Groovy就是java世界的动态语言
一：快速开始（gettingStart）
安装JDK环境
Groovy需要JDK1.4以上版本的支持。因此在安装groovy时首先要安装JDK。
JDK安装步骤：
• 下载自己喜欢的JDK版本。（下载网址：http://java.sun.com）
• 下载Groovy：
Groovy的 下载首页截图
点击Download
进入下载页面
Groovy最新版本：Groovy 1.6-RC-2
我下载的是：Download Windows-Installer: Binary Release 安装版本
运行安装者
设置JAVA_HOME 环境变量. 在Windows平台里，步骤如下:
(1)打开系统"控制面板"
单击"高级"选项卡
单击"环境变量" 按钮
添加一个名称为"JAVA_HOME" 的新的系统环境变量，并且将你的Java的安装目录作为它的值 (例如，我的是C:"Program Files"Java"jdk1.6.0（版本号）)
你也可以添加 %JAVA_HOME%"bin到你的系统的PATH变量中
(2)右击我的电脑属性
点击高级选项
点击环境变量
点击新建选项：
具体设置
Path：
我用的Jdk版本是Jdk1.6
• 运行安装文件。（更改安装路径到：C:"Program Files"Java"jdk1.6.0（版本号））
• 设置JAVA_HOME环境变量（如我的
• 在系统path中增加：%JAVA_HOME%"bin
注：对于1.1-rc-1以上版本需要JDK1.5版或更高的版本。
点击自己下载的Groovy windows安装版本
安装可以是默认的安装全点击下一步（next）：
安装就完成啦
(Note: as an alternative to setting a system environment variable, you can create yourself a '.bat' or '.cmd' file which sets
the variable. You then need to run that batch file in any console window in which you wish to run Java and double clicking on
.bat' or '.cmd' files containing Java invocation instructions won't work. If you are unsure about what this means, follow
the earlier instructions.)
Note: JDK 1.5 is required for version 1.1-rc-1. In earlier versions of JDK (notably 1.4.2) the compiller throws an exception:
*nested exception is org.codehaus.groovy.runtime.InvokerInvocationException: java.lang.NoSuchMethodError:
java.lang.String.replace(Ljava/lang/CharSequence;Ljava/lang/CharSequence;)Ljava/lang/String;
The method "replace" was introduced in JDK 1.5 and is not supportedin earlier versions. This is also a reason why GRails
framework doesn't run on JRE 1.4
(1)如果你是安装版本Groovy环境变量不需要我们设置，在安装的时候就自动设置好啦。
(2)如果不是，请自己尝试Groovy设置如下：
设置你的Groovy环境变量
从下载页面下载Groovy安装器或者二进制包，并且跟着介绍进行安装即可。（当前有一个问题，就是在windows下，你的安装路径不能含有空格
，即，要将其缺省的安装路径"c:"Program Files"Groovy" 改成象"c:"Groovy"这样的路径）
或者这样
从站点上得到Groovy发行版的copy,并且copy它到你硬盘上的某个地方。
解压缩这个groovy包到你硬盘的某个空间，如我的在 C:"dev"groovy-1.0-jsr-06
设置GROOVY_HOME环境变量. 在Windows下，作如下步骤:
添中新的系统环境变量GROOVY_HOME 并且将值设为你的groovy安装的路径（ 我的是 C:"dev"groovy-1.0-jsr-06)
打开命令行窗口，并且键入"set" 然后打回车，查看你的环境变量设置是否已经正确。
可选的，你也可以添加 %GROOVY_HOME%"bin 到你的PATH环境变量中
通过双击试着运行groovyConsole.bat。如果它不能工作，打开一人命令行窗口，将目录改变到bin目录，并且运行它看他返回什么错误信息。
二：运行groovy
Groovy安装：目录
我们需要点击groovyConsole.bat文件：
文件详细内容如下：
| @if "%DEBUG%" == "" @echo off @rem @rem $Revision: 2770 $ $Date: 2005-08-29 12:49:42 +0200 (Mo, 29. Aug 2005) $ @rem @rem Set local scope for the variables with windows NT shell if "%OS%"=="Windows_NT" setlocal :begin @rem Determine what directory it is in. set DIRNAME=%~dp0 if "%DIRNAME%" == "" set DIRNAME=." "%DIRNAME%"startGroovy.bat" "%DIRNAME%" groovy.ui.Console %* @rem End local scope for the variables with windows NT shell if "%OS%"=="Windows_NT" endlocal |
安装完整无误的话 运行groovyConsole.bat就会启动groovyConsole.exe，出来一个编辑框。
上面的是文本输入框：根据groovy的语法输入要显示的内容：
下面的是内容输出框：显示上面的内容：
开始运行groovy：
Hello, World
在 groovyConsole运行窗口的顶部,键入println "Hello, World!"
并且键入 <CTRL-R>.
注意，在控制台窗口中（即 groovyConsole窗口前面的黑色的那个），文体得到打印并且 groovyConsole的下部显示 :
groovy> println "Hello, World!"
null
以"groovy>"开头的行正是控制台处理的文本. "null" 是表达式的值. 因为表达式没有任何值可以打印 ，所以groovyConsole打印为"null"
接下来，再试一些实际的值，用下面的字符串来替换控制台里的文本：
123+45*67
或者你喜欢的任何表达式然后按<CTRL-R> (I'm going to stop telling you to hit <CTRL-R>, I think you get the idea). 现在， groovyConsole下面打印的值有更多的含义.
