Groovy学习笔记

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x = new Date();

x = 1;??????? //动态类型

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double y = -3.1415926;

y = new Date();??????? //静态类型，出现错误

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jvmLanguages = ["java","Groovy","Scala","Clojure"];

println(jvmLanguages[0]);

println(jvmLanguages.size());

println(jvmLanguages[0..2]);

println(jvmLanguages[-1]);

jvmLanguages = [];

println(jvmLanguages);

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languagesRatings = [Java:100, Groovy:99, Clojure:"N/A"];

println(languagesRatings["java"]);

println(languagesRatings.Clojure);

languagesRatings["Clojure"] = 75;

languagesRatings = [:];

println languagesRatings;

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public class Test{

????public Integer doStuff(){

????????def x = 1?????????? //没有分号

????????def y; def String z = "Hello";

????????x = 3?????????????? //默认返回

????}

}

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println("It‘s Groovy baby, year!") //等同于

println "It‘s Groovy baby, year!"

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class Test{?????????????????????? //默认为public

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????Integer x = new Integer(2)

????Integer y = new Integer(2)

????Integer z = null

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????Integer doStuff(){??????????? //默认为public

????????if (x == y){????????????? //隐含equals()调用

????????????println "x==y"

????????}

????????if (!x.is(y)){??????????? //检查对象是否相等

????????????println "x is not y"

????????}

????????if (z.is(null)){????????? //检查是否为null

????????????println "z is null"

????????}

????????if (z == null){?????????? //检查是否为null

????????????println "z is null"

????????}

????}

}

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class Character{

????private int strength

????private int wisdom

}

def pc = new Character(strength:10, wisdom:15)?? //bean初始化

pc.strength = 15???????????????????????????????? //set方法

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people = [null, new Person(name:"liyongjie")]

for (Person person : people){

????println people?.name

}

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// Java

String agentStatus = "Active";

String status = agentStatus != null ? agentStatus : "Inactive";

// Groovy

String status = agentStatus ? agentStatus : "Inactive"

// or

String status = agentStatus ? "Inactive"

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//GString，不能用于映射中的键或者比较是否相等

String name = "liyongjie"

def dist = 3 * 2

String crawling = "${name} is crawling ${dist} feet!"

//跨行字符串

"""This GString

wraps over two lines"""

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def sayHello = {

????name ->

????if (name == "Martijn" || name == "Ben")

????????"Hello author" + name + "!"

????else

????????"Hello reader" + name + "!"

}

println(sayHello("Martijn"))

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方法

描述

each

遍历集合，对其中的每一项应用函数字面值

collect

收集在集合中每一项上应用函数字面值的返回结果（相当于其他语言map/reduce中的map函数）

inject

用函数字面值处理集合并构建返回值（相当于其他语言里map/reduce中的reduce函数）

findAll

找到集合中所有与函数字面值匹配的元素

max

返回集合中的最大值

min

返回集合中的最小值

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movieTitles = ["seven","show","hard"]

movieTitles.each({x -> println x})

// 使用隐含的it变量

movieTitles.each({println it})

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方法

描述及Java中的对等物

~

创建一个模式（创建一个编译的Java Pattern对象）

=~

创建一个匹配器（创建一个Java Matcher对象）

==~

计算字符串（相当于在Pattern上调用match()方法）

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Pattern pattern = Pattern.compile("1010");

String input = "1010";

Matcher matcher = pattern.matcher(input);

if (input.matches("1010")){

????input = matcher.replaceFirst("0101");

????System.out.println(input);

}

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def pattern = /1010/

def input = "1010"

def matcher = input =~ pattern

if (input ==~ pattern){

????input = matcher.replaceFirst("0101")

????println input

}

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( "Hazel 1" =~ /(\w+)(\d+)/ ).each {full, name, age

????????????????????????????????????-> println "${name} is ${age} years old."}

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def writer = new StringWriter()

def xml = new groovy.xml.MarkupBuilder(writer)

xml.person(id:2) {

????name "Gweneth"

????age 1

}

println.writer.toString()

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<person id=‘2‘>

????<name>Gweneth</name>

????<age>1</age>

</person>

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方法

描述

XMLParser

支持XML文档的GPath表达式

XMLSlurper

跟XMLParser类似，但以懒加载的方式工作

DOMCategory

用一些语法支持DOM的底层解析

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class XmlExample {

????static def PERSON =

????"""

????<person id=‘2‘>

????????<name>Gweneth</name>

????????<age>1</age>

????</person>

????"""

}

class Person {def id; def name; def age}

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def xmlPerson = new XMLParser().

????????????????????parseText(XmlExample.PERSON)

Person p = new Person(id:xmlPerson.@id,

????????????????????name:xmlPerson.name.text(),

????????????????????age:xmlPerson.age.text())

println "${p.id}, ${p.name}, ${p.age}"

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Binding binding = new Binding();

binding.setVariable("x", 2.4);

binding.setVariable("y", 8);

GroovyShell shell = new GroovyShell(binding);?? //设置shell上的binding

Object value = shell.evaluate("x + y");???????? //计算并返回表达式

assert value.equals(new BigDecimal(10.4));

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GroovyClassLoader loader = new GroovyClassLoader();?? //准备类加载器

Class<?> groovyClass = loader.parseClass(

????????????????new File("CalculateMax.groovy"));???? //从类文件得到Class对象

GroovyObject groovyObject = (GroovyObject)

????????????????groovyClass.newInstance();??????????? //生成实例对象

ArrayList<Integer> numbers = new ArrayList();

numbers.add(new Integer(1));????? //准备参数

numbers.add(new Integer(10));

Object[] arguments = {numbers};

Object value = GroovyObject

????????.invokeMethod("getMax", arguments);???? //调用groovy方法

assert value.equals(new Integer(10))

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String[] roots = new String[] {"/src/main/groovy"}; //设置根目录

GroovyScriptEngine gse =

????????????????new GroovyScriptEngine(roots); //初始化引擎

Binding binding = new Binding();

binding.setVariable("name","liyongjie");

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Object output = gse.run("Hello.groovy", binding); //运行脚本

assert output.equals("Hello liyongjie");