jsp中对MySql的增删查改操作

1.配置数据源与数据池

在Web应用程序中建立一个META-INF目录，在其中建立一个context.xml文件。

<?xml version="1.0" encoding="utf-8"?>
<Context reloadable = "true">
<Resource
      name="jdbc/sampleDS"                   //数据源名
      type="javax.sql.DataSource"            //指定该资源的类型
      maxActive="4"                          //同时活动连接实例的最大数
      maxIdle="2"                            //可空闲的最大连接数
      username="root"                        //数据库用户名
      maxWait="5000"                         //在没有可用连接的情况下，抛出异常前等待的最大毫秒数
      driverClassName="com.mysql.jdbc.Driver"  //使用的JDBC驱动程序完整的类名
      password="123"                          //数据库密码
      url="jdbc:mysql://localhost:3306/mydata"/>   //传递给JDBC驱动程序的数据库URL
</Context>

2.进行连接数据库，这里为什么要单独写一个文件呢？因为一般采用DAO模式设计，在这个模式中，数据库访问与应用程序中实现业务逻辑是分开的。

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;
import java.sql.*;

public class DBBean{
    Connection con;
    DataSource dataSource;

    public  DBBean() throws NamingException, SQLException {
        Context context = new InitialContext();
        dataSource = (DataSource)context.lookup("java:comp/env/jdbc/sampleDS");
        con = dataSource.getConnection();
    }

    public Connection getConnection() throws NamingException, SQLException {
        return con;
    }
}

3.实现数据的增添

Connection con = null;
ArrayList<student> students = (ArrayList<student>)request.getParameter("value"); //获取要插入的数据
student std = new student();                     //把表的数据放到student类里
try {
    DBBean dao = new DBBean();                   //链接数据库
    con = dao.getConnection();
} catch (NamingException e) {
    e.printStackTrace();
} catch (SQLException e) {
    e.printStackTrace();
}
String sql = "INSERT INTO student" + "(id, name, sex, major, hometown)VALUES(?,?,?,?,?)";
try(
    PreparedStatement pstmt = con.prepareStatement(sql)) {
        for(student std:students) {
        pstmt.setString(1, std.getId());
        pstmt.setString(2, std.getName());
        pstmt.setString(3, std.getSex());
        pstmt.setString(4, std.getMajor());
        pstmt.setString(5, std.getHometown());
        pstmt.executeUpdate();
    }
}
catch (SQLException e) {
    e.printStackTrace();
}

4.实现数据的删除

Connection con = null;
String s = (String)request.getParameter("value"); //要删除的数据的表的第一个值，同时也是主键
student std = new student();                     //把表的数据放到student类里
try {
    DBBean dao = new DBBean();                   //链接数据库
    con = dao.getConnection();
} catch (NamingException e) {
    e.printStackTrace();
} catch (SQLException e) {
    e.printStackTrace();
}
String sql = "DELETE FROM student where id = "+ s;
try(
    PreparedStatement pstmt = con.prepareStatement(sql)){
    pstmt.executeUpdate();
}catch(SQLException e) {
    e.printStackTrace();
}

5.实现数据的查找

Connection con = null;
try {
    DBBean dao = new DBBean();                   //链接数据库
    con = dao.getConnection();
} catch (NamingException e) {
    e.printStackTrace();
} catch (SQLException e) {
    e.printStackTrace();
}
ArrayList<student> stdList = new ArrayList();
String sql = "SELECT * FROM student";
try (
    PreparedStatement pstmt = con.prepareStatement(sql);
    ResultSet rst = pstmt.executeQuery()){
        while(rst.next()){
            student std = new student();
            std.setId(rst.getString("id"));
            std.setName(rst.getString("name"));
            std.setSex(rst.getString("sex"));
            std.setMajor(rst.getString("major"));
            std.setHometown(rst.getString("hometown"));
            stdList.add(std);
    }
}catch(SQLException e){
    e.printStackTrace();
}

嘿嘿，我知道你也想要单个的查找

Connection con = null;
String s = (String)request.getParameter("value"); //要查找的数据的表的第一个值，同时也是主键
student std = new student();                     //把表的数据放到student类里
try {
    DBBean dao = new DBBean();                   //链接数据库
    con = dao.getConnection();
} catch (NamingException e) {
    e.printStackTrace();
} catch (SQLException e) {
    e.printStackTrace();
}
String sql = "SELECT id,name,sex,major,hometown" +
        " FROM student WHERE id=?";
try(
    PreparedStatement pstmt = con.prepareStatement(sql)){
    pstmt.setString(1, s);
    try(ResultSet rst = pstmt.executeQuery()){
        if(rst.next()){
            std.setId(rst.getString("id"));
            std.setName(rst.getString("name"));
            std.setSex(rst.getString("sex"));
            std.setMajor(rst.getString("major"));
            std.setHometown(rst.getString("hometown"));
        }
    }
}catch(SQLException e) {
    e.printStackTrace();
}

6.实现数据的更新

Connection con = null;
String s = (String)request.getParameter("value"); //要修改的数据的表的第一个值，同时也是主键
student std = new student();                     //把表的数据放到student类里
try {
    DBBean dao = new DBBean();                   //链接数据库
    con = dao.getConnection();
} catch (NamingException e) {
    e.printStackTrace();
} catch (SQLException e) {
    e.printStackTrace();
}
String sql = "SELECT id,name,sex,major,hometown" +
        " FROM student WHERE id=?";
try(
    PreparedStatement pstmt = con.prepareStatement(sql, ResultSet.TYPE_SCROLL_SENSITIVE, CONCUR_UPDATABLE)){
    pstmt.setString(1, s);
    try(ResultSet rst = pstmt.executeQuery()){
        if(rst.next()){
            //rst.updateString(1, request.getParameter("id"));
            rst.updateString(2, request.getParameter("name"));
            rst.updateString(3, request.getParameter("sex"));
            rst.updateString(4, request.getParameter("major"));
            rst.updateString(5, request.getParameter("hometown"));
            rst.updateRow();
        }
    }
}catch(SQLException e) {
    e.printStackTrace();
}

怎么说呢，其实这些都应该封装到一个Dao文件，具体的操作看你自己啦