Examples of org.apache.commons.chain.Command

org.apache.commons.chain.Command
A {@link Command} encapsulates a unit of processing work to beperformed, whose purpose is to examine and/or modify the state of a transaction that is represented by a {@link Context}. Individual {@link Command}s can be assembled into a {@link Chain}, which allows them to either complete the required processing or delegate further processing to the next {@link Command} in the {@link Chain}.

{@link Command} implementations should be designed in a thread-safemanner, suitable for inclusion in multiple {@link Chain}s that might be processed by different threads simultaneously. In general, this implies that {@link Command} classes should not maintain state information ininstance variables. Instead, state information should be maintained via suitable modifications to the attributes of the {@link Context} that ispassed to the execute() command.

{@link Command} implementations typically retrieve and store stateinformation in the {@link Context} instance that is passed as a parameterto the execute() method, using particular keys into the Map that can be acquired via Context.getAttributes(). To improve interoperability of {@link Command} implementations, a useful design pattern is to expose thekey values used as JavaBeans properties of the {@link Command}implementation class itself. For example, a {@link Command} that requiresan input and an output key might implement the following properties:
```
 private String inputKey = "input"; public String getInputKey() { return (this.inputKey); } public void setInputKey(String inputKey) { this.inputKey = inputKey; } private String outputKey = "output"; public String getOutputKey() { return (this.outputKey); } public void setOutputKey(String outputKey) { this.outputKey = outputKey; } 
```
And the operation of accessing the "input" information in the context would be executed by calling:
```
 String input = (String) context.get(getInputKey()); 
```
instead of hard coding the attribute name. The use of the "Key" suffix on such property names is a useful convention to identify properties being used in this fashion, as opposed to JavaBeans properties that simply configure the internal operation of this {@link Command}.
@author Craig R. McClanahan @version $Revision: 1.5 $ $Date: 2004/02/25 00:01:07 $

            catalog = factory.getCatalog();
        }


        ServletWebContext context =
            new ServletWebContext(getServletContext(), request, response);
        Command command = catalog.getCommand("COMMAND_MAPPER");
        try {
            command.execute(context);
        } catch (Exception e) {
            throw new ServletException(e);
        }


    }

View Full Code Here

     * instance is <code>true</code>
     * @throws Exception if and error occurs in the looked-up Command.
     */
    public boolean execute(Context context) throws Exception {


        Command command = getCommand(context);
        if (command != null) {
            boolean result = (command.execute(context));
            if (isIgnoreExecuteResult()) {
                return false;
            }
            return result;
        } else {

View Full Code Here

     * unless the <code>optional</code> property is <code>false</code>, in which
     * case <code>IllegalArgumentException</code> will be thrown.
     */
    public boolean postprocess(Context context, Exception exception) {


        Command command = getCommand(context);
        if (command != null) {
            if (command instanceof Filter) {
                boolean result = (((Filter) command).postprocess(context, exception));
                if (isIgnorePostprocessResult()) {
                    return false;

View Full Code Here

     */
    protected Command getCommand(Context context) {


        Catalog catalog = getCatalog(context);


        Command command = null;
        String name = getCommandName(context);
        if (name != null) {
            command = catalog.getCommand(name);
            if ((command == null) && !isOptional()) {
                if (catalogName == null) {

View Full Code Here

            throw new IllegalStateException(
                "Neither 'method' nor 'methodKey' properties are defined "
            );
        }


        Command command = getCommand(context);


        if (command != null) {
            Method methodObject = extractMethod(command, context);
            Object obj = methodObject.invoke(command, getArguments(context));
            Boolean result = (Boolean)obj;

View Full Code Here

        Object top = digester.peek(0);
        if ((top == null)
            || !(top instanceof Command)) {
            return;
        }
        Command command = (Command) top;


        // Is the next object a Catalog or a Chain?
        Object next = digester.peek(1);
        if (next == null) {
            return;

View Full Code Here

    // Test the ability to add commands
    public void testCommands() {


        checkCommandCount(0);


        Command command1 = new NonDelegatingCommand("1");
        chain.addCommand(command1);
        checkCommandCount(1);


        Command command2 = new DelegatingCommand("2");
        chain.addCommand(command2);
        checkCommandCount(2);


        Command command3 = new ExceptionCommand("3");
        chain.addCommand(command3);
        checkCommandCount(3);


    }

View Full Code Here




    // Verify the number of configured commands
    protected void checkCommandCount(int expected) {
        if (chain instanceof ChainBase) {
            Command commands[] = ((ChainBase) chain).getCommands();
            assertNotNull("getCommands() returned a non-null array",
                          commands);
            assertEquals("Correct command count", expected, commands.length);
        }
    }

View Full Code Here

        // Check overall command count
        load(DEFAULT_XML);
        checkCommandCount(17);


        // Check individual single command instances
        Command command = null;


        command = catalog.getCommand("AddingCommand");
        assertNotNull(command);
        assertTrue(command instanceof AddingCommand);

View Full Code Here

     * <p>Test <code>getCatalog()</code> method.</p>
     */
    public void testCatalogIdentifier() {


        Catalog defaultCatalog = new CatalogBase();
        Command defaultFoo = new NonDelegatingCommand();
        defaultCatalog.addCommand("foo", defaultFoo);
        Command fallback = new NonDelegatingCommand();
        defaultCatalog.addCommand("noSuchCatalog:fallback", fallback);


        factory.setCatalog(defaultCatalog);


        Catalog specificCatalog = new CatalogBase();
        Command specificFoo = new NonDelegatingCommand();
        specificCatalog.addCommand("foo", specificFoo);
        factory.addCatalog("specific", specificCatalog);


        Command command = factory.getCommand("foo");
        assertSame(defaultFoo, command);


        command = factory.getCommand("specific:foo");
        assertSame(specificFoo, command);

View Full Code Here

0 1 2 3 4 5 6 7 8 9

TOP

Related Classes of org.apache.commons.chain.Command

ch.nerdin.generators.testdata.BeanFactory

com.azaptree.services.command.http.handler.CommandServiceHandler

com.azaptree.services.command.impl.CommandServiceImpl

com.google.code.mgnlgroovy.scheduler.CommandJob

org.apache.commons.chain.apps.example.ExampleServlet

org.apache.commons.chain.config.ConfigParser2TestCase

org.apache.commons.chain.config.ConfigParserTestCase

org.apache.commons.chain.config.ConfigRegisterRule

org.apache.commons.chain.generic.DispatchLookupCommand

org.apache.commons.chain.generic.LookupCommand

All source code are property of their respective owners. Java is a trademark of Sun Microsystems, Inc and owned by ORACLE Inc. Contact coftware#gmail.com.