https://www.iteye.com/blog/lobin-2434012
语法
Expr1 ::= ‘for’ (‘(’ Enumerators ‘)’ | ‘{’ Enumerators ‘}’)
{nl} [‘yield’] Expr
Enumerators ::= Generator {semi Generator}
Generator ::= Pattern1 ‘<-’ Expr {[semi] Guard | semi Pattern1 ‘=’ Expr}
Guard ::= ‘if’ PostfixExpr
例子
ForTest.scala
object ForTest extends App {
var begin: Int = 1;
var end : Int = 10;
for (i <- begin until end)
println(i);
}
编译
>scalac -d classes ForTest.scala
执行
>scala ForTest
1
2
3
4
5
6
7
8
9
例子
ForTest2.scala
object ForTest2 extends App {
var begin: Int = 1;
var end : Int = 10;
for {i <- begin until end
j <- 1 until i}
println("(" + i + "," + j + ")");
}
编译
>scalac -d classes ForTest2.scala
执行
>scala ForTest2
(2,1)
(3,1)
(3,2)
(4,1)
(4,2)
(4,3)
(5,1)
(5,2)
(5,3)
(5,4)
(6,1)
(6,2)
(6,3)
(6,4)
(6,5)
(7,1)
(7,2)
(7,3)
(7,4)
(7,5)
(7,6)
(8,1)
(8,2)
(8,3)
(8,4)
(8,5)
(8,6)
(8,7)
(9,1)
(9,2)
(9,3)
(9,4)
(9,5)
(9,6)
(9,7)
(9,8)
例子
ForTest3.scala
object ForTest3 extends App {
var matrix = Array(1, 2, 3, 4, 5)
for (i <- matrix)
println(i);
}
编译
>scalac -d classes ForTest3.scala
执行
>scala ForTest3
1
2
3
4
5
例子
ForTest4.scala
object ForTest4 extends App {
var matrix = Array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
for (i <- matrix
if i % 2 == 0)
println(i);
}
编译
>scalac -d classes ForTest4.scala
执行
>scala ForTest4
2
4
6
8
10
scala currying
object CurryingTest {
def summary() {
println("---summary start---")
println("--- summary end ---")
}
def details() {
println("---start usage start---")
println("--- start usage end ---")
println("---restart usage start---")
println("--- restart usage end ---")
println("---stop usage start---")
println("--- stop usage end ---")
println("---status usage start---")
println("--- status usage end ---")
}
def usage[T](summary: => T)(details: => T): Unit = {
println("---usage start---")
summary
println("-----------------")
details
println("--- usage end ---")
}
def main(args: Array[String]) {
usage(summary())(details())
}
}
>scalac -d classes CurryingTest.scala
>scala CurryingTest
---usage start---
---summary start---
--- summary end ---
-----------------
---start usage start---
--- start usage end ---
---restart usage start---
--- restart usage end ---
---stop usage start---
--- stop usage end ---
---status usage start---
--- status usage end ---
--- usage end ---
object CurryingTest {
def summary() {
println("---summary start---")
println("--- summary end ---")
}
def details() {
println("---start usage start---")
println("--- start usage end ---")
println("---restart usage start---")
println("--- restart usage end ---")
println("---stop usage start---")
println("--- stop usage end ---")
println("---status usage start---")
println("--- status usage end ---")
}
def usage[T](summary: => T)(details: => T): Unit = {
println("---usage start---")
summary
println("-----------------")
details
println("--- usage end ---")
}
def main(args: Array[String]) {
usage(summary())(details())
println("=================")
usage(summary()) {
println("===start usage start===")
println("=== start usage end ===")
println("===restart usage start===")
println("=== restart usage end ===")
println("===stop usage start===")
println("=== stop usage end ===")
println("===status usage start===")
println("=== status usage end ===")
}
}
}
>scalac -d classes CurryingTest.scala
>scala CurryingTest
---usage start---
---summary start---
--- summary end ---
-----------------
---start usage start---
--- start usage end ---
---restart usage start---
--- restart usage end ---
---stop usage start---
--- stop usage end ---
---status usage start---
--- status usage end ---
--- usage end ---
=================
---usage start---
---summary start---
--- summary end ---
-----------------
===start usage start===
=== start usage end ===
===restart usage start===
=== restart usage end ===
===stop usage start===
=== stop usage end ===
===status usage start===
=== status usage end ===
--- usage end ---
scala currying-例子3
def swallow(log: (Object, Throwable) => Unit, action: => Unit) {
try {
action
} catch {
case e: Throwable => log(e.getMessage(), e)
}
}
scala break
import org.junit.{Before, BeforeClass, Test}
import org.scalatest.junit.JUnitSuite
