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# Message Resource Files

This tutorial assumes you’ve completed the Form Validation tutorial and have a working form-validation project. The example code for this tutorial, message-resource, is available for checkout from the Struts GitHub repository at struts-examples.

## Introduction

In this tutorial we’ll explore using Struts message resource capabilities (also called resource bundles). Message resources provide a simple way to put text in a view page that is the same throughout your application, to create form field labels, and to change text to a specific language based on the user’s locale (i18n).

The Struts user mailing list is an excellent place to get help. If you are having a problem getting the tutorial example applications to work search the Struts mailing list. If you don’t find an answer to your problem, post a question on the mailing list.

## Message Resource Property Files

In a Struts web application you may associate a message resource property file with each Struts Action class by creating a properties file with the same name as the Action class and having the .properties extension. This properties file must go in the same package as the Action class. For our tutorial example, let’s say we want to place the form field labels into a separate file where we can easily change them and also provide the capability to display the labels in other languages.

If you’re doing this tutorial after completing Form Validation then you can make these changes to that tutorial’s example application.

Put the text below in a file named Register.properties in the `org.apache.struts.register.action` package in the `src/main/resources` folder.

Register.properties

    personBean.firstName=First name
    personBean.lastName=Last name
    personBean.age=Age
    personBean.email=Email
    thankyou=Thank you for registering %{personBean.firstName}.

The above is just a standard Java properties file. The key is to the left of the = sign and the value for the key is to the right. When the Register action is executed these properties will be available to the view page by referencing the key name.

## Struts Key Attribute

The Struts key attribute can be used in the textfield tag to instruct the framework what value to use for the textfield’s name and label attributes. Instead of providing those attributes and their values directly, you can just use the key attribute.

If you open register.jsp from the Form Validation tutorial you’ll see this Struts textfield tag:

textfield tag

    <s:textfield name="personBean.firstName" label="First name" />

Instead of specifying the name and label attributes you can just use the key attribute.

textfield tag with key attribute

    <s:textfield key="personBean.firstName"  />

The value for the key attribute instructs the Struts framework to use the same value for the name attribute (`personBean.firstName`). For the label attribute’s value the value of the key attribute is used by the Struts framework to find a key in a properties file with the same value. So in our example, Struts will look in `Register.properties` for a key with a value of `personBean.firstName`. The value of that key (`First name`) will be used as the label attribute’s value.

To enable the key attribute to find the properties file, the display of the view page must be the result of executing a Struts Action class. Right now if you examine index.jsp from the Form Validation tutorial the link to the `register.jsp` page is a standard URL.

link to register.jsp

    <p><a href="register.jsp">Please register</a> for our prize drawing.</p>

We need to change the above link so that it goes through the Register.java Struts Action class. Replace the above with this markup.

link to Register Action class

    <s:url action="registerInput" var="registerInputLink" />
    <p><s:a href="%{registerInputLink}">Please register</s:a> for our prize drawing.</p>

We use the Struts url tag to create a link to action registerInput. We then use that link as the value for the `href` attribute of the anchor tag. We must define the registerInput action in `struts.xml`. Add the following to `struts.xml`

registerInput action node for struts.xml

    <action name="registerInput" class="org.apache.struts.register.action.Register" method="input" >
        <result name="input">/register.jsp</result>
    </action>

The above action node instructs the Struts framework to execute class Register’s input method in response to action `registerInput`. The input method is inherited by class `Register` from class `ActionSupport`. The default behavior of the inherited input method is to return the String input. The result node above specifies that if the returned result is `input` then render the view `register.jsp`.

By doing the above the view page `register.jsp` will have access to the properties defined in `Register.properties`. The Struts framework will make those properties defined in `Register.properties` available to the view page since the view page was rendered after `Register.java` (the Struts Action class) was executed.

Follow the instructions (README.txt) in the project to create the war file and copy the war file to your servlet container. Open a web browser and navigate to the home page specified in the README.txt file (`index.action`). You should see a link to `registerInput.action` when mousing over the hyperlink `Please Register`.

When you click on the Please Register link your browser should display the `register.jsp`. The form field labels should be the key values from the `Register.properties` file.

## Struts Text Tag

We can also use the Struts text tag to display values from a properties file. In `thankyou.jsp` add this `text` tag instead of the `h3` tag that is in `thankyou.jsp`.

text tag

    <h3><s:text name="thankyou" /></h3>

Since `thankyou.jsp` is also rendered after executing the `Register.java` Action class, the key `thankyou` and its value will be available to the view page.

How did the value entered for the first name input field get displayed on `thankyou.jsp`? Look back at the value for the `thankyou` key in the `Register.properties` file.

