Java调用JS/TS与JS/TS调用Java完全指南

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import javax.script.*;
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ScriptEngineManager manager = new ScriptEngineManager();
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ScriptEngine engine = manager.getEngineByName("nashorn"); // 或 "js" / "JavaScript"

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<dependency>
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    <groupId>org.graalvm.js</groupId>
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    <artifactId>js</artifactId>
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    <version>23.0.1</version>
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</dependency>
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<dependency>
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    <groupId>org.graalvm.js</groupId>
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    <artifactId>js-scriptengine</artifactId>
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    <version>23.0.1</version>
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</dependency>

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ScriptEngine engine = new ScriptEngineManager().getEngineByName("graal.js");

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// Java 侧的服务类
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public class UserService {
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    public String getUserName(Long id) {
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        return "user_" + id;
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    }
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    public boolean isVip(Long id) {
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        return id != null && id % 2 == 0;
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    }
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}

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// 注入并调用
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UserService service = new UserService();
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engine.put("userService", service);
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engine.eval("""
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        function checkUser(id) {
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            var name = userService.getUserName(id);   // 调用 Java 方法
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            var vip  = userService.isVip(id);
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            return name + (vip ? ' [VIP]' : '');
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        }
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        """);
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Object result = ((Invocable) engine).invokeFunction("checkUser", 10086L);
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System.out.println(result); // user_10086 [VIP]

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Object json = engine.eval("JSON.stringify({id: 1, name: 'iphone', price: 6999.0});");
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// 用 Jackson 解析成 Java 对象
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Product product = new ObjectMapper().readValue(json.toString(), Product.class);
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System.out.println(product.getName()); // iphone

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String json = "{\"id\":2,\"name\":\"macbook\"}";
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Object result = engine.eval(
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    "var p = JSON.parse(" + "'" + json + "'" + ");" +
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    "p.name + ' 价格 ' + (p.price || '未知');"
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);
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System.out.println(result);

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var MathUtils;
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(function (MathUtils) {
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    function add(a, b) { return a + b; }
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    MathUtils.add = add;
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    function multiply(a, b) { return a * b; }
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    MathUtils.multiply = multiply;
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    function formatPrice(price) { return "¥" + price.toFixed(2); }
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    MathUtils.formatPrice = formatPrice;
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})(MathUtils || (MathUtils = {}));

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String script = """
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        var System = Java.type("java.lang.System");
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        var Math = Java.type("java.lang.Math");
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        System.out.println("from JS: " + Math.pow(2, 10));
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        var list = new (Java.type("java.util.ArrayList"))();
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        list.add("a");
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        System.out.println(list.size());
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        """;
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engine.eval(script);

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// 定义一个 Java 接口：public interface Calculator { int calc(int x, int y); }
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var Calculator = Java.type("com.example.Calculator");
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// 用 JS 对象实现接口
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var addCalculator = new Calculator({
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    calc: function(x, y) {
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        return x + y;
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    }
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});
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// 使用这个"JS实现的Java对象"
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print(addCalculator.calc(3, 4)); // 7

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var Runnable = Java.type("java.lang.Runnable");
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var MyTask = Java.extend(Runnable, {
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    run: function() {
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        print("task executed!");
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    }
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});
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var task = new MyTask();
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var Thread = Java.type("java.lang.Thread");
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new Thread(task).start();   // JS 实现的 Runnable 丢给 Java 线程池执行

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// Java 侧：定义函数式接口 + 注入服务对象
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@FunctionalInterface
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public interface GreetHandler {
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    String greet(String name);
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}

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engine.put("greetService", (GreetHandler) name -> "Hello " + name); // 注入 Java lambda
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engine.eval("""
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        // JS 里调用注入的 Java 服务
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        var msg = greetService.greet("JS");
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        print(msg);                     // Hello JS
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        // 再把 JS 函数通过全局变量暴露给 Java
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        var jsHandler = function(n) { return "From JS: " + n; };
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        engine.put("jsCallback", jsHandler);   // Java 可以拿到这个函数
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        """);

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engine.eval("function add(a, b) { return a + b; }");
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Invocable invocable = (Invocable) engine;
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// 把 JS 函数适配成 Java 接口 Calculator
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Calculator calc = invocable.getInterface(Calculator.class);
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System.out.println(calc.calc(2, 3)); // 5