append - How to read a file in Groovy into a string?

contains if (6)

I need to read a file from the file system and load the entire contents into a string in a groovy controller, what's the easiest way to do that?


A slight variation...

new File('/path/to/file').eachLine { line ->
  println line

In my case new File() doesn't work, it causes a FileNotFoundException when run in a Jenkins pipeline job. The following code solved this, and is even easier in my opinion:

def fileContents = readFile "path/to/file"

I still don't understand this difference completely, but maybe it'll help anyone else with the same trouble. Possibly the exception was caused because new File() creates a file on the system which executes the groovy code, which was a different system than the one that contains the file I wanted to read.

String fileContents = new File('/path/to/file').text

If you need to specify the character encoding, use the following instead:

String fileContents = new File('/path/to/file').getText('UTF-8')

The shortest way is indeed just

String fileContents = new File('/path/to/file').text

but in this case you have no control on how the bytes in the file are interpreted as characters. AFAIK groovy tries to guess the encoding here by looking at the file content.

If you want a specific character encoding you can specify a charset name with

String fileContents = new File('/path/to/file').getText('UTF-8')

See API docs on File.getText(String) for further reference.

Here you can Find some other way to do the same.

Read file.

File file1 = new File("C:\Build\myfolder\myTestfile.txt");
def String yourData = file1.readLines();

Read Full file.

File file1 = new File("C:\Build\myfolder\myfile.txt");
def String yourData= file1.getText();

Read file Line Bye Line.

File file1 = new File("C:\Build\myfolder\myTestfile.txt");
for (def i=0;i<=30;i++) // specify how many line need to read eg.. 30
{ file1.readLines().get(i)


Create a new file.

new File("C:\Temp\FileName.txt").createNewFile();

I have created a function that will allow you to use similar verbiage to C#/Java to include a JavaScript file. I've tested it a little bit even from inside of another JavaScript file and it seems to work. It does require jQuery though for a bit of "magic" at the end.

I put this code in a file at the root of my script directory (I named it global.js, but you can use whatever you want. Unless I'm mistaken this and jQuery should be the only required scripts on a given page. Keep in mind this is largely untested beyond some basic usage, so there may or may not be any issues with the way I've done it; use at your own risk yadda yadda I am not responsible if you screw anything up yadda yadda:

* @fileoverview This file stores global functions that are required by other libraries.

if (typeof(jQuery) === 'undefined') {
    throw 'jQuery is required.';

/** Defines the base script directory that all .js files are assumed to be organized under. */
var BASE_DIR = 'js/';

* Loads the specified file, outputting it to the <head> HTMLElement.
* This method mimics the use of using in C# or import in Java, allowing
* JavaScript files to "load" other JavaScript files that they depend on
* using a familiar syntax.
* This method assumes all scripts are under a directory at the root and will
* append the .js file extension automatically.
* @param {string} file A file path to load using C#/Java "dot" syntax.
* Example Usage:
* imports('core.utils.extensions');
* This will output: <script type="text/javascript" src="/js/core/utils/extensions.js"></script>
function imports(file) {
    var fileName = file.substr(file.lastIndexOf('.') + 1, file.length);

    // Convert PascalCase name to underscore_separated_name
    var regex = new RegExp(/([A-Z])/g);
    if (regex.test(fileName)) {
        var separated = fileName.replace(regex, ",$1").replace(',', '');
        fileName = separated.replace(/[,]/g, '_');

    // Remove the original JavaScript file name to replace with underscore version
    file = file.substr(0, file.lastIndexOf('.'));

    // Convert the dot syntax to directory syntax to actually load the file
    if (file.indexOf('.') > 0) {
        file = file.replace(/[.]/g, '/');

    var src = BASE_DIR + file + '/' + fileName.toLowerCase() + '.js';
    var script = document.createElement('script');
    script.type = 'text/javascript';
    script.src = src;


file groovy