Register.properties

    thankyou=Thank you for registering %{personBean.firstName}.

The markup `%{personBean.firstName}` tells Struts to replace this part with the result of calling `getPersonBean`, which returns a `Person` object. Then call the `getFirstName` method which returns a String (the value the user inputted into the `personBean.firstName` form field on `register.jsp`).

## Package Level Properties

What if you want a properties file with keys and values that can be referenced from multiple view pages and those view pages are rendered after executing different Action classes? Struts has the ability to use multiple property files provided the property file is found in the package hierarchy.

Place the following in a file named `package.properties` and save that file in package `org.apache.struts` in `src/main/resources`.

package.properties

    greeting=Welcome to The Wonderful World of Struts

Now any view rendered by an Action that is in the hierarchy `org.apache.struts...` can use a Struts `text` tag with a `name` attribute value of `greeting` to display the value of the `greeting` property key. For example add the following markup to `helloworld.jsp` before the `h2` tag.

Using properties set in package.properties

    <h1><s:text name="greeting" /></h1>

Then rebuild the war file and deploy it to your servlet container. Go to index.action and click on the link for Hello World. You should see:

The property keys and values defined in package.properties are available to any view that is rendered after executing an Action class that is the package hierarchy that includes `package.properties`.

## Global Properties

You can also specify a global property file in `struts.xml`. The keys and values defined in that property file will be available to all the view pages that are rendered after executing an Action class.

Add the following to a file named `global.properties` (note the name doesn’t have to be global).

global.properties

    contact=For assistance contact <a href='mailto:contact@email.com'>contact@email.com</a>

Save the `global.properties` file in the `src/main/resources` folder.

To inform the Struts framework about the `global.properties` file add the follow node to `struts.xml` after the constant `name="struts.devmode"` node.

Specify Global Property File In struts.xml

    <constant name="struts.custom.i18n.resources" value="global" />

To use the contact key in a view page, add the following markup to `index.jsp` just before the closing body tag.

Using contact property

    <hr />
    <s:text name="contact" />

Rebuild the war file, deploy it to your Servlet container, and then go to `index.action`. You should see:

Struts will look for a property key of contact in all the property files starting with the property file that matches the Action class, then in the property files that are in the package hierarchy of the Action class, and then in any property files specified in `struts.xml`. For this example Struts will find the contact key in `global.properties`. The value of the contact key will be displayed where we have put the text tag.

You can add the text tag above to all the JSPs in this example.

## Internationalization (i18n)

Using message resource files (resource bundles) also enables you to provide text in different languages. By default, Struts will use the user’s default locale. If that locale is en for English then the property files used will be the ones without a locale specification (for example `Register.properties`). If the locale is not English but say Spanish (es) then Struts will look for a properties file named `Register_es.properties`.

To provide an example of Struts support for i18n create a file named `Register_es.properties` and in that file add the following Spanish translations.

Register_es.properties

    personBean.firstName=Nombre
    personBean.lastName=Apellidos
    personBean.age=Edad
    personBean.email=Correo
    thankyou=Gracias por registrarse, %{personBean.firstName}.

> My apologies to Spanish language speakers for any mistakes in the Spanish translations.

Save the `Register_es.properties` file in the same package as `Register.properties`.

In our example application, we need to tell Struts to use a locale value of es (since we’re not in a Spanish locale) instead of the default locale value of our location (which is en). Add the following markup to index.jsp.

Specify The Locale As a URL Parameter

    <h3>Registro español</h3>
    <s:url action="registerInput" var="registerInputLinkES">
        <s:param name="request_locale">es</s:param>
    </s:url>
    <p><s:a href="%{registerInputLinkES}">Por favor, regístrese</s:a> para nuestro sorteo</p>

In the above markup we’ve added a parameter named request_locale to the URL. The value of that parameter is `es`. The Action class that responds to this URL (`Register.java`) will see that the locale is `es` and will look for property files with `_es` (for example `Register_es.properties`). It will use those property files to find the values of the property keys referenced by the view page (e.g. `personBean.firstName`).

After clicking on the above link you should see the same form as before but with the form field labels in Spanish.

If we implement the same concept by creating _es.properties versions of `global.properties` (`global_es.properties`) and `package.properties` (`package_es.properties`) then we can create a complete registration web page in Spanish. Download the finished example application for this tutorial from Github message-resource repository to see those property files and run the complete example with the registration form in Spanish.

## Summary

We’ve covered how to use message resources (resource bundles) in Struts and also introduced how Struts enables internationalization (i18n) in this tutorial. To fully understand these concepts and learn more about Struts consult the main Struts documentation.

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