Java连接MySql数据库的封装类

数据库封装类包含：连接数据库，更新，查询，是否有下一个，获取字段对应值，断开连接，get和set函数

可以说是非常完整的java操作数据库的一个封装类了，凡是涉及到数据库操作时，这个类用起来都非常方便。

DB.java

package javabean;

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;

public class DB {
    private String drv = "com.mysql.jdbc.Driver";//驱动
    private String url = "jdbc:mysql://localhost:3306/Stu_cou";//根据自己的数据库设定
    private String usr = "root";//用户名
    private String pwd = "root";//密码

    private Connection conn = null;
    private Statement stm = null;
    private ResultSet rs = null;
//连接数据库
    public boolean createConn() {
        boolean b = false;
        try {
            usr = "root";
            pwd = "root";
            Class.forName(drv).newInstance();
            conn = (Connection)DriverManager.getConnection(url, usr, pwd);
            b = true;
        } catch (SQLException e) {
        } catch (ClassNotFoundException e) {
        } catch (InstantiationException e) {
        } catch (IllegalAccessException e) {
        }
        return b;
    }
//数据库更新语句
    public boolean update(String sql) {
        boolean b = false;
        try {
            stm = (Statement)conn.createStatement();
            stm.execute(sql);
            b = true;
        } catch (Exception e) {
            System.out.println(e.toString());
        }
        return b;
    }
//查询语句
    public void query(String sql) {
        try {
            stm = (Statement)conn.createStatement();
            rs = stm.executeQuery(sql);
        } catch (Exception e) {
        }
    }
//是否有下一个    
    public boolean next() {
        boolean b = false;
        try {
            if(rs.next())b = true;
        } catch (Exception e) {
        }
        return b;        
    }
//得到字段对应的值    
    public String getValue(String field) {
        String value = "";
        try {
            if(rs!=null)value = rs.getString(field);
        } catch (Exception e) {
            e.printStackTrace();
        }
        if (value == null) value = "";
        return value;
    }
//断开连接
    public void close() {
        try {
            if (conn != null)
                conn.close();
            
        } catch (SQLException e) {
        }
        try {
            if (stm != null)
                stm.close();
        } catch (SQLException e) {
        }
        try {
            if (rs != null)
                rs.close();
        } catch (SQLException e) {
        }
    }

    public void closeConn() {
        try {
            if (conn != null)
                conn.close();
        } catch (SQLException e) {
        }
    }

    public void closeStm() {
        try {
            if (stm != null)
                stm.close();
        } catch (SQLException e) {
        }
    }

    public void closeRs() {
        try {
            if (rs != null)
                rs.close();
        } catch (SQLException e) {
        }
    }    
    
    
    
    
//get和set函数
    public Connection getConn() {
        return conn;
    }

    public void setConn(Connection conn) {
        this.conn = conn;
    }

    public String getDrv() {
        return drv;
    }

    public void setDrv(String drv) {
        this.drv = drv;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    public ResultSet getRs() {
        return rs;
    }

    public void setRs(ResultSet rs) {
        this.rs = rs;
    }

    public Statement getStm() {
        return stm;
    }

    public void setStm(Statement stm) {
        this.stm = stm;
    }

    public String getUrl() {
        return url;
    }

    public void setUrl(String url) {
        this.url = url;
    }

    public String getUsr() {
        return usr;
    }

    public void setUsr(String usr) {
        this.usr = usr;
    }
}

注意：这个非本人原创！

DBC.java

这是自己写的一个，增加了PreparedStatement

package com.common.db;

import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Connection;  
import java.sql.PreparedStatement;  
import java.sql.Statement;  
public class DBC {
    private static String driver = "com.mysql.jdbc.Driver";
    private static String url = "jdbc:mysql://localhost:3306/StaffRec";
    private static String username = "root";
    private static String password = "root";
    static {
        try {
            /**
             * 加载驱动
             */
            Class.forName(driver);
        }catch(Exception ex) {
            ex.printStackTrace();
        }
    }
    public static Connection getConnection() {
        /**
         * 创建连接对象
         */
        Connection conn=null;
        try {
            conn=(Connection) DriverManager.getConnection(url,username,password);
        }catch(Exception ex) {
            ex.printStackTrace();
        }
        return conn;
    }
    /**
     * 关闭相关流
     */
    public static void close(ResultSet rs,Statement st,Connection conn) {
        try {
            if(rs!=null) {
                rs.close();
            }
            if(st!=null) {
                st.close();
            }
            if(conn!=null) {
                conn.close();
            }
        }catch(SQLException e) {
            e.printStackTrace();
        }
    }
    public static void closePst(ResultSet rs,PreparedStatement pst,Connection conn) {
        try {
            if(rs!=null) {
                rs.close();
            }
            if(pst!=null) {
                pst.close();
            }
            if(conn!=null) {
                conn.close();
            }
        }catch(SQLException e) {
            e.printStackTrace();
        }
    }


}