net.java.html

Class BrwsrCtx

java.lang.Object

net.java.html.BrwsrCtx

All Implemented Interfaces:

Executor

public final class BrwsrCtx
extends Object
implements Executor

Represents context where the net.java.html.json.Model and other objects operate in. The context is usually a particular HTML page in a browser. The context is also associated with the actual HTML technology in the HTML page - there is likely to be different context for knockout.js and different one for angular. Since version 1.1 the content of contexts can be selected by registering implementations under specific technology identifiers and requesting them during construction of the context.

Author:

Jaroslav Tulach

Field Summary

Fields

Modifier and Type	Field and Description
static BrwsrCtx	EMPTY Dummy context without binding to any real browser or technology.

Method Summary

Modifier and Type	Method and Description
void	execute(Runnable exec) Runs provided code in the context of this BrwsrCtx.
static BrwsrCtx	findDefault(Class<?> requestor) Seeks for the default context that is associated with the requesting class.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

EMPTY

public static final BrwsrCtx EMPTY

Dummy context without binding to any real browser or technology. Useful for simple unit testing of behavior of various business logic code.

Method Detail

findDefault

public static BrwsrCtx findDefault(Class<?> requestor)

Seeks for the default context that is associated with the requesting class. If no suitable context is found, a warning message is printed and BrwsrCtx.EMPTY context is returned. One can enter a context by calling BrwsrCtx.execute(java.lang.Runnable).

Parameters:

requestor - the class that makes the request

Returns:

appropriate context for the request

execute

public final void execute(Runnable exec)

Runs provided code in the context of this BrwsrCtx. If there is an Executor registered in the context it is used to perform the given code. While the code exec is running the value of BrwsrCtx.findDefault(java.lang.Class) returns this. If the executor supports a single thread execution policy, it may execute the runnable later (in such case this method returns immediately). If the call to this method is done on the right thread, the runnable should be executed synchronously.

Example Using a Timer

public final class Periodicaly extends TimerTask {
    private final BrwsrCtx ctx;
    private int counter;

    private Periodicaly(BrwsrCtx ctx) {
        // remember the browser context and use it later
        this.ctx = ctx;
        this.counter = 0;
    }

    @Override
    public void run() {
        // arrives on wrong thread, needs to be re-scheduled
        ctx.execute(new Runnable() {
            @Override
            public void run() {
                codeThatNeedsToBeRunInABrowserEnvironment();
            }
        });
    }

    // called when your page is ready
    public static void onPageLoad(String... args) throws Exception {
        // the context at the time of page initialization
        BrwsrCtx initialCtx = BrwsrCtx.findDefault(Periodicaly.class);
        // the task that is associated with context
        Periodicaly task = new Periodicaly(initialCtx);
        // creates a new timer
        Timer t = new Timer("Move the box");
        // run the task every 100ms
        t.scheduleAtFixedRate(task, 0, 100);
    }

    @JavaScriptBody(args = { "a", "b" }, body = "return a + b")
    private static native int plus(int a, int b);

    void codeThatNeedsToBeRunInABrowserEnvironment() {
        // invokes JavaScript function in the browser environment
        counter = plus(counter, 1);
    }
}

Specified by:

execute in interface Executor

Parameters:

exec - the code to execute

Since:

0.7.6