ScriptEngineManager的使用说明

矫情吗；* 2023-06-26 05:49 15阅读 0赞

import java.util.ArrayList;
    import java.util.List;
    import java.util.Map;
    import java.util.TreeMap;
    
    import javax.script.Invocable;
    import javax.script.ScriptEngine;
    import javax.script.ScriptEngineManager;
    import javax.script.ScriptException;
    import javax.script.SimpleBindings;
    /**
     * ScriptEngine engine = new ScriptEngineManager().getEngineByName("nashorn");
       engine.eval(new FileReader("script.js"));
     * @author chenyuanbao
     *
     */
    public class Test {
    	public static void main(String[] args) throws ScriptException {
    		exeVar();
    		exeFor();
    		exeCondition("0.01");
    		exeCondition1("8","8");
    		try {
    			putValue();
    			callJsFunction();
    		} catch (Exception e) {
    			e.printStackTrace();
    		}
    	}
    	//java将变量导入js脚本 2的8次方
        public static void putValue() throws Exception{
            String str="Math.pow(a,b)";
            Map<String, Object>input=new TreeMap<>();
            input.put("a",2);
            input.put("b",8);
            ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
            System.out.println(engine.eval(str,new SimpleBindings(input)));
        }
        //调用js函数
    	public static void callJsFunction() throws Exception{
    		ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
            engine.eval("function add (a, b) {return a+b; }");
            Invocable jsInvoke = (Invocable) engine;
            Object res = jsInvoke.invokeFunction("add", new Object[] { 10, 5 });
            System.out.println(res);
    	}
    	public static void exeCondition1(String x,String y) throws ScriptException{
    	   	List<String> conditions = new ArrayList<>();
    	 	conditions.add("x==0");//如果写x=0 报错，x==0则正常。
    	   	conditions.add("x>0&&y<10");
    	 	conditions.add("x>=10&&y<20");
    	 	conditions.add("x>=20&&y<30");
    	 	ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
    		engine.put("x", x);
    		engine.put("y", y);
    		for(String script:conditions){
    			Boolean ret  = (Boolean) engine.eval(script);
    			System.out.println(script+"="+ret);
    		}
    	}
    	
    	public static void exeCondition(String val) throws ScriptException{
    	   	List<String> conditions = new ArrayList<>();
    	 	conditions.add("x==0");//如果写x=0 报错，x==0则正常。
    	   	conditions.add("x>0&&x<1");
    	 	conditions.add("x>=1&&x<2");
    	 	conditions.add("x>=2&&x<3");
    	 	ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
    		engine.put("x", val);
    		for(String script:conditions){
    			Boolean ret  = (Boolean) engine.eval(script);
    			System.out.println(script+"="+ret);
    		}
    	}
    	
    	public static void exeVar() throws ScriptException{
    		ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
    		Double hour = (Double) engine.eval("var date = new Date();" + "date.getHours();");
    		System.out.println("hour : " + hour);
    	}
    	public static void exeFor() throws ScriptException{
    		ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
    		engine.put("name", "abcdefg");//倒置一个字符串
    		engine.eval("var output ='' ;" + "for (i = 0; i <= name.length; i++) { " + " output = name.charAt(i) + output"
    				+ "}");
    		String name = (String) engine.get("output");
    		System.out.printf("被翻转后的字符串：%s \n", name);
    	}
    	//该函数测试Java与js对象
        public static void getObject() throws Exception{
            String str = "  var obj=new Object();     "
                + "  obj.info='hello world';   "
                + "  obj.getInfo=function(){   "
                + "        return this.info;   "
                + "  };                        ";
            ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
            engine.eval(str);
            //获取对象
            ScriptObjectMirror obj=(ScriptObjectMirror) engine.get("obj");
            //输出属性
            System.out.println(obj.get("info"));
            System.out.println(obj.get("getInfo"));
            str="obj.getInfo()";
            //执行方法
            System.out.println(engine.eval(str));
        }
      //该函数测试Java获取JS变量值的能力
        public static void getJsValue() throws Exception{
            String str = "  var msg='hello';          "
                + "  var number = 123;         "
                + "  var array=['A','B','C'];  "
                + "  var json={                "
                + "      'name':'pd',          "
                + "      'subjson':{           "
                + "           'subname':'spd'  "
                + "           ,'id':123        "
                + "           }                "
                + "      };                    ";
            ScriptEngineManager manager = new ScriptEngineManager();
    		ScriptEngine engine = manager.getEngineByName("javascript");
            //执行语句
            engine.eval(str);
            str="msg+=' world';number+=5";
            //再次执行
            engine.eval(str);
            //获取js变量msg（String类型）
            System.out.println(engine.get("msg"));
            //获取js变量msg（int类型）
            System.out.println(engine.get("number"));
            //获取js变量array（数组）
            ScriptObjectMirror array=(ScriptObjectMirror) engine.get("array");
            //getSlot（int index）函数用于获取下标为index的值
            System.out.println(array.getSlot(0));
            //获取js变量json（json类型）
            ScriptObjectMirror json=(ScriptObjectMirror) engine.get("json");
            //get（String key）函数用于键key的值
            System.out.println(json.get("name"));
            //获取js变量subjson（嵌套json类型）
            ScriptObjectMirror subjson=(ScriptObjectMirror)json.get("subjson");
            System.out.println(subjson.get("subname"));
        }
        //参考文档
    }