Java编程Nashorn实例代码

public class StringFunction { 
   
  /** 
   * 字符串截取 
   */ 
  public String sub(String str, int start, int end) { 
    return str.substring(start, end); 
  } 
   
  /** 
   * 字符串拼接 
   */ 
  public String append(String... strs) { 
    StringBuilder result = new StringBuilder(strs[0]); 
    Stream.of(strs).skip(1).forEach(str -> result.append(str)); 
    return result.toString(); 
  } 
} 

public class StringNashorn { 
   
  /** 
   * Nashorn脚本引擎 
   */ 
  private ScriptEngine nashorn = new ScriptEngineManager().getEngineByName("nashorn"); 
   
  /** 
   * 执行脚本 
   */ 
  public Object execute(String script) { 
    ScriptContext scriptContext = new SimpleScriptContext(); 
    // 定义一个名为stringfunction的函数，这个函数实际对应着一个StringFunction对象 
    scriptContext.setAttribute("stringfunction", new StringFunction(), 100); 
    nashorn.setContext(scriptContext); 
     
    Object result = null; 
    try { 
      result = nashorn.eval(script); 
    } catch (ScriptException e) { 
      e.printStackTrace(); 
    } 
     
    return result; 
  } 
} 

public class NashornTest { 
   
  public static void main(String[] args) { 
    String substring = "stringfunction.sub(\"abcdefghijk\", 1, 4);"; 
    String append = "stringfunction.append(\"abc\", \"def\");"; 
     
    StringNashorn nashorn = new StringNashorn(); 
    Object subResult = nashorn.execute(substring); 
    Object appendResult = nashorn.execute(append); 
    System.out.println(subResult.toString()); 
    System.out.println(appendResult.toString()); 
  } 
} 

public class NashornTest { 
   
  public static void main(String[] args) { 
    // 脚本内用对象接收结果并打印 
    String substring = "var s1 = stringfunction.sub(\"abcdefghijk\", 1, 4);" 
        + " print(s1);"; 
    String append = "var s2 = stringfunction.append(\"abc\", \"def\");" 
        + " print(s2);"; 
     
    StringNashorn nashorn = new StringNashorn(); 
    // 这里execute不再返回对象，因为在脚本里面已经有对象接收sub和append的执行结果。 
    nashorn.execute(substring); 
    nashorn.execute(append); 
  } 
}