wordcount

sc.textFile("../data/data.txt").flatMap(_.split(" ")).map((_,1)).reduceByKey(_+_).collect

spark-sql

/*
 读取json 文件 并通过sql 执行 join 查询
*/ 
public static void main(String[] args) {
        SparkSession session = SparkSession.builder().master("local")
                .appName("master").getOrCreate();
        Dataset<Row> df = session.read().json("./data/user2.json");
//        json.show();
        df.createOrReplaceTempView("user");

        Dataset<Row> df2 = session.read().json("./data/dept.json");
        df2.createOrReplaceTempView("dept");
        Dataset<Row> result = session.sql("select u.id,u.name,d.name dname from user u left join dept d" +
                " on u.deptno= d.id" +
                "");
//        result.show();
//        result.collectAsList().forEach(System.out::println);
       result.write().csv("data/result2");
       session.close();
    }

/*
 jdbc  导出csv
*/ 
public static void main(String[] args) {
        SparkSession session = SparkSession.builder().master("local")
                .appName("master").getOrCreate();
        Properties connectionProperties = new Properties();
        connectionProperties.put("user", "root");
        connectionProperties.put("password", "root");
        Long start = System.currentTimeMillis();
        Dataset<Row> report = session.read().jdbc("jdbc:mysql://localhost:3306/test",
                "idms_user", connectionProperties).filter("createDate is not null");

        report.write().option("header", true).mode("overwrite").csv("data/idms_user");
        long end = System.currentTimeMillis();
        System.out.println("cost:" + (end - start)+"ms");
        session.close();
    }

 /*
 jdbc  通过sql 查询  函数处理
*/ 
public static void main(String[] args) {
        SparkSession session = SparkSession.builder().master("local")
                .appName("master").getOrCreate();
        Properties connectionProperties = new Properties();
        connectionProperties.put("user", "root");
        connectionProperties.put("password", "root");
        Long start = System.currentTimeMillis();
        Dataset<Row> report = session.read().jdbc("jdbc:mysql://localhost:3306/test",
                "report", connectionProperties);
        report.createOrReplaceTempView("report");

        Dataset<Row> result = session.
                sql("select id,date_format(created_at,'yyyy-MM-dd') createDate ,title " +
                        " , date_format(now(),'yyyy-MM-dd') nowDate" +
                        " ,datediff(now(),created_at) days"+
                        " from report where age>12");

        result.show();
        session.close();
    }