Setting Properties for Groups of JSP Pages

Deactivating EL Expression Evaluation

Declaring Page Encodings

Defining Implicit Includes

Eliminating Extra White Space

Setting Properties for Groups of JSP Pages

It is possible to specify certain properties for a group of JSP pages:

• Expression language evaluation

• Treatment of scripting elements (seeDisabling Scripting)

• Page encoding

• Automatic prelude and coda includes

A JSP property group is defined by naming the group and specifying oneor more URL patterns; all the properties in the group apply to theresources that match any of the URL patterns. If a resource matches URLpatterns in more than one group, the pattern that is most specific applies.

To define a property group in a deployment descriptor using NetBeans IDE, followthese steps:

1. In NetBeans IDE, expand your project’s folder in the Projects pane.

2. Expand the Web Pages node and then the WEB-INF node.

3. Double-clickweb.xml to open it in the editor pane.

4. Click Pages at the top of the editor pane.

5. Click Add JSP Property Group.

6. In the Add JSP Property Group dialog:

   1. Enter a name for the JSP property group in the Display Name field.

   2. Enter a URL pattern (a regular expression, such as*.jsp) or click Browse to indicate to which page or set of pages to apply the properties specified by the JSP property group.

   3. Click OK.

Instead of performing the preceding steps, you can define a JSP property groupby editing the XML by hand using NetBeans IDE by doing thefollowing:

1. Perform steps 1 through 3 in the preceding set of steps.

2. Click XML at the top of the editor pane.

3. Include ajsp-config element if the deployment descriptor doesn’t already have one.

4. Add ajsp-property-group element inside thejsp-config element.

5. Add adisplay-name element inside thejsp-property-group element and give it a name.

6. Add aurl-pattern element inside thejsp-property-group element and give it a URL pattern (a regular expression, such as*.jsp).

The following sections discuss the properties and explain how they are interpreted forvarious combinations of group properties, individual page directives, and web application deployment descriptorversions.

Deactivating EL Expression Evaluation

Each JSP page has a default mode for EL expression evaluation. The defaultvalue varies depending on the version of the web application deployment descriptor. Thedefault mode for JSP pages delivered with a Servlet 2.4 descriptor is toevaluate EL expressions; this automatically provides the default that most applications want. Thedefault mode for JSP pages delivered using a descriptor from Servlet 2.3 orbefore is to ignore EL expressions; this provides backward compatibility. For tag files (seeEncapsulating Reusable Content Using Tag Files), the default is to always evaluate expressions.

You can override the default mode through theisELIgnored attribute of thepage directive in JSP pages and through theisELIgnored attribute of thetagdirective in tag files. You can also explicitly change the default mode bydoing one of the following:

• If you are using the Pages section of theweb.xml editor pane in NetBeans IDE:

  1. Expand the JSP Property Group node.

  2. Select the Ignore Expression Language check box.

• If you are editing theweb.xml file by hand, add anel-ignored element to thejsp-property-group element in the deployment descriptor and set it to true.

Table 5-8 summarizes the EL evaluation settings for JSP pages.

Table 5-8 EL Evaluation Settings for JSP Pages

Table 5-9 summarizes the EL evaluation settings for tag files.

Table 5-9 EL Evaluation Settings for Tag Files

Declaring Page Encodings

You set the page encoding of a group of JSP pages using theJSP property group configuration in the deployment descriptor by doing one of thefollowing:

• If you are using the Pages section of theweb.xml editor pane in NetBeans IDE:

  1. Expand the JSP Property Group node.

  2. Enter the page encoding in the Page Encoding field.

• If you are editing theweb.xml file by hand, add apage-encoding element to thejsp-property-group element in the deployment descriptor and set it to one of the valid character encoding codes, which are the same as those accepted by thepageEncoding attribute of thepage directive.

A translation-time error results if you define the page encoding of a JSPpage with one value in the JSP configuration element and then giveit a different value in apageEncoding directive.

Defining Implicit Includes

You can implicitly include preludes and codas for a group of JSP pagesby adding items to the Include Preludes and Codas lists. Their values arecontext-relative paths that must correspond to elements in the web application. When theelements are present, the given paths are automatically included (as in anincludedirective) at the beginning and end, respectively, of each JSP page in theproperty group. When there is more than one include or coda element ina group, they are included in the order they appear. When more thanone JSP property group applies to a JSP page, the corresponding elements willbe processed in the same order as they appear in the JSP configurationsection.

For example, the Duke’s Bookstore application uses the files/template/prelude.jspf and/template/coda.jspfto include the banner and other boilerplate in each screen. To add thesefiles to the Duke’s Bookstore property group using the deployment descriptor, follow these steps:

1. In NetBeans IDE, expand your project’s folder in the Projects pane.

2. Expand the Web Pages node and then the WEB-INF node.

3. Double-clickweb.xml to open it in the editor pane.

4. Click Pages at the top of the editor pane.

5. Add a new JSP property group if you haven’t already (seeSetting Properties for Groups of JSP Pages) and give it the namebookstore2 and the URL pattern*.jsp.

6. Expand the JSP Property Group node.

7. Click the Browse button to the right of the Include Preludes field to locate the file that you want to include at the beginning of all pages matching the pattern in the URL pattern field. In this case, you want the/template/prelude.jspf file.

8. Click the Browse button to the right of the Include Codas field to locate the file that you want to include at the end of all pages matching the URL pattern. In this case, you want the/template/coda.jspf file.

Instead of performing the preceding steps, you can add preludes and codas byediting the XML by hand using NetBeans IDE by doing the following:

1. Perform steps 1 through 3 in the preceding set of steps.

2. Click XML at the top of the editor pane.

3. Add a new JSP property group (seeSetting Properties for Groups of JSP Pages) and give it the namebookstore2 and URL pattern*.jsp.

4. Add aninclude-prelude element to thejsp-property-group element and give it the name of the file to include, in this case,/template/prelude.jspf.

5. Add aninclude-coda element to thejsp-property-group element and give it the name of the file to include, in this case,/template/coda.jspf.

Preludes and codas can put the included code only at the beginningand end of each file. For a more flexible approach to building pagesout of content chunks, seeA Template Tag Library.

Eliminating Extra White Space

White space included in the template text of JSP pages is preserved bydefault. This can have undesirable effects. For example, a carriage return added afterataglib directive would be added to the response output as an extraline.

If you want to eliminate the extra white space from the page,you can add atrim-directive-whitespaces element to ajsp-property-group element in the deploymentdescriptor and set it totrue.

To set thetrim-directive-whitespaces element to true using NetBeans 5.5, do the following:

1. Open the deployment descriptor file in the editor.

2. Click the Pages button at the top of the editor.

3. Select a JSP property group.

4. Select the Trim Directive Whitespaces check box.

5. Save the deployment descriptor.

Alternatively, a page author can set the value of thetrimDirectiveWhitespaces attributeof thepage directive to true or false. This will override the valuespecified in the deployment descriptor.

Custom tag authors can eliminate white space from the output generated by atag file by setting thetrimDirectiveWhiteSpace attribute of thetag directive to true.

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