java6调用运行javascript代码

import javax.script.*;
import static java.lang.System.*;

public class FirstJavaScript {
public static void main(String args[]) {
ScriptEngineManager manager = new ScriptEngineManager();
// 得到javascript脚本引擎
ScriptEngine engine = manager.getEngineByName("javascript");
try {
Double hour = (Double) engine.eval("21+3+3/3");
Double hour1 = (Double)engine.eval("var date = new Date();" +"date.getMonth();");
System.out.println(hour);
System.out.println(hour1);
} catch (ScriptException e) {
err.println(e);
}
}
}