import scala.util.control.{Breaks, ControlThrowable}
private class BreakControl extends ControlThrowable
object ScalaBreaksTest {
@BeforeClass
def _init : Unit = {
}
}
class ScalaBreaksTest extends JUnitSuite {
private val breakException = new BreakControl
def init : Unit = ScalaBreaksTest._init
@Before
def inittest() : Unit = {}
@Test
def test1() : Unit = {
var i: Int = 0
try {
while (i < 100) {
i = i + 1
if (i == 5) {
throw breakException
}
}
} catch {
case ex: BreakControl =>
if (ex ne breakException) throw ex
}
println(i)
assert (5 == i, "i must eq 5")
}
@Test
def test2() : Unit = {
val loop = new Breaks
var i: Int = 0
loop.breakable {
while (i < 100) {
i = i + 1
if (i == 5) {
loop.break
}
}
}
println(i)
assert (5 == i, "i must eq 5")
}
}
class TestClass(var arg1: Int, var arg2: Int) {
def init() = {
arg1 = 0;
arg2 = 2;
}
}
>scalac TestClass.scala
>javap -c TestClass
Compiled from "TestClass.scala"
public class TestClass {
public int arg1();
Code:
0: aload_0
1: getfield #14 // Field arg1:I
4: ireturn
public void arg1_$eq(int);
Code:
0: aload_0
1: iload_1
2: putfield #14 // Field arg1:I
5: return
public int arg2();
Code:
0: aload_0
1: getfield #21 // Field arg2:I
4: ireturn
public void arg2_$eq(int);
Code:
0: aload_0
1: iload_1
2: putfield #21 // Field arg2:I
5: return
public void init();
Code:
0: aload_0
1: iconst_0
2: invokevirtual #26 // Method arg1_$eq:(I)V
5: aload_0
6: iconst_2
7: invokevirtual #28 // Method arg2_$eq:(I)V
10: return
public TestClass(int, int);
Code:
0: aload_0
1: iload_1
2: putfield #14 // Field arg1:I
5: aload_0
6: iload_2
7: putfield #21 // Field arg2:I
10: aload_0
11: invokespecial #32 // Method java/lang/Object."<init>":()V
14: return
}
object Test {
def main(args: Array[String]) {
println("greet.")
}
}
>scalac Test.scala
编译后生成了2个class文件：Test.class，Test$.class，对应2个class：Test，Test$
>javap -c Test
Compiled from "Test.scala"
public final class Test {
public static void main(java.lang.String[]);
Code:
0: getstatic #16 // Field Test$.MODULE$:LTest$;
3: aload_0
4: invokevirtual #18 // Method Test$.main:([Ljava/lang/String;)V
7: return
}
>javap -c Test$
Compiled from "Test.scala"
public final class Test$ {
public static Test$ MODULE$;
public static {};
Code:
0: new #2 // class Test$
3: invokespecial #12 // Method "<init>":()V
6: return
public void main(java.lang.String[]);
Code:
0: getstatic #20 // Field scala/Predef$.MODULE$:Lscala/Predef$;
3: ldc #22 // String greet.
5: invokevirtual #26 // Method scala/Predef$.println:(Ljava/lang/Object;)V
8: return
}
class TestClass(var arg1: Int, var arg2: Int) {
def this() = {
this(0, 2);
}
def add() : Int = {
arg1 + arg2
}
}
object TestClassTest {
def main(args: Array[String]) = {
val testClass = new TestClass();
println("arg1: " + testClass.arg1 + ", arg2: " + testClass.arg2 + ", result: " + testClass.add());
testClass.arg1 = 100;
testClass.arg2 = 200;
println("arg1: " + testClass.arg1 + ", arg2: " + testClass.arg2 + ", result: " + testClass.add());
}
}
成员变量的隐式get&set方法。如上面的arg1，arg2，在类外部通过testClass.arg1 = 100;testClass.arg2 = 200;进行set,通过testClass.arg1;testClass.arg2进行get。
Java执行Scala脚本
public class Test {
private static Logger log = Logger.getLogger(Test.class);
private static ScriptEngine engine;
@BeforeClass
public static void init() {
engine = ScalaEngine.get();
}
public void test(String input) {
engine.put("input", input);
URL url = getClass().getResource("test.scala");
InputStream is = null;
try {
is = url.openStream();
} catch (IOException e) {
e.printStackTrace();
}
Reader reader = new InputStreamReader(is);
try {
Object result = engine.eval(reader);
System.out.println(result);
} catch (ScriptException e) {
e.printStackTrace();
}
}
@org.junit.Test
public void test() {
test("test");
test("not test");
}
}
test.scala
var _input = "test"
_input == input
public class ScalaEngine {
private static Logger log = Logger.getLogger(ScalaEngine.class);
private static ScriptEngine engine = init();
private static ScriptEngine init() {
ScriptEngineManager sem = new ScriptEngineManager();
ScriptEngine engine = sem.getEngineByName("scala");
if (engine instanceof IMain) {
IMain entry = (IMain) engine;
ISettings isettings = entry.isettings();
Settings settings = entry.settings();
