spark mysql讀取寫入

 https://blog.csdn.net/zuochang_liu/article/details/97398209

SparkSession ss = SparkSession.builder().config(conf).enableHiveSupport().getOrCreate()
//讀取方式1
String sql = "(select * from xxx) as tmp; //注意這裏的sql格式，該sql也可以直接是一個表名
Dataset<Row> df = session.read().format("jdbc")
                    .option("url", jdbcURL)
                    .option("driver", driver)
                    .option("dbtable", sql)
                    .option("user", username)
                    .option("password", password)
                    .load();
//讀取方式2：
Properties connectionProperties = new Properties();
            connectionProperties.put("user", username);
            connectionProperties.put("password", password);
            connectionProperties.put("driver", driver);
                 session.read().jdbc(url, table, properties)
df = session.read().jdbc(jdbcURL,sql,connectionProperties);


//寫入方式1：
String saveMode = "Overwrite";
df.write().mode(saveMode).jdbc(jdbcURL, tablename, connectionProperties);
//寫入方式2：
final String sql = "insert into tab_xxx (c1,c2,c3) values(?,?,?)";

    df.javaRDD().foreachPartition(new VoidFunction<Iterator<Row>>() {
        private static final long serialVersionUID = -834520661839866305L;
        @Override
        public void call(Iterator<Row> t) throws Exception {
            Class.forName(driver);
            Connection conn = (Connection) DriverManager.getConnection(url, username, password);
            conn.setAutoCommit(false);
            try {
                PreparedStatement pstmt = (PreparedStatement) conn.prepareStatement(sql);
                int loop = 0;
                while (t.hasNext()) {
                    Row row = t.next();
                    for (int i = 0; i < 3; i++) { //這裏的3是插入的列只有3列
                        pstmt.setObject(i + 1, row.get(i));
                    }
                    pstmt.executeUpdate();
                    if (++loop % 1000 == 0) {
                        conn.commit();
                    }
                }
                conn.commit();
                pstmt.close();
            } finally {
                conn.close();
            }
        }
    });
}