Grails 第二课

package helloworld
import groovy.swing.SwingBuilder
import java.awt.BorderLayout
import groovy.swing.SwingBuilder
import java.awt.BorderLayout as BL
import org.junit.*;
import java.util.*;

class HelloController {


    enum Day{SUNDAY,MONDAY, TUESDAY, WEDNESDAY,THURSDAY, FRIDAY, SATURDAY}

    enum Planet {MERCURY(3.303e+23, 2.4397e6),
                 VENUS(4.869e+24, 6.0518e6),
                 EARTH(5.976e+24, 6.37814e6),
                 MARS(6.421e+23, 3.3972e6),
                 JUPITER(1.9e+27,7.1492e7),
                 SATURN(5.688e+26, 6.0268e7),
                 URANUS(8.686e+25, 2.5559e7),
                 NEPTUNE(1.024e+26, 2.4746e7)
                 double mass;
                 double radius;
                 Planet(double mass, double radius){
                    this.mass = mass;
                    this.radius = radius;
                 }
                 void printMe(){
                     println "has a mass of and a radius of<BR>";
                     println "mass:"+mass+", radius:"+radius;
                     //render "printMe:<BR>";
                     //println "AAAA";

                 }
               }

    def index() { 
    	    //def grailsVersion = grailsApplication.metadata['app.grails.version'];
          //render "Hello World!"+grailsVersion;
          //render grailsVersion;
          //def mySet = false;
          //def mySet = Boolean.FALSE;
          //if(mySet){
               //render "true";
          //}else{
          	   //render "false";
          //}
          //String str = null;
          //assert str_ = = null;
          //render "Hello world it is"+new java.util.Date() + grailsVersion;
          //String str = null;
          //assert str1 == null;

          
          //Groovy基本语法
          //int i = 123 + 45 *67;
          //render i+"<BR>";
          //def x = new java.util.Date();
          //render x; //不能直接跟字符串,可能是数据类型问题
          //render "<BR>";
          //Boolean y = false;
          //render y+"<BR>";


          //List和Maps
          //List myList = [1776, -1, 33, 99, 0, 928734928763];


          //Groovy语法简介

          //1 没有类型的java
              //仅仅要求变量名前使用关键字def(groovy jsr 1开始,在以前的版本中,甚至连def都不需要)
              def var = "hello world";
              render var+"<BR>";
              render var.class; //查看变量的类型
              //对象输出后面不能跟+号字符链接符号
              //作为例外,方法参数和循环变量的声明不需要def
          //2 不需要的public
          //3 不需要的语句结束符
          //4 字符串链接符
               def var2 = "hello world groovy!";
               render "<BR>"+var2+"<BR>";    
          //5 一切皆有对象
              def var3 = "hello "+
                         "world"+
                         ", groovy!";
              render var3+"<BR>";
              render var3.class;
              render "<BR>";
              var3 = 1001;
              render "<BR>重新赋值后的类型:";
              render var3.class;     
          //6 循环
              //def var4 = "hello "+ "world "+", groovy!";
              //def repeat(val){
                  //for(i=0; i<5; i++){
                    //render val+"<BR>";
                  //}
              //}          
              //repeat(var4);
              //这样直接循环错误哦

          //7 String和Gstring
              def i=22;
              def val4="xlc";
              //render "this is ${$val4}:${i}";  不支持了
              render "<BR>this is "+val4+":"+i+"<BR>";  

          //8 范围
              def j=22;
              for (jj in 0..<5){
                 render jj;
              }
              //render "<BR><BR>";
              //不成功
              //for(jjj in a..<e){
                  //render jjj;
              //}
          //9 默认参数值
              /*def repet(val, repeat=3){
                  for(i in 0..<repeat){
                     render "this is ....";
                  }
              }*/
              //这个例子肯定运行不了
          //10 集合
              //Groovy支持最常见的两个java集合,java.util.Collection和java.util.Map
              //前面所说的范围实际也是集合的一种java.util.List
              //(1)Collection
                   //添加
                   def collect = ["a","b","c"];  
                   collect.add(1);
                   collect<<"come on";
                   collect[collect.size()]=100.0;
                   //输出
                   render collect[0]+"<BR>";
                   render collect[collect.size()-1]+"<BR>";
                   render collect.size();
                   for(i=0; i<collect.size(); i++){
                      render i+":"+collect[i]+"<BR>";
                   }
                   //groovy支持负索引
                   render "-1:"+collect[-1]+"<BR>"; //索引其倒数第1个元素
                   render "-2:"+collect[-2]+"<BR>"; //索引其倒数第2个元素

                   //collection支持集合运算
                   collect = collect + 5;
                   render collect[collect.size()-1]+"<BR>";
                   collect = collect-'a';
                   render collect[0];

