Java – How to include an html fragment in a jsp that loads at run-time

filejavajspservlets

I need to include content in a JSP without using the include directive.

It is easy to do a server-side include with with <%@include file="includeMe.htm" %> but the content of includeMe.htm gets added to the JSP before the JSP is converted into a Servlet by the container. This means that if includeMe.htm gets modified, the changes are not reflected in the generated .java Servlet file. I'm tired of going into Tomcats generated files directory to manually delete the generated java and class files or re-deploy my app every time the included file changes.

Do I need to write a code block to just read in data from the text file line by line and then write it like this?

 <%
    while( not done reading from file ) {
        String line = scanner.nextLine();
        response.getWriter().println(line);
    }  %>

Is there an easier or cleaner way?

Best Answer

Take a look at answers here. You can also use <c:import>:

2) The <jsp:include> standard action
<jsp:include page="header.jsp" />
Dynamic: adds the content from the value of the page attribute to the current page at request time. Was intended more for dynamic content coming from JSPs.
3) The <c:import> JSTL tag:
<c:import url=”http://www.example.com/foo/bar.html” />
Dynamic: adds the content from the value of the URL attribute to the current page, at request time. It works a lot like <jsp:include>, but it’s more powerful and flexible: unlike the other two includes, the <c:import> url can be from outside the web Container!

Regarding reading a file into string. If the file is small do it one line:

String content = new Scanner(new File("filename")).useDelimiter("\\Z").next();

Related Solutions

Java – How to test a class that has private methods, fields or inner classes

Update:

Some 10 years later perhaps the best way to test a private method, or any inaccessible member, is via @Jailbreak from the Manifold framework.
@Jailbreak Foo foo = new Foo();
// Direct, *type-safe* access to *all* foo's members
foo.privateMethod(x, y, z);
foo.privateField = value;
This way your code remains type-safe and readable. No design compromises, no overexposing methods and fields for the sake of tests.

If you have somewhat of a legacy Java application, and you're not allowed to change the visibility of your methods, the best way to test private methods is to use reflection.

Internally we're using helpers to get/set private and private static variables as well as invoke private and private static methods. The following patterns will let you do pretty much anything related to the private methods and fields. Of course, you can't change private static final variables through reflection.

Method method = TargetClass.getDeclaredMethod(methodName, argClasses);
method.setAccessible(true);
return method.invoke(targetObject, argObjects);

And for fields:

Field field = TargetClass.getDeclaredField(fieldName);
field.setAccessible(true);
field.set(object, value);

Notes:
1. TargetClass.getDeclaredMethod(methodName, argClasses) lets you look into private methods. The same thing applies for getDeclaredField.
2. The setAccessible(true) is required to play around with privates.

Java – Servlet for serving static content

I came up with a slightly different solution. It's a bit hack-ish, but here is the mapping:

<servlet-mapping>   
    <servlet-name>default</servlet-name>
    <url-pattern>*.html</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.jpg</url-pattern>
</servlet-mapping>
<servlet-mapping>
 <servlet-name>default</servlet-name>
    <url-pattern>*.png</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.css</url-pattern>
</servlet-mapping>
<servlet-mapping>
    <servlet-name>default</servlet-name>
    <url-pattern>*.js</url-pattern>
</servlet-mapping>

<servlet-mapping>
    <servlet-name>myAppServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

This basically just maps all content files by extension to the default servlet, and everything else to "myAppServlet".

It works in both Jetty and Tomcat.

Java – How to include an html fragment in a jsp that loads at run-time

Best Answer

2) The `<jsp:include>` standard action

3) The `<c:import>` JSTL tag:

Related Topic

Best Answer

2) The <jsp:include> standard action

3) The <c:import> JSTL tag:

Related Solutions

Java – How to test a class that has private methods, fields or inner classes

Java – Servlet for serving static content

Related Topic

2) The `<jsp:include>` standard action

3) The `<c:import>` JSTL tag: