如何在java程序中运行js的代码分享

import javax.script.ScriptEngine; 
import javax.script.ScriptEngineManager;
import javax.script.ScriptException; /** * 直接调用js代码 */
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\");"); // 不能调用浏览器中定义的js函数 // 错误，会抛出alert引用不存在的异常
 }catch(ScriptException e){
 e.printStackTrace();
 }
 } 
}

import java.io.FileReader; 
 import javax.script.Invocable;

 import javax.script.ScriptEngine;

 import javax.script.ScriptEngineManager; 
 /** * Java调用并执行js文件，传递参数，并活动返回值 * * @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"; // 读取js文件 

FileReader reader = new FileReader(jsFileName); // 执行指定脚本 
engine.eval(reader); 

if(engine instanceof Invocable) { 
Invocable invoke = (Invocable)engine; // 调用merge方法，并传入两个参数 

// c = merge(2, 3); 

Double c = (Double)invoke.invokeFunction("merge", 2, 3); 

System.out.println("c = " + c); 
} 

reader.close(); 

 }
}

// expression.js 
function merge(a, b) { 
 c = a * b; 
 return c; 
}