WAS v8.5 > Develop applications > XML applications > Use the XML API to perform operations > Precompiling

Precompiling in Java

We can use the XCompilationFactory interface and its various compile and load methods to compile an expression, query, or stylesheet in advance. The Java classes can be loaded at execution time, therefore avoiding the cost of compilation in the application run time.

• Retrieve the XCompilationFactory by calling the getCompilationFactory method on the XFactory class.

  An XCompilationFactory instance is associated with a particular XFactory instance, so they share registered schemas. If a new schema is registered with the XFactory instance; therefore, it is visible to the associated XCompilationFactory instance.

• Create a new XCompilationParameters instance by calling the XCompilationFactory newCompilationParameters method, passing in the base class name to use for the generated classes.

  Configure the parameters further using the set methods described in this table.

  Valid set methods.

  These set methods are defined in the XCompilationParameters interface and are valid for generating a precompiled executable.

  Set Methods Valid for Generating a Precompiled Executable	Description	Default
  setPackageName	Specify the package name for the generated classes. The value must be a valid Java package name.	Java default package
  setDirectoryName	Specify the directory to which the generated classes should be written. The directory must exist.	Current working directory as retrieved by calling the Java System.getProperty method with the property user.dir

  The setClassLoader method is only valid when loading the generated classes using one of the load methods. If the class loader is set at compile time, it is ignored.

• Use one of the compile methods on the XCompilationFactory, passing in the XCompilationParameters, to generate the precompiled executable.

  The compile methods use the XStaticContext just like the XFactory prepare methods to configure prepare-time settings. Note that compilation is implied when the compile methods are used; therefore, changing the use-compiler setting through the XStaticContext setUseCompiler method has no effect on these methods. If no static context is specified, the default settings are used.

Example

The following is a basic example of precompiling an XPath expression.

// Create the factory
XFactory factory = XFactory.newInstance();
               
// Get the compilation factory
XCompilationFactory compileFactory = factory.getCompilationFactory();
       
// Create the compilation parameters XCompilationParameters params = compileFactory.newCompilationParameters("MyXPath");
params.setPackageName("org.example.myxpath");
                
// Generate the compiled classes compileFactory.compileXPath("/doc/item[@id > 3000]", params);

Appropriate compile methods are available for XQuery and XSLT as well.

Related

Precompiling using the command-line tools
Loading a precompiled executable

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