                   //同样的,你可以往集合中添加另一个集合或删除一个集合
                   collect = collect-collect[0..4]; //把集合的前5个元素去掉
                   render collect[0]+"<BR>"; //现在集合中仅有一个元素,即原来的最后一个元素
                   render collect[-1]+"<BR>"; //也可以用负索引,证明最后一个元素就是第一个元素
                //Map
                    def map = ["name":"john", "age":14, "sex":"boy"];
                    map = map+["weight":25];
                    map = map+["length":1.27];
                    map.father = "Keller";
                    render map['father']+"<BR>";
                    render map.length+"<BR>"; 
            //11 闭包(Closure)
                //key, value两个参数用于接受每个元素的键/值
                map.each({key,value->render "$key:$value <BR>"});
                map.each{render it}  //it是一个关键字,代表map集合的每个元素
                render "<BR>";
                map.each({render it.getKey()+"--->"+it.getValue()});
                //除了用于迭代之外,闭包也可以单独定义
                def say = {
                   word->render "Hi, $word!<BR>";
                }
                //调用 
                say('groovy');
                say.call("groovy&grails");
          //12 类
             //(1) 不需要public修饰符
             //(2) 不需要类型说明
             //(3) 不需要getter/setter方法
             //(4) 不需要构造函数
             //(5) 不需要return
             //(6) 不需要()号
                //Groovy中方法调查用可以省略()号(构造函数除外),也就是说下面两句是等同的
                //person1.setName 'kk';
                //preson1.setName ('kk');
             //标准java写法
             def person1 = new Person();
             person1.name = 'kk';
             person1.age = 20;
             render person1;   
             render "<BR>";

             def person2 = new Person(["name":'gg', "age":33]);
             render person2;
             render "<BR>";
             //这样需要要注意我们覆盖了Object的toString方法,因为我们想通过render person1这样的方法简单地打印对象的属性值
             //然而toString方法中并没有return一个string,但不用担心,Groovy默认返回方法的最后一行的值
        //13 ?运算符
             //rs ?.next();
             //?在这里是一个条件运算符,如果?前面的对象非null,执行后面的方法,否则什么也不做
        //14 可变参数
             //等同于java5中的变长参数,首先我们定义一个变长参数的方法sum:
             //下面的测试没有通过
             /*int sum(int... var)
             {
                 def total = 0;
                 for(i in var){
                    total += i;
                 }
                 return total;
             }      
             render sum(1); */
        //15 枚举
           //  enum Day{ SUNDAY, MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY}
           //enum Planet {MERCURY(3.303e+23, 2.4397e6)}
           //enum Day{SUNDAY,MONDAY, TUESDAY, WEDNESDAY,THURSDAY, FRIDAY, SATURDAY}
           //这个枚举要定义到函数的外面,也就是类的下面
           //然后我们在swith语句中使用他
           def today = Day.SATURDAY;
           render today;
           switch(today){
               case "SATURDAY":
               render "可以休息啦<BR>";
               break;
               case Day.MONDAY..Day.FRIDAY:
               render "今天得上班啊<BR>";
               break;
               default:
               render "这么奇怪<BR>";
           }
           //同java5一样,groovy支持带构造器,属性和方法的enum:
           //如顶部构造函数
           Planet.EARTH.printMe();
           //println是只能在命令窗口出现的打印数据
      //16 Elvis操作符
           //这是三目运算符"?:"的简单形式,三目运算符通常以这种形式出现
           def name = null;
           //String displayName = name !=null ? name : "Unknown";
           //String displayName = name ? name : "Unknown";
           String displayName = name ?: "Unknown";
           render displayName+"<BR>";

      //17 动态性
           //Groovy所有对象都有一个元类metaClass,我们可以通过metaClass属性访问该元类,通过元类,可以为这个对象增加方法
           //下面代码,msg是一个String,通过元类,我们为msg增加了一个String类中所没有方法up:
           def msg = "Hello";
           render msg.metaClass
           render "<BR>";
           //添加元件到没有成功
           //String.metaClass.up = { delegate.toUpperCase();}
           //render msg.up();

           //通过元类,我们还可以检索对象所拥有的方法和属性(就像反射)
           msg.metaClass.methods.each{ render it.name+"<BR>"; }
           msg.metaClass.properties.each{ render it.name+"<BR>";}

           //我们可以通过元类判断有没有一个叫up的主应运而生,然后再调用它
           if(msg.metaClass.respondsTo(msg, 'up')){
               render  "ok exists<BR>";
           }else{
               render  "isexists up<BR>";
           }
           if(msg.metaClass.hasProperty(msg, 'bytes')){
              render msg.bytes.encodeBase64();
           }
      //18 Groovy swing
      //好像是生成表单和按钮,但没成功
      /*def swing = new SwingBuilder()
      count = 0
      def textlabel
      def frame = swing.frame(title:'Frame', size:[300,300]) {
      borderLayout()
      textlabel = label(text:"Clicked ${count} time(s).",
      constraints: BL.NORTH)
      button(text:'Click Me',
      actionPerformed: {count++; textlabel.text =
      "Clicked ${count} time(s)."; println "clicked"},
      constraints:BorderLayout.SOUTH)
      }
      frame.pack()
      frame.show()def swing = new SwingBuilder()
      count = 0
      def textlabel
      def frame = swing.frame(title:'Frame', size:[300,300]) {
      borderLayout()
      textlabel = label(text:"Clicked ${count} time(s).",
      constraints: BL.NORTH)
      button(text:'Click Me',
      actionPerformed: {count++; textlabel.text =
      "Clicked ${count} time(s)."; println "clicked"},
      constraints:BorderLayout.SOUTH)
      }
      frame.pack()
      frame.show()*/
            


                






    }
}

class Person
{
    def name;
    def age;
    //注意方法的类型String,因为我们要覆盖的方法为String类型
    String toString(){
       "$name,$age";
    }
}

  

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