package com.thinker.sql;

import com.thinker.model.Student;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
import org.apache.flink.streaming.api.functions.source.SourceFunction;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;

/**
 * @author zeekling [lingzhaohui@zeekling.cn]
 * @version 1.0
 * @apiNote
 * @since 2020-05-05
 */
public class SourceFromMySQL extends RichSourceFunction<Student> {


    private PreparedStatement ps;
    private Connection connection;

    /**
     * open() 方法中建立连接，这样不用每次 invoke 的时候都要建立连接和释放连接。
     *
     * @param parameters
     * @throws Exception
     */
    @Override
    public void open(Configuration parameters) throws Exception {
        super.open(parameters);
        connection = getConnection();
        String sql = "select * from Student;";
        ps = this.connection.prepareStatement(sql);
    }

    /**
     * 程序执行完毕就可以进行，关闭连接和释放资源的动作了
     *
     * @throws Exception
     */
    @Override
    public void close() throws Exception {
        super.close();
        if (connection != null) { //关闭连接和释放资源
            connection.close();
        }
        if (ps != null) {
            ps.close();
        }
    }

    /**
     * DataStream 调用一次 run() 方法用来获取数据
     *
     * @param ctx
     * @throws Exception
     */
    @Override
    public void run(SourceContext<Student> ctx) throws Exception {
        ResultSet resultSet = ps.executeQuery();
        while (resultSet.next()) {
            Student student = new Student(
                    resultSet.getInt("id"),
                    resultSet.getString("name").trim(),
                    resultSet.getString("password").trim(),
                    resultSet.getInt("age"));
            ctx.collect(student);
        }
    }

    @Override
    public void cancel() {
    }

    private static Connection getConnection() {
        Connection con = null;
        try {
            Class.forName("com.mysql.jdbc.Driver");
            con = DriverManager.getConnection("jdbc:mysql://localhost:3306/flink_test?useUnicode=true&characterEncoding=UTF-8", "root", "123456");
        } catch (Exception e) {
            System.out.println("-----------mysql get connection has exception , msg = "+ e.getMessage());
        }
        return con;
    }
}