面向对象

class Outer3 {
    private String privateStr = 'some string'

    def startThread() {
        new Thread(new Runnable() {      (1)
            void run() {
                println "${privateStr}."
            }
        }).start()                       (2)
    }
}

abstract class Abstract {         (1)
    String name

    abstract def abstractMethod() (2)

    def concreteMethod() {
        println 'concrete'
    }
}

class PersonConstructor {
    String name
    Integer age

    PersonConstructor(name, age) {          (1)
        this.name = name
        this.age = age
    }
}

def person1 = new PersonConstructor('Marie', 1)  (2)
def person2 = ['Marie', 2] as PersonConstructor  (3)
PersonConstructor person3 = ['Marie', 3]         (4)

class PersonWOConstructor {                                  (1)
    String name
    Integer age
}

def person4 = new PersonWOConstructor()                      (2)
def person5 = new PersonWOConstructor(name: 'Marie')         (3)
def person6 = new PersonWOConstructor(age: 1)                (4)
def person7 = new PersonWOConstructor(name: 'Marie', age: 2) (5)

def someMethod() { 'method called' }                           (1)
String anotherMethod() { 'another method called' }             (2)
def thirdMethod(param1) { "$param1 passed" }                   (3)
static String fourthMethod(String param1) { "$param1 passed" } (4)

def foo(Map args) { "${args.name}: ${args.age}" }
foo(name: 'Marie', age: 1)

def foo(String par1, Integer par2 = 1) { [name: par1, age: par2] }
assert foo('Marie').age == 1

def baz(a = 'a', int b, c = 'c', boolean d, e = 'e') { "$a $b $c $d $e" }

assert baz(42, true) == 'a 42 c true e'
assert baz('A', 42, true) == 'A 42 c true e'
assert baz('A', 42, 'C', true) == 'A 42 C true e'
assert baz('A', 42, 'C', true, 'E') == 'A 42 C true E'

def foo(Object... args) { args.length }
assert foo() == 0
assert foo(1) == 1
assert foo(1, 2) == 2

def foo(Object[] args) { args.length }
assert foo() == 0
assert foo(1) == 1
assert foo(1, 2) == 2

def foo(Object... args) { args }
assert foo(null) == null

def foo(Object... args) { args }
Integer[] ints = [1, 2]
assert foo(ints) == [1, 2]

def foo(Object... args) { 1 }
def foo(Object x) { 2 }
assert foo() == 1
assert foo(1) == 2
assert foo(1, 2) == 1

def method(Object o1, Object o2) { 'o/o' }
def method(Integer i, String  s) { 'i/s' }
def method(String  s, Integer i) { 's/i' }

assert method('foo', 42) == 's/i'

List<List<Object>> pairs = [['foo', 1], [2, 'bar'], [3, 4]]
assert pairs.collect { a, b -> method(a, b) } == ['s/i', 'i/s', 'o/o']

def method(Date d, Object o) { 'd/o' }
def method(Object o, String s) { 'o/s' }

def ex = shouldFail {
    println method(new Date(), 'baz')
}
assert ex.message.contains('Ambiguous method overloading')

assert method(new Date(), (Object)'baz') == 'd/o'
assert method((Object)new Date(), 'baz') == 'o/s'

def badRead() {
    new File('doesNotExist.txt').text
}

shouldFail(FileNotFoundException) {
    badRead()
}

def badRead() throws FileNotFoundException {
    new File('doesNotExist.txt').text
}

shouldFail(FileNotFoundException) {
    badRead()
}

class Data {
    private int id                                  (1)
    protected String description                    (2)
    public static final boolean DEBUG = false       (3)
}

class Data {
    private String id = IDGenerator.next() (1)
    // ...
}

class BadPractice {
    private mapping                         (1)
}
class GoodPractice {
    private Map<String,String> mapping      (2)
}

class Person {
    String name                             (1)
    int age                                 (2)
}

class Person {
    final String name                   (1)
    final int age                       (2)
    Person(String name, int age) {
        this.name = name                (3)
        this.age = age                  (4)
    }
}

class Person {
    String name
    void name(String name) {
        this.name = "Wonder $name"      (1)
    }
    String title() {
        this.name                       (2)
    }
}
def p = new Person()
p.name = 'Diana'                        (3)
assert p.name == 'Diana'                (4)
p.name('Woman')                         (5)
assert p.title() == 'Wonder Woman'      (6)

class Person {
    String name
    int age
}
def p = new Person()
assert p.properties.keySet().containsAll(['name','age'])

class PseudoProperties {
    // a pseudo property "name"
    void setName(String name) {}
    String getName() {}

