spark写数据到Mysql

1、使用c3p0

这个主要是因为c3p0实现了序列化，这样就可以直接传输到Worker上

ComboPooledDataSource

这个类主要是用来做生成数据库连接实例的，让它传到Worker上就可以直接使用了

2、业务代码

获取datasource

def getC3p0DateSource(filename:String,config:String): ComboPooledDataSource ={ 
val dataSource : ComboPooledDataSource = new ComboPooledDataSource(true)  
val conf = FileUtils.readJsonFile2Prop(filename,config) 
dataSource.setJdbcUrl(conf.getProperty("url")) 
dataSource.setDriverClass(conf.getProperty("driverClassName")) 
dataSource.setUser(conf.getProperty("username")) 
dataSource.setPassword(conf.getProperty("password")) 
dataSource.setMaxPoolSize(Integer.valueOf(conf.getProperty("maxPoolSize")))
dataSource.setMinPoolSize(Integer.valueOf(conf.getProperty("minPoolSize"))) 
dataSource.setAcquireIncrement(Integer.valueOf(conf.getProperty("acquireIncrement"))) 
dataSource.setInitialPoolSize(Integer.valueOf(conf.getProperty("initialPoolSize")))
dataSource.setMaxIdleTime(Integer.valueOf(conf.getProperty("maxIdleTime")))
dataSource
}

注意这里的InitialPoolSize不能太大

.foreachPartition(it=>{ 
val conn = comboPooledDataSource.getConnection  
val statement = conn.prepareStatement("insert into tb_eventclass_min values (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)") 
conn.setAutoCommit(false) 
it.foreach(x=>{ 
statement.setString(1,UUID.randomUUID().toString) 
statement.setLong(2,x._1._1.toString.toLong) 
statement.setLong(3,x._1._2.toString.toLong)
statement.setString(4,x._1._3.toString)  
statement.setString(5,x._1._4.toString) 
statement.setString(6,x._1._5.toString) 
statement.setString(7,x._1._6.toString) 
statement.setString(8,x._1._7.toString) 
statement.setString(9,x._1._8.toString)
statement.setLong(10,x._2)    
statement.setShort(11,x._1._10.toString.toShort) 
statement.setLong(12,x._1._9/60000L)
val calendar = Calendar.getInstance()
calendar.setTime(new Date(x._1._9)) 
val year = calendar.get(Calendar.YEAR) 
val month = calendar.get(Calendar.MONTH)+1
val day = calendar.get(Calendar.DAY_OF_MONTH)
val hour = calendar.get(Calendar.HOUR_OF_DAY) 
val min = calendar.get(Calendar.MINUTE) 
statement.setInt(13,year) 
statement.setInt(14,month) 
statement.setInt(15,day) 
statement.setInt(16,hour) 
statement.setInt(17,min) 
statement.addBatch()
}) 
try {
statement.executeBatch()conn.commit()
    
}catch { 
case e:Exception=>e.printStackTrace()
    
}finally { 
statement.close()
conn.close()
    
}})

在这里有四个注意点：

1、使用foreachPartition算子，减少数据库连接

这样dataSource.getConnection生成的连接和partition数量是一直的（不会很多）

2、使用批量插入，提高效率

这里要注意要开启批量插入
在数据库连接的URl后面加上 rewriteBatchedStatements=true (启动批处理操作)

String dbUrl =  "jdbc:mysql://localhost:3306/User? rewriteBatchedStatements=true";

3、关闭自动提交，防止死锁

conn.setAutoCommit(false)

4、在执行结束时要将statement和connect关闭

statement会一直增加消耗内存 connect归还到资源池中