This plugin integrates the well established Barcode4j library to provide convenient generation of barcodes. The version of Barcode4j that is used is 2.0.

How it works

The plugin provides the barcode4jService. This service has methods for rendering a barcode image to an arbitrary output stream or to a http servlet response (convenience methods are also added to controllers to implicitly use the current response which is discussed later). These render methods take (among other options) a BarcodeGenerator in the form of either a literal instance, or as the name of a BarcodeGenerator bean defined in the application context (i.e. resources.groovy).

Generator Instances

For example, to generate a barcode to a PNG file using the Code39 scheme you would do…

import org.krysalis.barcode4j.impl.code39.Code39Bean
    
// Create and configure the generator
def generator = new Code39Bean()
generator.height = 10

def barcodeValue = "12345"
def imageMimeType = "image/png"

new File("barcode.png").withOutputStream { out ->
    barcode4jService.render(generator, barcodeValue, imageMimeType, out)
}

The barcode4jService has convenience methods of png, jpeg and gif that configure the appopriate mime type for you. For example…

new File("barcode.png").withOutputStream { out ->
    barcode4jService.png(generator, barcodeValue, out)
}

Generator Bean Names

It may be more convenient to manage the generator instance(s) via the application context. In resources.groovy we would have…

import org.krysalis.barcode4j.impl.code39.Code39Bean

beans = {
    code39Generator(Code39Bean) {
        height = 10
    }
}

We can now refer to this generator by name when rendering…

def barcodeValue = "12345"
def imageMimeType = "image/png"

new File("barcode.png").withOutputStream { out ->
    barcode4jService.render("code39Generator", barcodeValue, imageMimeType, out)
}

The same png, jpeg and gif convenience methods exist for this variant.

Rendering to the response

There are convenience methods added to all controller instances to render barcodes to the response. Our examples from above would become…

import org.krysalis.barcode4j.impl.code39.Code39Bean

class BarcodeController {
    def barcode = {
        // Create and configure the generator
        def generator = new Code39Bean()
        generator.height = 10

        def barcodeValue = "12345"

        renderBarcodePng(generator, barcodeValue)
    }
}

Or alternatively using the generator bean defined in the application context…

class BarcodeController {
    def barcode = {
        def barcodeValue = "12345"
        renderBarcodePng("code39Generator", barcodeValue)
    }
}

The convenience methods are named: renderBarcodePng, renderBarcodeJpeg and renderBarcodeGif.

Rendering Parameters

In addition to the individual configuration paramters for different barcode generators, there are 4 additional optional parameters that are configurable for a render. Each of these options has a corresponding default which is available as an instance variable of the barcode4jService, which allows you to override them globally at application startup (preferably via property override configuration).

// Config.groovy
beans {
    barcode4jService {
        defaultAntiAlias = true
    }
}

To override them for a particual render operation, you can supply a map of the parameters as the last argument to any variant of the rendering methods.

For example:

renderBarcodePng("code39Generator", barcodeValue, [antiAlias: true])

The parameters that are available…

dpi (type: int, default instance var name: defaultDpi, default value: 150)

Controls the dots per inch parameter of the rendering canvas.

imageType (type: int, default instance var name: defaultImageType, default value: java.awt.image.BufferedImage.TYPE_BYTE_BINARY)

Controls the “type” of image to be rendered. See the constants of the BufferedImage for more information.

antiAlias (type: boolean, default instance var name: defaultAntiAlias, default value: false)

Controls whether or not anti aliasing will be used for the rendering operation.

orientation (type: int, default instance var name: defaultOrientation, default value: 0)

The orientation of barcode in degrees, rotated from the natural orientation of the barcode (typically left to right horizontal). For example, setting a value of 180 would render the barcode upside down.

Why is there no controller or taglib?

The primary reason for this is to allow you as the developer to control access to the barcode generation in your application.

Help / Support

Please raise issues on the Grails user mailing list.

Licensing

ASL 2.0