javax.script包：如何导入JavaScript文件？

Question

我正在使用javax.script包在Java应用程序中运行外部JavaScript文件。

如何在不使用Java代码的情况下将一个JavaScript文件导入另一个JavaScript文件？

Answer 1

当你说不使用java代码时，我不完全确定你的意思，但这是一个纯粹的javascript工作（虽然它调用java）：

importPackage(java.io);
function loadJs(name, user) {
    println("Loading " + name);
    var f = new File(name);
    var br = new BufferedReader(new FileReader(f));
    var line = null;
    var script = "";
    while((line = br.readLine())!=null) {
        script += line;
    }
    println(script);
    eval(script);
    hello(user);
}

...当然，我有一个名为（例如 c：/temp/hellouser.js ）的文件，其中包含：

function hello(name) { print('Hello, ' + name); }

我使用groovy脚本测试了脚本：

import javax.script.*;

sem = new ScriptEngineManager();
engine = sem.getEngineByExtension("js");
script1 = """
importPackage(java.io);
function loadJs(name, user) {
    println("Loading " + name);
    var f = new File(name);
    var br = new BufferedReader(new FileReader(f));
    var line = null;
    var script = "";
    while((line = br.readLine())!=null) {
        script += line;
    }
    println(script);
    eval(script);
    hello(user);
}
""";

engine.eval(script1);
Object obj = engine.get("obj");
Invocable inv = (Invocable) engine;
inv.invokeFunction("loadJs", "c:/temp/hellouser.js", "Nicholas");

，输出结果为：

  

加载c：/temp/hellouser.js

     

function hello（name）{print（'Hello，'+ name）; }

     

你好，尼古拉斯

我希望这大约是你要找的......

===========================更新================ ===========

这是一个清理版本，扩展了Rhino脚本引擎工厂（因为引擎本身是最终的）：

import javax.script.Bindings;
import javax.script.ScriptContext;
import javax.script.ScriptEngine;
import javax.script.ScriptException;

import com.sun.script.javascript.RhinoScriptEngineFactory;

/**
 * <p>Title: LoadEnabledRhinoEngineFactory</p>
 * <p>Description: Adding a loadJs function to the standard JS engine</p> 
 * <p>Company: Helios Development Group LLC</p>
 * @author Whitehead (nwhitehead AT heliosdev DOT org)
 * <p><code>org.helios.apmrouter.js.LoadEnabledRhinoEngineFactory</code></p>
 */

public class LoadEnabledRhinoEngineFactory extends RhinoScriptEngineFactory {

    /** The load script source */
    public static final String LOAD_JS = 
        "importPackage(java.io); " +
        "var script = ''; " +
        "var ctx = null; " +
        "function loadScript(name) { " +
            "var f = new File(name); " +
            "var br = new BufferedReader(new FileReader(f)); " +
            "var line = null; " +           
            "while((line = br.readLine())!=null) { " +
                "    script += line; " +
            "} " +
            "_e_ngine.eval(script);" + 
        "} ";

    /**
     * {@inheritDoc}
     * @see com.sun.script.javascript.RhinoScriptEngineFactory#getScriptEngine()
     */
    @Override
    public ScriptEngine getScriptEngine() {
        ScriptEngine se = super.getScriptEngine();
        Bindings b = se.createBindings();
        b.put("_e_ngine", se);
        se.setBindings(b, ScriptContext.GLOBAL_SCOPE);
        try {
            se.eval(LOAD_JS);
        } catch (ScriptException e) {
            throw new RuntimeException(e);
        }
        return se;
    }

现在，loadScript(fileName)是引擎的一部分，你可以用JS干净地调用它：

loadScript('c:/temp/hellouser.js'); 
hello('Nicholas');"

或者我在Java中测试过：

ScriptEngine se = new LoadEnabledRhinoEngineFactory().getScriptEngine();
try {
    se.eval("loadScript('c:/temp/hellouser.js'); hello('Nicholas');");
} catch (Exception e) {
    e.printStackTrace(System.err);
}

干杯。