JDBC

package jdbc;

import java.sql.*;

public final class JdbcUtils {
    private static String url = "jdbc:mysql://localhost:3306/jdbc";
    private static String user = "root";
    private static String password = "xxxxx";

    private JdbcUtils() {
    }

    static {
        try {
            Class.forName("com.mysql.jdbc.Driver");
        } catch (ClassNotFoundException e) {
            throw new ExceptionInInitializerError(e);
        }
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    public static void free(ResultSet rs, Statement st, Connection conn) {
        try {
            if (rs != null)
                rs.close();
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            try {
                if (st != null)
                    st.close();
            } catch (SQLException e) {
                e.printStackTrace();
            } finally {
                if (conn != null) {
                    try {
                        conn.close();
                    } catch (SQLException e) {
                        e.printStackTrace();
                    }
                }
            }
        }
    }
}

package jdbc;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class CRUD {
    public static void main(String[] args) throws SQLException {
        create();
    }

    static void delete() throws SQLException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "delete from user where id > 4 ";
            int res = st.executeUpdate(sql);
            System.out.println("res= " + res);

        } finally {
            JdbcUtils.free(rs, st, conn);
        }
    }

    static void update() throws SQLException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "update user set money=money+10 ";
            int res = st.executeUpdate(sql);
            System.out.println("res= " + res);

        } finally {
            JdbcUtils.free(rs, st, conn);
        }
    }

    static void create() throws SQLException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            String sql = "insert into user(name,birthday,money) values(‘name1‘,‘1987-01-01‘,400)";
            int res = st.executeUpdate(sql);
            System.out.println("res= " + res);

        } finally {
            JdbcUtils.free(rs, st, conn);
        }
    }


    static void read() throws SQLException {
        Connection conn = null;
        Statement st = null;
        ResultSet rs = null;
        try {
            conn = JdbcUtils.getConnection();
            st = conn.createStatement();
            rs = st.executeQuery("select id,name,birthday,money from user ");
            while (rs.next()) {
                System.out.println(rs.getObject("id") + "\t" + rs.getObject("name") + "\t" +
                        rs.getObject("birthday") + "\t" + rs.getObject("money"));
            }
        } finally {
            JdbcUtils.free(rs, st, conn);
        }
    }

}