JDBC连接整个过程

1.导入驱动(放在lib下)

connector-java-5.0.8-bin.jar

2.导入配置文件(放在src下)

jdbc.properties

driverClass=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/数据库名称
user=用户名
password=密码

3.修改配置文件
4.导入工具类(放在utils包下)

JdbcUtils.java

package utils;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ResourceBundle;

public class JdbcUtils {
    static final String DRIVERCLASS;
    static final String URL;
    static final String USER;
    static final String PASSWORD;

    static {
        // 获取ResourceBundle
        ResourceBundle bundle = ResourceBundle.getBundle("jdbc");

        // 获取指定的内容
        DRIVERCLASS = bundle.getString("driverClass");
        URL = bundle.getString("url");
        USER = bundle.getString("user");
        PASSWORD = bundle.getString("password");
    }

    static {
        // 注册驱动
        try {
            Class.forName(DRIVERCLASS);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    // 获取连接
    public static Connection getConnection() throws SQLException {
        // 获取连接
        return  DriverManager.getConnection(URL, USER, PASSWORD);
    }

    /**
     * 释放资源
     *
     * @param conn
     *            连接
     * @param st
     *            语句执行者
     * @param rs
     *            结果集
     */
    public static void closeResource(Connection conn, Statement st, ResultSet rs) {
        closeResultSet(rs);
        closeStatement(st);
        closeConn(conn);
    }

    /**
     * 释放连接
     *
     * @param conn
     *            连接
     */
    public static void closeConn(Connection conn) {
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            conn = null;
        }

    }

    /**
     * 释放语句执行者
     *
     * @param st
     *            语句执行者
     */
    public static void closeStatement(Statement st) {
        if (st != null) {
            try {
                st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            st = null;
        }

    }

    /**
     * 释放结果集
     *
     * @param rs
     *            结果集
     */
    public static void closeResultSet(ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
            rs = null;
        }

    }
}

5.在DAO层编写代码

        Connection conn = null ;
        PreparedStatement st = null ;
        ResultSet  rs = null ;

        try {
            //获取连接
            conn = JdbcUtils.getConnection();

            //编写sql
            String sql = "" ;

            //获取语句执行者
            st = conn.prepareStatement(sql);

            //设置参数

            //执行sql
            st.executeUpdate();

            //处理结果
            //rs = st.executeQuery()
            //int i = st.executeUpdate();

        } catch (SQLException e) {
            e.printStackTrace();
            throw e;
        }finally{
            JdbcUtils.closeResource(conn, st, rs);
        }