Java8中执行js脚本

代码中除了callJSFunctionFromFile函数，其他均转载于文章JDK1.8中如何用ScriptEngine动态执行JS

import jdk.nashorn.api.scripting.ScriptObjectMirror;
import javax.script.Invocable;
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import javax.script.SimpleBindings;
import java.io.FileReader;
import java.util.Map;
import java.util.TreeMap;public class JSEngine {
public static ScriptEngine engine;
public static String str; public static void getValues() throws Exception{
str = " var msg='hello'; "
+ " var number = 123; "
+ " var array=['A','B','C']; "
+ " var json={ "
+ " 'name':'pd', "
+ " 'subjson':{ "
+ " 'subname':'spd' "
+ " ,'id':123 "
+ " } "
+ " }; ";
engine.eval(str);
str="msg+=' world';number+=5";
System.out.println(engine.get("msg"));
System.out.println(engine.get("number"));
//获取数组
ScriptObjectMirror array = (ScriptObjectMirror) engine.get("array");
System.out.println(array.getSlot(0)); ScriptObjectMirror json = (ScriptObjectMirror) engine.get("json");
System.out.println(json.get("name")); //json嵌套
ScriptObjectMirror subjson = (ScriptObjectMirror) json.get("subjson");
System.out.println(subjson.get("subname"));
} public static void getObject() throws Exception{
str = " var obj=new Object(); "
+ " obj.info='hello world'; "
+ " obj.getInfo=function(){ "
+ " return this.info; "
+ " }; ";
engine.eval(str);
ScriptObjectMirror obj = (ScriptObjectMirror) engine.get("obj");
System.out.println(obj.get("info"));
System.out.println(obj.get("getInfo"));
str = "obj.getInfo()";
System.out.println(engine.eval(str));
} //给js传递变量
public static void putValue() throws Exception{
str = "Math.pow(a,b)";
Map<String,Object> input = new TreeMap<>();
input.put("a",2);
input.put("b",8);
System.out.println(engine.eval(str,new SimpleBindings(input)));
} //调用js函数
public static void callJSFunction() throws Exception{
str = "function add (a, b) {return a+b; }";
//执行js脚本定义函数
engine.eval(str);
Invocable invocable = (Invocable) engine;
Object res = invocable.invokeFunction("add",new Object[]{2,3});
System.out.println(res); } //读取js文件，执行函数;易变业务使用脚本编写，这样即使修改脚本，也不需重新部署java程序
public static void callJSFunctionFromFile() throws Exception{
//执行js
while (true){
//模拟执行期间add.js被修改
Thread.sleep(5000);
engine.eval(new FileReader("e:\\add.js"));
Invocable invocable = (Invocable) engine;
Object res = invocable.invokeFunction("add",new Object[]{2,3});
System.out.println(res);
}
} public static void main(String[] args) throws Exception{
ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
engine = scriptEngineManager.getEngineByName("javascript");
getValues();
getObject();
putValue();
callJSFunction();
callJSFunctionFromFile();
}}