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Also pay your attention to the following Groovydoc references:

ff http://groovy.codehaus.org/groovy-jdk/java/io/File.html

ff http://groovy.codehaus.org/api/groovy/io/FileType.html

ff http://groovy.codehaus.org/api/groovy/io/FileVisitResult.html

Changing file attributes on Windows

Groovy is widely used as a scripting language for automating repetitive tasks. While working with files, it occurs sometime that one has to change the attributes of a file in Windows. For example, you may need to set the file as read-only, archived, and so on.

In this recipe, we will learn how to change file attributes in Windows using Groovy.

Getting ready

Let's start by creating a file and adding some content to it. Open your shell, start groovysh and type the following code:

f = new File('test.txt')

f << 'hello, this is a test file'

You should now see a file named test.txt in the same directory where you started groovysh.

On a DOS console, type:

attrib test.txt

The output should be as follows:

A

I

C:\hello.txt

The initial on the left stands for the first letter of the enabled attribute: A for "archive", S for "system", H for "hidden" and R for "read-only".

How to do it...

With the exclusion of the read-only attribute; in Java, there is no way to set the Windows file attributes through the File API. To make a file read-only:

f.setReadOnly()

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This will change the R attribute:

attrib test.txt

AR I C:\hello.txt

1.In order to change other file attributes, we have to resort to executing an external process with Groovy, using the execute method of String. The external process is the attrib DOS command that can be used to set and read file attributes.

2.To make a file "Hidden":

'attrib +H C:/hello.txt'.execute()

3.And to remove the "Hidden" attribute:

'attrib -H C:/hello.txt'.execute()

4.You can use the same approach for the other file attributes, S and A.

How it works...

Groovy provides a simple way to execute command line processes. Simply write the command line as a string and call the execute method. The execute method returns a java.lang. Process instance, which will subsequently allow the in/err/outstreams to be processed and the exit value from the process to be inspected.

This snippet executed from groovish will output the directory listing on a UNIX machine:

println 'ls -al'.execute().text

Alternatively, we can access the stream resulting from the process and print the result line-by-line:

p = 'ls -al'.execute().text p.in.eachLine { line -> print line }

There's more...

If you run Groovy using JDK 7, you can leverage the new NIO API to set the Windows file attributes. The following example shows you how to do it:

import java.nio.file.*

import java.nio.file.attribute.* def f = new File('hello.txt')

f << 'hello, hello'

def path = Paths.get('C:\\groovybook\\hello.txt') def dosView = Files.getFileAttributeView(

path, DosFileAttributeView

)

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dosView.hidden = true dosView.archive = true dosView.system = true

This code will fail if it is executed in an environment other than Windows.

Reading data from a ZIP file

Reading from a ZIP file with Groovy is a simple affair. This recipe shows you how to read the contents of a ZIP file without having to extract the content first.

Getting ready

Groovy doesn't have any GDK class to deal with ZIP files so we have to approach the problem by using one of the JDK alternatives. Nevertheless, we can "groovify" the code quite a lot in order to achieve simplicity and elegance.

How to do it...

Let's assume we have a ZIP file named archive.zip containing a bunch of text files.

1.The following code iterates through the ZIP entries and prints the name of the file as well as the content:

def dumpZipContent(File zipFIle) {

def zf = new java.util.zip.ZipFile(zipFIle) zf.entries().findAll { !it.directory }.each {

println it.name

println zf.getInputStream(it).text

}

}

dumpZipContent(new File('archive.zip'))

2.The output may look as follows:

a/b.txt

This is text file! c/d.txt

This is another text file!

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How it works...

The dumpZipContent function takes a File as an argument and creates a JDK ZipFIle out of it. Finally, the code iterates on all the entries of the ZIP file, filtering out the folders. The iteration is done through a couple of nested closures, the second of which prints the content of the ZIP file using the handy text property added to the Java's InputStream class by Groovy JDK.

There's more...

We have already encountered the AntBuilder class in the Deleting a file or directory recipe. This class is a gateway to the enormous amount of tasks exposed by the Ant build system.

Among them, we can find the unzip task that allows us to decompress a ZIP, JAR, WAR, and EAR file:

def ant = new AntBuilder()

ant.unzip (src: 'zipped.zip', dest: '.')

The previous snippet unzips a file named zipped.zip into the same folder where the code is executed. For a complete list of properties of the unzip task, refer to Ant documentation

(https://ant.apache.org/manual/Tasks/unzip.html).

See also

ff http://docs.oracle.com/javase/7/docs/api/java/util/zip/ZipFile. html

ff https://ant.apache.org/manual/Tasks/unzip.html

Reading an Excel file

In this recipe, you will learn how to read and extract data from an Excel file. If you are a

Windows or Mac user, changes are that you have worked in some capacity with Microsoft Excel, the de facto standard for spreadsheets. Excel files are often the default data interchange format of the enterprise. Entire departments are run using incredibly complex

Excel files with thousands of rows and absurdly convoluted formulas. As a programmer, it is often the case that you are asked to interact with such files.

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Getting ready

Groovy (and Java) does not offer any out-of-the-box ingredient to manipulate Excel files.

Fortunately, there is no shortage of third-party libraries that are able to deal with Microsoft documents. The undisputed king of this realm is Apache POI, the Java API for Microsoft documents. With Apache POI, it is possible to parse as well as write Excel 2007 OOXML documents (.xlsx) and older formats (.xls).

How to do it...

Let's start with a simple Excel file with only a few columns:

1.The script that follows, extracts the content of the Excel file depicted in the previous screenshot and prints it on the console:

@Grab('org.apache.poi:poi:3.8') @Grab('org.apache.poi:poi-ooxml:3.8') @GrabExclude('xml-apis:xml-apis')

import org.apache.poi.xssf.usermodel.XSSFWorkbook import org.apache.poi.xssf.usermodel.XSSFSheet def excelFile = new File('Workbook1.xlsx') excelFile.withInputStream { is ->

workbook = new XSSFWorkbook(is) (0..<workbook.numberOfSheets).each { sheetNumber ->

XSSFSheet sheet = workbook.getSheetAt( sheetNumber ) sheet.rowIterator().each { row ->

row.cellIterator().each { cell -> println cell.toString()

}

}

}

}

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