MutableSettings.BooleanSetting setting = null;
try {
setting = (MutableSettings.BooleanSetting) field(settings, "usejavacp");
log.info("usejavacp: " + setting.v());
if (! setting.v()) {
field(setting, "v", true, MutableSettings.BooleanSetting.class);
}
setting = (MutableSettings.BooleanSetting) field(settings, "usejavacp");
log.info("usejavacp: " + setting.v());
} catch (IllegalAccessException e) {
log.warn(e.getMessage(), e);
}
}
return engine;
}
public static ScriptEngine get() {
return engine;
}
public static Object field(Object o, String fieldName, Class<?> klass) throws IllegalAccessException {
Field valueOps = null;
try {
valueOps = klass.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
throw new IllegalAccessException(e.getMessage());
}
valueOps.setAccessible(true);
return valueOps.get(o);
}
public static Object field(Object o, String fieldName) throws IllegalAccessException {
Class<?> klass = o.getClass();
while (klass != Object.class) {
Class<?> parent = klass.getSuperclass();
Object value = null;
try {
value = field(o, fieldName, klass);
} catch(IllegalAccessException e) {
log.info("field " + fieldName + " of " + klass.getName() + " not found, would trying " + parent.getName());
}
if (value != null) {
return value;
}
klass = parent;
}
throw new IllegalAccessException("field " + fieldName + " not found");
}
public static void field(Object o, String fieldName, Object value, Class<?> klass) throws IllegalAccessException {
Field valueOps = null;
try {
valueOps = klass.getDeclaredField(fieldName);
} catch (NoSuchFieldException e) {
throw new IllegalAccessException(e.getMessage());
}
valueOps.setAccessible(true);
valueOps.set(o, value);
}
}
scala JUnitSuite for unit test
import org.junit.{Before, BeforeClass, Test}
import org.scalatest.junit.JUnitSuite
import scala.util.control.{Breaks, ControlThrowable}
import scala.util.control.Breaks._
private class BreakControl extends ControlThrowable
object BreaksTest {
@BeforeClass
def _init : Unit = {
}
}
class BreaksTest extends JUnitSuite {
private val breakException = new BreakControl
def init : Unit = BreaksTest._init
@Before
def inittest() : Unit = {}
@Test
def test1() : Unit = {
var i: Int = 0
breakable {
while (i < 100) {
i = i + 1
if (i == 5) {
break // break()
}
}
}
println(i)
assert (5 == i, "i must eq 5")
}
@Test
def test2() : Unit = {
val loop = new Breaks
var i: Int = 0
loop.breakable {
while (i < 100) {
i = i + 1
if (i == 5) {
loop.break
}
}
}
println(i)
assert (5 == i, "i must eq 5")
}
@Test
def test3() : Unit = {
var i: Int = 0
try {
while (i < 100) {
i = i + 1
if (i == 5) {
throw breakException
}
}
} catch {
case ex: BreakControl =>
if (ex ne breakException) throw ex
}
println(i)
assert (5 == i, "i must eq 5")
}
}
import java.util
import java.util.Map
import com.shenma.kafka.MessageListener
import org.junit.{Before, BeforeClass, Test}
import org.scalatest.junit.JUnitSuite
object KafkaConsumerTransportTest {
private var consumerProperties : Map[String, Object] = null
@BeforeClass
def _init : Unit = {
consumerProperties = new util.HashMap[String, Object]
consumerProperties.put("bootstrap.servers", "192.16.10.44:9092")
consumerProperties.put("group.id", "test")
consumerProperties.put("enable.auto.commit", "false")
consumerProperties.put("retries", "10")
consumerProperties.put("auto.commit.interval.ms", "1000")
consumerProperties.put("session.timeout.ms", "15000")
consumerProperties.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")
consumerProperties.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer")
}
}
class KafkaConsumerTransportTest extends JUnitSuite {
def init : Unit = KafkaConsumerTransportTest._init
@Before
def inittest() : Unit = {}
@Test
def test() : Unit = {
var messageListener : MessageListener[String, String] = new TestMagentCatMessageListener()
var transport : KafkaConsumerTransport[String, String] =
new KafkaConsumerTransport[String, String](KafkaConsumerTransportTest.consumerProperties, util.Arrays.asList("topic-2018-0925"), messageListener)
transport run()
// for test
try {
this.synchronized {
wait()
}
} catch {
case e: InterruptedException => {
println(e)
e.printStackTrace()
}
}
}
}
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