Java使用ScriptEngine动态执行代码(附Java几种动态执行代码比较)

for (item : list) {

     x = x + item;

}

while (x lt 10 ) {

     x = x + 2 ;

}

String regular= "function regular(args1,args2,args3){................}" ;

ScriptEngine engine = new ScriptEngineManager().getEngineByName( "javascript" );

try {

     engine.eval(regular);

     if (engine instanceof Invocable) {

         Invocable invoke = (Invocable) engine;

         String result = (String) invoke.invokeFunction(

                 "regular" ,

                 args1,

                 args2,

                 args3);

         System.out.println(result);

         } else {

             System.out.println( "error" );

         }

     }

} catch (ScriptException e) {

     System.out.println( "表达式runtime错误:" + e.getMessage());

}

import java.lang.*;

import java.util.Arrays;

import java.util.List;

import javax.script.Invocable;

import javax.script.ScriptEngine;

import javax.script.ScriptEngineManager;

public class ScriptEngineTest {

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

     ScriptEngineManager sem = new ScriptEngineManager();

     ScriptEngine engine = sem.getEngineByName( "javascript" );     //python or jython,

<pre name= "code" class = "html" >   //向上下文中存入变量

    engine.put( "msg" , "just a test" );

    //定义类user

    String str = "msg += '!!!';var user = {name:'tom',age:23,hobbies:['football','basketball']}; " ;

    engine.eval(str);

    //从上下文引擎中取值

    String msg = (String) engine.get( "msg" );

    String name = (String) engine.get( "name" );

    String[] hb = engine.get( "hb" );

    System.out.println(msg);

    System.out.println(name + ":" + hb[ 0 ]);

    //定义数学函数

    engine.eval( "function add (a, b) {c = a + b; return c; }" );

     //取得调用接口

     Invocable jsInvoke = (Invocable) engine;

   //定义加法函数

   Object result1 = jsInvoke.invokeFunction( "add" , new Object[] { 10 , 5 });

   System.out.println(result1);

   //调用加法函数,注意参数传递的方法

   Adder adder = jsInvoke.getInterface(Adder. class );

   int result2 = adder.add( 10 , 35 );

   System.out.println(result2);

   //定义run()函数

   engine.eval( "function run() {print('HdhCmsTestjava2s测试数据');}" );

   Invocable invokeEngine = (Invocable) engine;

   Runnable runner = invokeEngine.getInterface(Runnable. class );

   //定义线程运行之

   Thread t = new Thread(runner);

   t.start();

   t.join();

   //导入其他java包

   String jsCode = "importPackage(java.util);

   var list2 = Arrays.asList([ 'A' , 'B' , 'C' ]); ";

   engine.eval(jsCode);

   List<String> list2 = (List<String>) engine.get( "list2" );

   for (String val : list2) { System.out.println(val);}

   }

}