The Format of Properties Files

In this section, we will discuss the format of a properties file, such as i3-label.properties.

A properties file is a simple text file. The file contains a list of key=value pairs, such as

# This is the default LabelsBundle.properties file
s1=computer
s2=disk
s3=monitor
s4=keyboard

The default encoding of a properties file is assumed to be UTF-8. If you want to use a different encoding, please refer to the Use Encoding Other Than UTF-8 section.

A properties file is usually used to contain the internationalization labels of an application, but technically you could use it in any situation you'd like.

---

Specify a Value with Multiple Lines

By default, a property is the text specified right after the equal sign. If the property's value has multiple lines, you could use the following format:

key={
line 1
line 2
}

Notice that the curly braces must be followed by a line break immediately, and the right brace (}) must be the only character in the line.

Specify Segmented Keys

Since all internationalization labels are stored in the same scope, it is common to separate them by naming the key with dot (.) like the Java package name. For sake of description, we call them segmented key. For example,

order.fruit.name = Orange
order.fruit.description = A common fruit

It can be simplified by use of the following syntax:

order.fruit.  {
name = Orange
description = A common fruit
}

As shown, the segmented key could be specified by specifying the prefix and a following right brace ({).

The segmented key could be accessed in two ways.

First, with an implicit object called labels:

<textbox value="${labels.order.fruit.name}"/>

---

Under the hood: The labels object is actually the map returned by Labels.getSegmentedLabels(). Furthermore, if the key of a property contains dot (.), i.e., segmented, all properties with the same prefix are grouped as another map. For example, ${labels.order} (i.e., Labels.getSegmentedLables().get("order")) will return a map containing an entry (fruit) in the above example.

Second, with an EL function called [[ZUML Reference/EL Expressions/Core Methods/l|l] and/or l2:

<?taglib uri="http://www.zkoss.org/dsp/web/core" prefix="c"?>
<label value="${c:l('order.fruit.name')}">

Specify a Comment

You could put a comment line by starting with the sharp sign (#), such as

#This is a comment line that will be ignored when loaded

Use EL Expressions

EL expressions are allowed for a property's value. For example, you could reference a property's value in another property, such as

first=the first label
second=come after ${first}

Segmented keys are also allowed:

group1.first=the first group
group2.second=come after ${group1.first}

In addition to referencing another property, you could reference any implicit object specified in ZUML Reference: Implicit Objects if it is part of a HTTP request (excluding component/page).

For example, param references to a request's parameter:

message=Thank ${param.user} for using

Use Encoding Other Than UTF-8

By default, the encoding of properties files are assumed to be UTF-8. If you prefer another encoding, please specify it in a library property called org.zkoss.util.label.web.charset. It also means all properties files must be encoded in the same character set.

For more information, please refer to ZK Configuration Reference.

Version History

Version	Date	Content
5.0.7	Mar 2011	labels implicit object was introduced to access properties without declaring taglib. Also allows label keys of a.b.c format.