JDBC之连接操作mysql数据库

一：引入mysql驱动：mysql-connector-java-5.0.8-bin.jar

二：在src下新增conf.properties配置文件，用于配置数据库的配置信息

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/jmt2017
username=root
password=root

三：新增JDBCUtils用于获取连接，关闭连接

import java.io.FileReader;
import java.io.IOException;
import java.sql.*;
import java.util.Properties;

public class JDBCUtils {

    private static String driver = null;
    private static String url = null;
    private static String username = null;
    private static String password = null;

    private JDBCUtils(){}

    private static void setProperties(){
        try {
            Properties properties = new Properties();
            properties.load(new FileReader("src/conf.properties"));
            driver = properties.getProperty("driver");
            url = properties.getProperty("url");
            username = properties.getProperty("username");
            password = properties.getProperty("password");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    static {
        setProperties();
        try {
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection(){
        try {
            return DriverManager.getConnection(url, username, password);
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }

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

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

}

四：执行sql语句，操作数据库：

①获取数据库连接Connection

Connection conn = JDBCUtils.getConnection();

②根据连接获取PreparedStatement执行对象

PreparedStatement ps = conn.prepareStatement("delete from users where id = ?");

③执行sql得到结果集

ResultSet resultSet = ps.executeQuery();

④解析结果

while (resultSet.next()){

 

resultSet.getString("id");

}

⑤关闭连接

JDBCUtils.closeResource(resultSet,ps,conn);

Connection conn = null;
PreparedStatement ps = null;
ResultSet resultSet = null;
try {
    conn = JDBCUtils.getConnection();
    ps = conn.prepareStatement("select * from users");
    resultSet = ps.executeQuery();
    while (resultSet.next()){
        String id = resultSet.getString("id");
        String name = resultSet.getString("name");
        String password = resultSet.getString("password");
        System.out.println(id+"..."+name+"...."+password);
    }
} catch (SQLException e) {
    e.printStackTrace();
}finally {
    JDBCUtils.closeResource(resultSet,ps,conn);
}