There is little reason to create your own ActionServlet class, although you are still free to do so. The following web. The next step that needs to be performed to configure the Struts controller servlet in the deployment descriptor is to configure the servlet mapping. This is done using the servlet-mapping element.
The following partial deployment descriptor illustrates how to combine the servlet-mapping element with the servlet element shown previously:. Notice that the value in the servlet-name element within the servlet element must match the value in the servlet-name element within the servlet-mapping element.
This tells the web container that the ActionServlet should service all requests having an extension of. This is a good time to digress for a moment and discuss how the URLs that a user types into a browser are mapped to the correct web application and servlet. When a web application is installed in a container, the container is responsible for assigning a ServletContext to it.
There is a single instance of a ServletContext object for each web application deployed in a container. The ServletContext provides an external view of the web container environment for a servlet. A servlet can use the ServletContext object to gain access to external resources, log events, and store attributes and objects that other servlet instances in the same context can access.
Because a servlet is associated with a specific web application, all requests that begin with a specific request path known as the context path are routed to the web application associated with that servlet.
When a web container receives a client request, it must determine the correct web application to forward it to. The web container determines this by matching the URL with the longest context path that matches an installed web application. For example, suppose that there are two web applications installed in a container.
Once the container determines the correct context or web application, it must determine which servlet in the web application should process the request. The web container uses the request URL, minus the context path, to determine the path that will be used to map the request to the correct servlet. The container recursively tries to match the longest path prefix. The servlet that contains the longest match, if any, is selected. If the URL path contains an extension—for example,.
The extension is defined as the part of the segment after the last dot. If none of the previous rules produces a match, the container attempts to use a default servlet, if one is configured. Otherwise, the request returns an error response. The concept of extension mappings was mentioned in Step 3 of the matching guidelines. There is another type of mapping that can be used, known as path mapping.
Using the earlier Storefront servlet mapping, the following partial web. As was briefly discussed in Chapter 3 , the Struts 1. In previous versions of the framework, you specified a relative path to the single Struts configuration file using the config initialization parameter.
The next section discusses the initialization parameters that can be configured for a servlet. Initialization parameters are used to make configuration options available to a servlet. This allows the developer to declaratively affect the runtime environment of the servlet. Initialization parameters are configured within the servlet element using init-param elements, as shown in the following web.
For example, the previous web deployment descriptor included initialization parameters for a host and port. If you were using EJB, this might be a way to include the server connection information. First you configure the servlet. Here you give the servlet a name, and writes the class name of the servlet. In the above example, all URL's ending in. What you will use depends on what the servlet does.
You can pass parameters to a servlet from the web. The init parameters of a servlet can only be accessed by that servlet. Here is how you configure them in the web. SimpleTagSupport class and override doTag method. The important point to note is that we should have setter methods for the attributes we need for the tag.
So we will define two setter methods — setFormat String format and setNumber String number. SimpleTagSupport provide methods through which we can get JspWriter object and write data to the response. We will use DecimalFormat class to generate the formatted string and then write it to response.
The final implementation is given below. Notice that I am catching exception thrown by format method and then throwing SkipPageException to prevent further loading of the JSP page. Notice the URI element, we will have to define it in our deployment descriptor file.
Also notice the attributes format and number that are required. We will include the jsp custom tag library in web application using jsp-config and taglib elements like below. All the configuration is done now and we can use it in the JSP page. The JSP response page is showing the formatted number, similarly we can create more jsp custom tag handler classes. Now in my existing MVC application, I already have.
Should I add another. How should I use? Like this:. Then you can reference that JSP anywhere you want to use one of those tags, as follow works well in a template if you use Tiles or Sitemesh for instance. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more.
0コメント