java程式中運行js__js

jdk

1.6版本中增加了ScriptEngine可以直接運行js代碼

1、直接寫js代碼

import javax.script.ScriptEngine; 

import javax.script.ScriptEngineManager;

import javax.script.ScriptException;   /**  * 直接調用js代碼  */

public class ScriptEngineTest {    

public static void main(String[] args) { 

  ScriptEngineManager manager = new ScriptEngineManager();

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

     try{              engine.eval("var a=3; var b=4;print (a+b);");         // engine.eval("alert(\"js alert\");");    // 不能呼叫瀏覽器中定義的js函數 // 錯誤，會拋出alert引用不存在的異常

 }catch(ScriptException e){ e.printStackTrace(); } }   }

2、調用function

import java.io.FileReader;   import javax.script.Invocable; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager;   /**  * Java調用並執行js檔案，傳遞參數，並活動傳回值  *   * @author manjushri  */ public class ScriptEngineTest {    public static void main(String[] args) throws Exception {   ScriptEngineManager manager = new ScriptEngineManager();   ScriptEngine engine = manager.getEngineByName("javascript");     String jsFileName = "expression.js";   // 讀取js檔案   FileReader reader = new FileReader(jsFileName);   // 執行指定指令碼   engine.eval(reader);   if(engine instanceof Invocable) {    Invocable invoke = (Invocable)engine;    // 調用merge方法，並傳入兩個參數    // c = merge(2, 3);    Double c = (Double)invoke.invokeFunction("merge", 2, 3);    System.out.println("c = " + c);   }   reader.close();    }}

js檔案

// expression.js 

function merge(a, b) { 

 c = a * b; 

 return c; 

}