Programmatic HTMLDocument generation using Java

Question

Does anyone know how to generate an HTMLDocument object programmatically in Java without resorting to generating a String externally and then using HTMLEditorKit#read to parse it? Two reasons I ask:

Firstly my HTML generation routine needs to be very fast and I assume that parsing a string into an internal model is more costly than directly constructing this model.

Secondly, an object-oriented approach would likely result in cleaner code.

I should also mention that, for licensing reasons, I can't resort to using any libraries other than those shipped with the JVM.

Thanks, Tom

Answer 1

javax.swing.text.html has HTMLWriter and HTMLDocument class among others. I have not used them. I have used the HtmlWriter in .Net and it does exactly what you want, but the java version may not work out to be the same.

Here is the doc: http://java.sun.com/j2se/1.5.0/docs/api/javax/swing/text/html/HTMLWriter.html

Also, I can't imagine a StringBuilder being slower than building with an object layer. It seems to me that any object oriented approach would have to build the object graph AND then produce the string. The main reason not to use raw strings for this stuff is that you are sure to get encoding errors as well as other mistakes that produce malformed documents.

Option 2: You could use your favorite XML api's and produce XHTML.

Answer 2

I'd look into how JSPs work - i.e., they compile down into a servlet that is basically one huge long set of StringBuffer appends. The tags also compile down into Java code snippets. This is messy, but very very fast, and you never see this code unless you delve into Tomcat's work directory. Maybe what you want is to actually code your HTML generation from a HTML centric view like a JSP, with added tags for loops, etc, and use a similar code generation engine and compiler internally within your project.

Alternatively, just deal with the StringBuilder yourself in a utility class that has methods for "openTag", "closeTag", "openTagWithAttributes", "startTable", and so on... it could use a Builder pattern, and your code would look like:

public static void main(String[] args) {
    TableBuilder t = new TableBuilder();
    t.start().border(3).cellpadding(4).cellspacing(0).width("70%")
      .startHead().style("font-weight: bold;")
        .newRow().style("border: 2px 0px solid grey;")
          .newHeaderCell().content("Header 1")
          .newHeaderCell().colspan(2).content("Header 2")
      .end()
      .startBody()
        .newRow()
          .newCell().content("One/One")
          .newCell().rowspan(2).content("One/Two")
          .newCell().content("One/Three")
        .newRow()
          .newCell().content("Two/One")
          .newCell().content("Two/Three")
      .end()
    .end();
    System.out.println(t.toHTML());
}

Answer 3

I think manually generating your HTML via something like a StringBuilder (or directly to a stream) is going to be your best option, especially if you cannot use any external libraries.

Not being able to use any external libraries, you will suffer more in terms of speed of development rather than performance.