Variables
You can assign values to variables for later use. Try the following:x = 1
println x
x = new java.util.Date()
println x
x = -3.1499392
println x
x = false
println x
x = "Hi"
println x
Lists and Maps
The Groovy language has built-in support for two important data types, lists and maps (Lists can be operated as arrays in Java language). Lists are used to store ordered collections of data. For example an integer list of your favorite integers might look like this:myList = [1776, -1, 33, 99, 0, 928734928763]
You can access a given item in the list with square bracket notation (indexes start at 0):
println myList[0]
Should result in this output:
1776
You can get the length of the list with the "size" method:
println myList.size()
Should print out:
6
But generally you shouldn't need the length, because unlike Java, the preferred method to loop over all the elements in an list is to use the "each" method, which is described below in the "Code as Data" section.
Another native data structure is called a map. A map is used to store "associative arrays" or "dictionaries". That is unordered collections of heterogeneous, named data. For example, let's say we wanted to store names with IQ scores we might have:
scores = [ "Brett":100, "Pete":"Did not finish", "Andrew":86.87934 ]
Note that each of the values stored in the map is of a different type. Brett's is an integer, Pete's is a string, and Andrew's is a floating point number. We can access the values in a map in two main ways:
println scores["Pete"]
println scores.Pete
Should produce the output:
Did not finish
Did not finish
To add data to a map, the syntax is similar to adding values to an list. For example, if Pete re-took the IQ test and got a 3, we might:
scores["Pete"] = 3
Then later when we get the value back out, it will be 3.
println scores["Pete"]
should print out 3.
Also as an aside, you can create an empty map or an empty list with the following:
emptyMap = [:]
emptyList = []
To make sure the lists are empty, you can run the following lines:
println emptyMap.size()
println emptyList.size()
Should print a size of 0 for the List and the Map.
条件表达式
One of the most important features of any programming language is the ability to execute different code under different conditions. The simplest way to do this is to use the '''if''' construct. For example:amPM = Calendar.getInstance().get(Calendar.AM_PM)
if (amPM == Calendar.AM)
{
println("Good morning")
} else {
println("Good evening")
}
Don't worry too much about the first line, it's just some code to determine whether it is currently before noon or after. The rest of the code executes as follows: first it evaluates the expression in the parentheses, then depending on whether the result is '''true''' or '''false''' it executes the first or the second code block. See the section below on boolean expressions.
Note that the "else" block is not required, but the "then" block is:
amPM = Calendar.getInstance().get(Calendar.AM_PM)
if (amPM == Calendar.AM)
{
println("Have another cup of coffee.")
}
Boolean表达式
There is a special data type in most programming languages that is used to represent truth values, '''true''' and '''false'''. The simplest boolean expression are simply those words. Boolean values can be stored in variables, just like any other data type:myBooleanVariable = true
A more complex boolean expression uses one of the boolean operators:
==
!=
>
>=
<
<=
Most of those are probably pretty intuitive. The equality operator is '''==''' to distinguish from the assignment operator '''='''. The opposite of equality is the '''!=''' operator, that is "not equal"
So some examples:
titanicBoxOffice = 1234600000
titanicDirector = "James Cameron"
trueLiesBoxOffice = 219000000
trueLiesDirector = "James Cameron"
returnOfTheKingBoxOffice = 752200000
returnOfTheKingDirector = "Peter Jackson"
theTwoTowersBoxOffice = 581200000
theTwoTowersDirector = "PeterJackson"
titanicBoxOffice > returnOfTheKingBoxOffice // evaluates to true
titanicBoxOffice >= returnOfTheKingBoxOffice // evaluates to true
titanicBoxOffice >= titanicBoxOffice // evaulates to true
titanicBoxOffice > titanicBoxOffice // evaulates to false
titanicBoxOffice + trueLiesBoxOffice < returnOfTheKingBoxOffice + theTwoTowersBoxOffice // evaluates to false
titanicDirector > returnOfTheKingDirector // evaluates to false, because "J" is before "P"
titanicDirector < returnOfTheKingDirector // evaluates to true
titanicDirector >= "James Cameron" // evaluates to true
titanicDirector == "James Cameron" // evaluates to true
Boolean expressions are especially useful when used in conjunction with the '''if''' construct. For example:
if (titanicBoxOffice + trueLiesBoxOffice > returnOfTheKingBoxOffice + theTwoTowersBoxOffice)
{
println(titanicDirector + " is a better director than " + returnOfTheKingDirector)
}
An especially useful test is to test whether a variable or expression is null (has no value). For example let's say we want to see whether a given key is in a map:
suvMap = ["Acura MDX":""$36,700", "Ford Explorer":""$26,845"]
if (suvMap["Hummer H3"] != null)
{
println("A Hummer H3 will set you back "+suvMap["Hummer H3"]);
}
Generally null is used to indicate the lack of a value in some location.
Debugging and Troubleshooting Tips
Print out the class of a variable that you're interested in with myVar.getClass(). Then look up the documentation for that class.
If you're having trouble with a complex expression, pare it down to a simpler expression and evaluate that. Then build up to your more complex expression.
Try restarting the groovyConsole (this will clear out all the variables so you can start over.
Look for the topic you're interested in in the Groovy User Guide
If you are a Java developer
you might want to check on the Differences from Java
also there afew a few Things to remember
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