    // a pseudo read-only property "age"
    int getAge() { 42 }

    // a pseudo write-only property "groovy"
    void setGroovy(boolean groovy) {  }
}
def p = new PseudoProperties()
p.name = 'Foo'                      (1)
assert p.age == 42                  (2)
p.groovy = true                     (3)

@SomeAnnotation                 (1)
void someMethod() {
    // ...
}

@SomeAnnotation                 (2)
class SomeClass {}

@SomeAnnotation String var      (3)

import java.lang.annotation.ElementType
import java.lang.annotation.Target

@Target([ElementType.METHOD, ElementType.TYPE])     (1)
@interface SomeAnnotation {}                        (2)

@interface Page {
    int statusCode()
}

@Page(statusCode=404)
void notFound() {
    // ...
}

@interface Page {
    String value()
    int statusCode() default 200
}

@Page(value='/home')                    (1)
void home() {
    // ...
}

@Page('/users')                         (2)
void userList() {
    // ...
}

@Page(value='error',statusCode=404)     (3)
void notFound() {
    // ...
}

import java.lang.annotation.Retention
import java.lang.annotation.RetentionPolicy

@Retention(RetentionPolicy.SOURCE)                   (1)
@interface SomeAnnotation {}                         (2)

class Tasks {
    Set result = []
    void alwaysExecuted() {
        result << 1
    }
    @OnlyIf({ jdk>=6 })
    void supportedOnlyInJDK6() {
        result << 'JDK 6'
    }
    @OnlyIf({ jdk>=7 && windows })
    void requiresJDK7AndWindows() {
        result << 'JDK 7 Windows'
    }
}

@Retention(RetentionPolicy.RUNTIME)
@interface OnlyIf {
    Class value()                    (1)
}

class Runner {
    static <T> T run(Class<T> taskClass) {
        def tasks = taskClass.newInstance()                                         (1)
        def params = [jdk: 6, windows: false]                                       (2)
        tasks.class.declaredMethods.each { m ->                                     (3)
            if (Modifier.isPublic(m.modifiers) && m.parameterTypes.length == 0) {   (4)
                def onlyIf = m.getAnnotation(OnlyIf)                                (5)
                if (onlyIf) {
                    Closure cl = onlyIf.value().newInstance(tasks,tasks)            (6)
                    cl.delegate = params                                            (7)
                    if (cl()) {                                                     (8)
                        m.invoke(tasks)                                             (9)
                    }
                } else {
                    m.invoke(tasks)                                                 (10)
                }
            }
        }
        tasks                                                                       (11)
    }
}

def tasks = Runner.run(Tasks)
assert tasks.result == [1, 'JDK 6'] as Set

@Service
@Transactional
class MyTransactionalService {}

@TransactionalService                           (1)
class MyTransactionalService {}

import groovy.transform.AnnotationCollector

@Service                                        (1)
@Transactional                                  (2)
@AnnotationCollector                            (3)
@interface TransactionalService {
}

def annotations = MyTransactionalService.annotations*.annotationType()
assert (Service in annotations)
assert (Transactional in annotations)

@Timeout(after=3600)
@Dangerous(type='explosive')

@Timeout(after=3600)
@Dangerous(type='explosive')
@AnnotationCollector
public @interface Explosive {}

@Explosive(after=0)                 (1)
class Bomb {}

@Retention(RetentionPolicy.RUNTIME)
public @interface Foo {
   String value()                                   (1)
}
@Retention(RetentionPolicy.RUNTIME)
public @interface Bar {
    String value()                                  (2)
}

@Foo
@Bar
@AnnotationCollector
public @interface FooBar {}                         (3)

@Foo('a')
@Bar('b')
class Bob {}                                        (4)

assert Bob.getAnnotation(Foo).value() == 'a'        (5)
println Bob.getAnnotation(Bar).value() == 'b'       (6)

@FooBar('a')
class Joe {}                                        (7)
assert Joe.getAnnotation(Foo).value() == 'a'        (8)
println Joe.getAnnotation(Bar).value() == 'a'       (9)

