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See the License for the specific language governing permissions and limitations under the License.--><html><head> <title>Package Documentation for org.apache.struts.util Package</title></head><body bgcolor="white">The Utilities package provides a variety of families of classes,to solve problems that are commonly encountered in building web applications.<br><br><a name="doc.Description"></a><div align="center"> <a href="#doc.Intro">[Introduction]</a> <a href="#doc.Beans">[Beans]</a> <a href="#doc.Utilities">[Servlet Utilities]</a> <a href="#doc.Messages">[Message Resources]</a></div><hr><a name="doc.Intro"></a><h3>Introduction</h3><p>The Struts Utilities Package offers several families of classes that assist in solving commonly encountered problems when building web applications. Most of the classes in this package do not rely on the controller servlet framework, or the custom tag libraries, so they are also suitable for general Java application programming. The following families are included:</p><ul> <li><a href="#doc.Beans">Beans</a> - A small set of utility beans useful for encapsulating form elements.</li> <li><a href="#doc.Utilities">Servlet Utilities</a> - A set of classes useful for working with servlet-related classes.</li> <li><a href="#doc.Messages">Message Resources</a> - A family of classes that features access to internationalized message strings based on a message key coupled with a <code>java.util.Locale</code> object representing a particular user's preferred language.</li></ul><hr><a name="doc.Beans"></a><h3>Beans</h3><p> The <code>ImageButtonBean</code> is a simple JavaBean to encapsulate the request parameters sent for an HTML input element of type image. The <code>LabelValueBean</code> is a simple JavaBean to represent label-value pairs, especially useful for html option elements.</p><hr><a name="doc.Utilities"></a><h3>Servlet Utilities</h3><p> The <code>RequestUtils</code> is a general purpose utility methods related to processing a servlet request. The <code>ResponseUtils</code> is a general purpose utility methods related to generating a servlet response. The <code>ServletContextWriter</code> is a PrintWriter implementation that uses the logging facilities of a <code>javax.servlet.ServletContext</code> to output its results.</p><hr><a name="doc.Messages"></a><h3>Message Resources</h3><h5>Background</h5><p>Modern applications often include the requirement to support multiple languages, for users who prefer to interact in a language other than the default language configured on the server platform. In addition, sentences often need to be constructed, with dynamic content whose placement in the message depends on the standard sentence structure in that particular language.</p><p>The standard Java platform includes a family of classes (<code>java.util.ResourceBundle</code>) designed to support looking up message strings based on a standard "key". The resource bundle classes automatically access a Java class (or properties file) that is named with a naming convention that includes the Locale to which messages in that class (or file) pertain. However, this selection is based only on the default Locale of the server platform, and cannot be adjusted on a per-user basis as required for an internationalized web application.</p><p>Struts includes a family of classes (<code>org.apache.struts.util.MessageResources</code>) that extends the basic approach to looking up message strings by key, allowing you to optionally specify a Locale along with the key. In this way, you can build applications that let your users select which Locale they wish to operate within, and then look up messages in that language - using the same message keys no matter what language is selected.</p><p>In addition to supporting dynamic selection of a Locale for message lookup, the <code>MessageResources</code> family of classes optionally allow you to specify up to four parameter replacement objects, which are used to replace the parameter placeholders "{0}" through "{3}" in the retrieved message. This replacement uses the facilities of the standard Java <code>java.text.MessageFormat</code> class, which supports many extended formatting capabilities as well.</p><p>For more information about internationalized messages, consult the following resources in your Java Development Kit documentation bundle:</p><ul> <li><em>Internationalization Info</em> - General information on Java's standard support for internationalized applications can be found at <code><$JAVA_HOME/docs/guide/internat/index.html></code>. The "Internationalization Overview" section includes useful information about Locales, localized resources, message formatting, and other relevant topics.</li> <li><em>Internationalization Tutorial</em> - The Java Language Tutorial has a comprehensive trail covering internationalization, available at: <a href="http://java.sun.com/docs/books/tutorial/i18n/index.html"> http://java.sun.com/docs/books/tutorial/i18n/index.html</a>.</li> <li><em>Javadoc APIs</em> - You will want to consult the Javadoc API documentation for the following standard Java classes: <ul> <li><code>java.text.MessageFormat</code> <li><code>java.util.ResourceBundle</code> <li><code>java.util.PropertyResourceBundle</code> <li><code>java.util.Properties</code> - See the documentation for the <code>load()</code> method for the valid syntax of properties files that you prepare.</li> </ul></li></ul><h5>Using the Standard MessageResources Implementation</h5><p>The standard <code>MessageResources</code> implementation provided by the Struts library uses Java properties files to initialize message strings, in a manner very similar to that supported by the <code>java.util.PropertyResourceBundle</code> class. The following steps are required to use these facilities in your Java application.</p><p>First, prepare a Java properties file for each language (or Locale) in which you wish to support your messages. The filenames you use must conform to the naming convention for property resource bundles, as described in the documentation referenced above. Be sure you use the same message keys in each⌨️ 快捷键说明
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