探索Scala编程案例:深入9.scala源码解析

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资源摘要信息:"9.scala.zip文件提供了关于Scala编程语言的一个实际案例。Scala是一种结合了面向对象编程和函数式编程的多范式编程语言,被设计为能够无缝地支持JVM(Java虚拟机)和.NET平台。该文件仅包含一个名为'9.scala'的文件,意味着可能包含了一个与Scala语言相关的实例程序或代码片段,用于演示如何在Scala环境中实现特定的功能或算法。 Scala编程语言的核心概念和知识点包括: 1. 基本语法:Scala的语法简洁,但包含丰富的特性。它具有表达性强的类型系统,允许变量声明为可变或不可变。例如,使用`val`关键字声明不可变变量,而`var`关键字用于声明可变变量。 2. 面向对象编程:Scala支持所有Java支持的面向对象编程特性,如继承、多态和封装。此外,Scala的类可以轻易地扩展以支持混入(mixins)功能,这允许开发者创建可重用的代码组件。 3. 函数式编程:Scala为函数式编程提供了强大的支持,包括高阶函数、递归、模式匹配、偏应用函数和匿名函数等。函数是Scala中的第一类公民,可以作为参数传递,也可以作为结果返回。 4. 集合框架:Scala提供了一个功能强大的集合库,包括列表(List)、集(Set)、映射(Map)等。集合框架提供了大量方法用于处理和转换数据,支持延迟计算。 5. 并发编程:Scala使用actors模型进行并发编程,该模型可以避免传统的多线程编程中的锁竞争和死锁问题。actors通过消息传递机制相互交互,提高了并发程序的可伸缩性和可靠性。 6. Scala的类型系统:Scala拥有一个复杂的类型系统,支持泛型、特质(Traits)、抽象类型成员等高级类型特性。它还支持隐式转换和隐式参数,使得类型转换和方法调用更加灵活。 7. Scala与Java的互操作性:Scala完全兼容Java,这意味着Scala程序可以直接调用任何Java库,同时Java代码也可以轻松地与Scala代码混合使用。这一特点使得Scala用户可以充分利用现有的Java生态系统。 8. Scala的构建工具:Scala项目通常使用sbt(Simple Build Tool)或Maven来构建。这些构建工具能够处理依赖管理、编译代码、运行测试和打包应用程序等任务。 9.scala文件可能包含的是一个具体的Scala代码示例,该代码可能涉及到上述的某些或全部概念,用以展示Scala如何在实际中应用这些编程范式和特性。用户可以将该文件解压并使用Scala编译器或IDE(如IntelliJ IDEA或Eclipse)来加载和运行代码,以此来学习Scala编程的具体实践。 由于文件名'9.scala'直接表示了这是一个案例,它很可能是某个教程或课程中的第九个教学示例,可能是针对初学者或是具有一定编程背景的开发者来理解和实践Scala编程语言的某一特定功能或概念。" 在实际使用中,用户可以打开'9.scala'文件进行学习和实验,深入理解Scala语言的应用场景和解决实际问题的能力。对于学习Scala的开发者而言,实践和案例分析是掌握该语言的关键步骤。

2023-06-02 23:12:37 WARN NativeCodeLoader:60 - Unable to load native-hadoop library for your platform... using builtin-java classes where applicable Setting default log level to "WARN". To adjust logging level use sc.setLogLevel(newLevel). For SparkR, use setLogLevel(newLevel). Traceback (most recent call last): File "mysqlTest.py", line 12, in <module> jdbcDF=spark.read.format("jdbc").option("url","jdbc:mysql://localhost:3306/sparktest?useSSL=false").option("driver","com.mysql.cj.jdbc.Driver").option("dbtable","employee").option("user", "root").option("password", "123456").load() File "/usr/local/spark/python/pyspark/sql/readwriter.py", line 172, in load return self._df(self._jreader.load()) File "/usr/local/spark/python/lib/py4j-0.10.7-src.zip/py4j/java_gateway.py", line 1257, in __call__ File "/usr/local/spark/python/pyspark/sql/utils.py", line 63, in deco return f(*a, **kw) File "/usr/local/spark/python/lib/py4j-0.10.7-src.zip/py4j/protocol.py", line 328, in get_return_value py4j.protocol.Py4JJavaError: An error occurred while calling o31.load. : java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) at org.apache.spark.sql.execution.datasources.jdbc.DriverRegistry$.register(DriverRegistry.scala:45) at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions$$anonfun$5.apply(JDBCOptions.scala:99) at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions$$anonfun$5.apply(JDBCOptions.scala:99) at scala.Option.foreach(Option.scala:257) at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions.<init>(JDBCOptions.scala:99) at org.apache.spark.sql.execution.datasources.jdbc.JDBCOptions.<init>(JDBCOptions.scala:35) at org.apache.spark.sql.execution.datasources.jdbc.JdbcRelationProvider.createRelation(JdbcRelationProvider.scala:32) at org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:318) at org.apache.spark.sql.DataFrameReader.loadV1Source(DataFrameReader.scala:223) at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:211) at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:167) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244) at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357) at py4j.Gateway.invoke(Gateway.java:282) at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132) at py4j.commands.CallCommand.execute(CallCommand.java:79) at py4j.GatewayConnection.run(GatewayConnection.java:238) at java.lang.Thread.run(Thread.java:748)

2023-06-03 上传

org.apache.spark.api.python.PythonException: Traceback (most recent call last): File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/python/lib/pyspark.zip/pyspark/worker.py", line 830, in main process() File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/python/lib/pyspark.zip/pyspark/worker.py", line 820, in process out_iter = func(split_index, iterator) File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/rdd.py", line 5405, in pipeline_func return func(split, prev_func(split, iterator)) File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/rdd.py", line 5405, in pipeline_func return func(split, prev_func(split, iterator)) File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/rdd.py", line 828, in func return f(iterator) File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/rdd.py", line 3964, in combineLocally merger.mergeValues(iterator) File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/python/lib/pyspark.zip/pyspark/shuffle.py", line 256, in mergeValues for k, v in iterator: File "/Users/zzs/PycharmProjects/pythonProject/venv/lib/python3.10/site-packages/pyspark/python/lib/pyspark.zip/pyspark/util.py", line 81, in wrapper return f(*args, **kwargs) File "/Users/zzs/PycharmProjects/pythonProject/pyspark项目练习/项目练习2.py", line 7, in <lambda> json_str_file = file_rdd.flatMap(lambda x: x.spilt("|")) AttributeError: 'str' object has no attribute 'spilt' at org.apache.spark.api.python.BasePythonRunner$ReaderIterator.handlePythonException(PythonRunner.scala:561) at org.apache.spark.api.python.PythonRunner$$anon$3.read(PythonRunner.scala:767) at org.apache.spark.api.python.PythonRunner$$anon$3.read(PythonRunner.scala:749) at org.apache.spark.api.python.BasePythonRun

2023-07-20 上传