@CompileStatic(TypeCheckingMode.SKIP)
@AnnotationCollector
public @interface CompileDynamic {}

@AnnotationCollector(processor = "org.codehaus.groovy.transform.CompileDynamicProcessor")
public @interface CompileDynamic {
}

@CompileStatic                                                                  (1)
class CompileDynamicProcessor extends AnnotationCollectorTransform {            (2)
    private static final ClassNode CS_NODE = ClassHelper.make(CompileStatic)    (3)
    private static final ClassNode TC_NODE = ClassHelper.make(TypeCheckingMode) (4)

    List<AnnotationNode> visit(AnnotationNode collector,                        (5)
                               AnnotationNode aliasAnnotationUsage,             (6)
                               AnnotatedNode aliasAnnotated,                    (7)
                               SourceUnit source) {                             (8)
        def node = new AnnotationNode(CS_NODE)                                  (9)
        def enumRef = new PropertyExpression(
            new ClassExpression(TC_NODE), "SKIP")                               (10)
        node.addMember("value", enumRef)                                        (11)
        Collections.singletonList(node)                                         (12)
    }
}

trait FlyingAbility {                           (1)
        String fly() { "I'm flying!" }          (2)
}

trait Greetable {
    abstract String name()                              (1)
    String greeting() { "Hello, ${name()}!" }           (2)
}

class Person implements Greetable {                     (1)
    String name() { 'Bob' }                             (2)
}

def p = new Person()
assert p.greeting() == 'Hello, Bob!'                    (3)

trait Greeter {
    private String greetingMessage() {                      (1)
        'Hello from a private method!'
    }
    String greet() {
        def m = greetingMessage()                           (2)
        println m
        m
    }
}
class GreetingMachine implements Greeter {}                 (3)
def g = new GreetingMachine()
assert g.greet() == "Hello from a private method!"          (4)
try {
    assert g.greetingMessage()                              (5)
} catch (MissingMethodException e) {
    println "greetingMessage is private in trait"
}

trait Counter {
    private int count = 0                   (1)
    int count() { count += 1; count }       (2)
}
class Foo implements Counter {}             (3)
def f = new Foo()
assert f.count() == 1                       (4)
assert f.count() == 2

trait Named {
    public String name                      (1)
}
class Person implements Named {}            (2)
def p = new Person()                        (3)
p.Named__name = 'Bob'                       (4)

String my_package_Foo__bar

trait Named {
    String name                                     (1)
}
trait Polite extends Named {                        (2)
    String introduce() { "Hello, I am $name" }      (3)
}
class Person implements Polite {}
def p = new Person(name: 'Alice')                   (4)
assert p.introduce() == 'Hello, I am Alice'         (5)

trait WithId {                                      (1)
    Long id
}
trait WithName {                                    (2)
    String name
}
trait Identified implements WithId, WithName {}     (3)

trait SpeakingDuck {
    String speak() { quack() }                      (1)
}
class Duck implements SpeakingDuck {
    String methodMissing(String name, args) {
        "${name.capitalize()}!"                     (2)
    }
}
def d = new Duck()
assert d.speak() == 'Quack!'                        (3)

trait DynamicObject {                               (1)
    private Map props = [:]
    def methodMissing(String name, args) {
        name.toUpperCase()
    }
    def propertyMissing(String name) {
        props.get(name)
    }
    void setProperty(String name, Object value) {
        props.put(name, value)
    }
}

class Dynamic implements DynamicObject {
    String existingProperty = 'ok'                  (2)
    String existingMethod() { 'ok' }                (3)
}
def d = new Dynamic()
assert d.existingProperty == 'ok'                   (4)
assert d.foo == null                                (5)
d.foo = 'bar'                                       (6)
assert d.foo == 'bar'                               (7)
assert d.existingMethod() == 'ok'                   (8)
assert d.someMethod() == 'SOMEMETHOD'               (9)

trait A {
    String exec() { 'A' }               (1)
}
trait B {
    String exec() { 'B' }               (2)
}
class C implements A,B {}               (3)

def c = new C()
assert c.exec() == 'B'

class C implements A,B {
    String exec() { A.super.exec() }    (1)
}
def c = new C()
assert c.exec() == 'A'                  (2)

trait Extra {
    String extra() { "I'm an extra method" }            (1)
}
class Something {                                       (2)
    String doSomething() { 'Something' }                (3)
}

