JavaScript: The Definitive Guide, 6th Edition

Scripting Java with Rhino

Rhino is a JavaScript interpreter written in Java and designed to make it easy to write JavaScript programs that leverage the power of the Java platform APIs. Rhino automatically handles the conversion of JavaScript primitives to Java primitives, and vice versa, so JavaScript scripts can set and query Java properties and invoke Java methods.

Obtaining Rhino

Rhino is free software from Mozilla. You can download a copy from http://www.mozilla.org/rhino/. Rhino version 1.7r2 implements ECMAScript 3 plus a number of the language extensions described in Chapter 11. Rhino is mature software and new versions are not released often. At the time of this writing, a prerelease version of 1.7r3 is available from the source repository and includes a partial implementation of ECMAScript 5.

Rhino is distributed as a JAR archive. Start it with a command line like this:

java -jar rhino1_7R2/js.jar program.js

If you omit program.js, Rhino starts an interactive shell, which is useful for trying out simple programs and one-liners.

Rhino defines a handful of important global functions that are not part of core JavaScript:

// Embedding-specific globals: Type help() at the rhino prompt for more
print(x);           // Global print function prints to the console
version(170);       // Tell Rhino we want JS 1.7 language features
load(filename,...); // Load and execute one or more files of JavaScript code
readFile(file);     // Read a text file and return its contents as a string
readUrl(url);       // Read the ...