogs.com/ZZG-GANGAN/p/13967253.html
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