def s = new Something()
s.extra()

def s = new Something() as Extra                        (1)
s.extra()                                               (2)
s.doSomething()                                         (3)

trait A { void methodFromA() {} }
trait B { void methodFromB() {} }

class C {}

def c = new C()
c.methodFromA()                     (1)
c.methodFromB()                     (2)
def d = c.withTraits A, B           (3)
d.methodFromA()                     (4)
d.methodFromB()                     (5)

trait Filtering {                                       (1)
    StringBuilder append(String str) {                  (2)
        def subst = str.replace('o','')                 (3)
        super.append(subst)                             (4)
    }
    String toString() { super.toString() }              (5)
}
def sb = new StringBuilder().withTraits Filtering       (6)
sb.append('Groovy')
assert sb.toString() == 'Grvy'                          (7)

trait Greeter {
    String greet() { "Hello $name" }        (1)
    abstract String getName()               (2)
}

Greeter greeter = { 'Alice' }               (1)

void greet(Greeter g) { println g.greet() } (1)
greet { 'Alice' }                           (2)

import groovy.test.GroovyTestCase
import groovy.transform.CompileStatic
import org.codehaus.groovy.control.CompilerConfiguration
import org.codehaus.groovy.control.customizers.ASTTransformationCustomizer
import org.codehaus.groovy.control.customizers.ImportCustomizer

class SomeTest extends GroovyTestCase {
    def config
    def shell

    void setup() {
        config = new CompilerConfiguration()
        shell = new GroovyShell(config)
    }
    void testSomething() {
        assert shell.evaluate('1+1') == 2
    }
    void otherTest() { /* ... */ }
}

class AnotherTest extends SomeTest {
    void setup() {
        config = new CompilerConfiguration()
        config.addCompilationCustomizers( ... )
        shell = new GroovyShell(config)
    }
}

class YetAnotherTest extends SomeTest {
    void setup() {
        config = new CompilerConfiguration()
        config.addCompilationCustomizers( ... )
        shell = new GroovyShell(config)
    }
}

trait MyTestSupport {
    void setup() {
        config = new CompilerConfiguration()
        config.addCompilationCustomizers( new ASTTransformationCustomizer(CompileStatic) )
        shell = new GroovyShell(config)
    }
}

class AnotherTest extends SomeTest implements MyTestSupport {}
class YetAnotherTest extends SomeTest2 implements MyTestSupport {}
...

class Person {
    String name                                         (1)
}
trait Bob {
    String getName() { 'Bob' }                          (2)
}

def p = new Person(name: 'Alice')
assert p.name == 'Alice'                                (3)
def p2 = p as Bob                                       (4)
assert p2.name == 'Bob'                                 (5)

class CommunicationService {
    static void sendMessage(String from, String to, String message) {       (1)
        println "$from sent [$message] to $to"
    }
}

class Device { String id }                                                  (2)

trait Communicating {
    void sendMessage(Device to, String message) {
        CommunicationService.sendMessage(id, to.id, message)                (3)
    }
}

class MyDevice extends Device implements Communicating {}                   (4)

def bob = new MyDevice(id:'Bob')
def alice = new MyDevice(id:'Alice')
bob.sendMessage(alice,'secret')                                             (5)

class SecurityService {
    static void check(Device d) { if (d.id==null) throw new SecurityException() }
}

@SelfType(Device)
@CompileStatic
trait Communicating {
    void sendMessage(Device to, String message) {
        SecurityService.check(this)
        CommunicationService.sendMessage(id, to.id, message)
    }
}

class MyDevice implements Communicating {} // forgot to extend Device

class 'MyDevice' implements trait 'Communicating' but does not extend self type class 'Device'

interface HasHeight { double getHeight() }
interface HasArea { double getArea() }

