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isuning
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【Flink1.14实战】Docker环境 DataStream jdbc

mysql source

从 MySQL 中读取数据的 Source。

首先 pom.xml 中添加 MySQL 依赖:

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<version>8.0.19</version>
</dependency>

数据库表

DROP TABLE IF EXISTS `book`;
CREATE TABLE book (
	id INT NOT NULL,
	title varchar(30),
	author varchar(30),
	price	   INT,
	PRIMARY KEY (id)
);

INSERT INTO `book` VALUES ('1', 'zhangsan', '123456', '18'), ('2', 'lishi', '123', '17'), ('3', 'wangwu', '1234', '18'), ('4', 'jam', '12345', '16');
COMMIT;

新建实体类:book.java

package quick.jdbc;

public class Book {

    private  int id;
    private String title;
    private String author;
    private int price;

    public Book(int id, String title, String author, int price) {
        this.id = id;
        this.title = title;
        this.author = author;
        this.price = price;
    }

    @Override
    public String toString() {
        return "Book{" +
                "id=" + id +
                ", title='" + title + '\'' +
                ", author='" + author + '\'' +
                ", price=" + price +
                '}';
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }

    public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }
}

新建 Source 类 SourceFromMySQL.java,该类继承 RichSourceFunction ,实现里面的 open、close、run、cancel 方法:

package quick.jdbc;

import org.apache.flink.configuration.Configuration;
import org.apache.flink.streaming.api.functions.source.RichSourceFunction;

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

public class SourceFromMySQL extends RichSourceFunction<Book> {

    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 book;";
        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<Book> ctx) throws Exception {
        ResultSet resultSet = ps.executeQuery();
        while (resultSet.next()) {
            Book book = new Book(
                    resultSet.getInt("id"),
                    resultSet.getString("title").trim(),
                    resultSet.getString("author").trim(),
                    resultSet.getInt("price"));
            ctx.collect(book);
        }
    }

    @Override
    public void cancel() {
    }

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

Flink 程序:

package quick.jdbc;

import org.apache.flink.streaming.api.environment.StreamExecutionEnvironment;

public class JdbcSourceExample {
    public static void main(String[] args) throws Exception {

        final StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();

        env.addSource(new SourceFromMySQL()).print();

        env.execute("jdbc source job");
    }
}

运行 Flink 程序,控制台日志中可以看见打印的 信息。

$ docker-compose logs -f taskmanager
taskmanager_1  | Book{id=0, title='title0', author='author0', price=50}
taskmanager_1  | Book{id=1, title='title1', author='author1', price=51}
taskmanager_1  | Book{id=2, title='title2', author='author2', price=52}
posted on 2022-05-01 22:16  吕布辕门  阅读(56)  评论(0)    收藏  举报
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