小编典典

您可以看到如何传递所有参数：

ScriptEngineManager manager = new ScriptEngineManager();

ScriptEngine engine = manager.getEngineByName("JavaScript");

engine.put("artist", artist);

...

您将使用读取回值

ScriptEngine.get(...)

粘合的最后一点是用函数声明包围用户的表达式，并编写一个调用函数并将结果分配给众所周知的变量的表达式。

因此，开始实验，让我们有一个功能来测试表达式：

private static void printResult(final ScriptEngine jsEngine, String name, String expr) throws ScriptException {

Object result = jsEngine.eval(expr);

System.out.println(name + " result: " + result + "; expr: " + expr);

}

现在让我们称之为：

public static void main(String[] args) throws Exception {

ScriptEngineManager sem = new ScriptEngineManager();

ScriptEngine jsEngine = sem.getEngineByName("JavaScript");

printResult(jsEngine, "Hello World", "'Hello World'");

printResult(jsEngine, "Simple Math", "123 + 456");

}

这将产生：

Hello World result: Hello World; expr: 'Hello World'

Simple Math result: 579.0; expr: 123 + 456

现在让我们尝试一下您的用例：

public static void main(String[] args) throws Exception {

ScriptEngineManager sem = new ScriptEngineManager();

ScriptEngine jsEngine = sem.getEngineByName("JavaScript");

String expr = "artist + '-' + album + (disktotal > 1 ? ('-D' + diskno) : '')";

jsEngine.put("artist", "U2");

jsEngine.put("album", "The Joshua Tree");

jsEngine.put("disktotal", 1);

jsEngine.put("diskno", 1);

printResult(jsEngine, "Single Disk", expr);

jsEngine.put("artist", "Tori Amos");

jsEngine.put("album", "To Venus and Back");

jsEngine.put("disktotal", 2);

jsEngine.put("diskno", 2);

printResult(jsEngine, "Muti-Disk", expr);

}

产生结果：

Single Disk result: U2-The Joshua Tree; expr: ...

Muti-Disk result: Tori Amos-To Venus and Back-D2; expr: ...

请注意，托里(Tori)的末尾是“ D2”。

2020-09-28