@SelfType([HasHeight, HasArea])                       (1)
@Sealed(permittedSubclasses=[UnitCylinder,UnitCube])  (2)
trait HasVolume {
    double getVolume() { height * area }
}

final class UnitCube implements HasVolume, HasHeight, HasArea {
    // for the purposes of this example: h=1, w=1, l=1
    double height = 1d
    double area = 1d
}

final class UnitCylinder implements HasVolume, HasHeight, HasArea {
    // for the purposes of this example: h=1, diameter=1
    // radius=diameter/2, area=PI * r^2
    double height = 1d
    double area = Math.PI * 0.5d**2
}

assert new UnitCube().volume == 1d
assert new UnitCylinder().volume == 0.7853981633974483d

final class Foo implements FooTrait {}

@SelfType(Foo)
trait FooTrait {}

@Sealed(permittedSubclasses='Foo') (1)
trait FooTrait {}

trait Counting {
    int x
    void inc() {
        x++                             (1)
    }
    void dec() {
        --x                             (2)
    }
}
class Counter implements Counting {}
def c = new Counter()
c.inc()

public record Warning(String message) {
    public Warning {
        Objects.requireNonNull(message)
        message = message.toUpperCase()
    }
}

def w = new Warning('Help')
assert w.message() == 'HELP'

record ColoredPoint(int x, int y = 0, String color = 'white') {}

assert new ColoredPoint(5, 5, 'black').toString() == 'ColoredPoint[x=5, y=5, color=black]'
assert new ColoredPoint(5, 5).toString() == 'ColoredPoint[x=5, y=5, color=white]'
assert new ColoredPoint(5).toString() == 'ColoredPoint[x=5, y=0, color=white]'

ColoredPoint(int, int, String)
ColoredPoint(int, int)
ColoredPoint(int)

assert new ColoredPoint(x: 5).toString() == 'ColoredPoint[x=5, y=0, color=white]'
assert new ColoredPoint(x: 0, y: 5).toString() == 'ColoredPoint[x=0, y=5, color=white]'

@TupleConstructor(defaultsMode=DefaultsMode.OFF)
record ColoredPoint2(int x, int y, String color) {}
assert new ColoredPoint2(4, 5, 'red').toString() == 'ColoredPoint2[x=4, y=5, color=red]'

@TupleConstructor(defaultsMode=DefaultsMode.ON)
record ColoredPoint3(int x, int y = 0, String color = 'white') {}
assert new ColoredPoint3(y: 5).toString() == 'ColoredPoint3[x=0, y=5, color=white]'

package threed

import groovy.transform.ToString

@ToString(ignoreNulls=true, cache=true, includeNames=true,
          leftDelimiter='[', rightDelimiter=']', nameValueSeparator='=')
record Point(Integer x, Integer y, Integer z=null) { }

assert new Point(10, 20).toString() == 'threed.Point[x=10, y=20]'

package twod

import groovy.transform.ToString

@ToString(ignoreNulls=true, cache=true, includeNames=true,
          leftDelimiter='[', rightDelimiter=']', nameValueSeparator='=')
record Point(Integer x, Integer y) { }

assert new Point(10, 20).toString() == 'twod.Point[x=10, y=20]'

record Point(int x, int y, String color) { }

def p = new Point(100, 200, 'green')
def (x, y, c) = p.toList()
assert x == 100
assert y == 200
assert c == 'green'

record Point(int x, int y, String color) { }

def p = new Point(100, 200, 'green')
assert p.toMap() == [x: 100, y: 200, color: 'green']

record Point(int x, int y, String color) { }

def p = new Point(100, 200, 'green')
assert p.size() == 3

record Point(int x, int y, String color) { }

def p = new Point(100, 200, 'green')
assert p[1] == 200

@RecordOptions(copyWith=true)
record Fruit(String name, double price) {}
def apple = new Fruit('Apple', 11.6)
assert 'Apple' == apple.name()
assert 11.6 == apple.price()

def orange = apple.copyWith(name: 'Orange')
assert orange.toString() == 'Fruit[name=Orange, price=11.6]'

@ImmutableProperties
record Shopping(List items) {}

def items = ['bread', 'milk']
def shop = new Shopping(items)
items << 'chocolate'
assert shop.items() == ['bread', 'milk']

import groovy.transform.*

@RecordOptions(components=true)
record Point(int x, int y, String color) { }

@CompileStatic
def method() {
    def p1 = new Point(100, 200, 'green')
    def (int x1, int y1, String c1) = p1.components()
    assert x1 == 100
    assert y1 == 200
    assert c1 == 'green'

    def p2 = new Point(10, 20, 'blue')
    def (x2, y2, c2) = p2.components()
    assert x2 * 10 == 100
    assert y2 ** 2 == 400
    assert c2.toUpperCase() == 'BLUE'

    def p3 = new Point(1, 2, 'red')
    assert p3.components() instanceof Tuple3
}

method()