Java和Js之间的调用时基于ScriptEngineManager类,这个类是jdk8新增的:
import java.io.File; import java.util.ArrayList; import java.util.List; import javax.script.Bindings; import javax.script.Invocable; import javax.script.ScriptContext; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.SimpleScriptContext; import org.junit.Test; public class JavaScriptFunction { @Test public void print() throws Exception{ ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); engine.eval("print(‘hello word!!‘)"); } @Test public void obj() throws Exception { ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); StringBuffer script = new StringBuffer(); script.append("var obj = new Object();"); script.append("obj.hello = function(name){print(‘hello, ‘+name);}"); //执行这段script脚本 engine.eval(script.toString()); // javax.script.Invocable 是一个可选的接口 // 检查你的script engine 接口是否已实现! // 注意:JavaScript engine实现了Invocable接口 Invocable inv = (Invocable) engine; // 获取我们想调用那个方法所属的js对象 Object obj = engine.get("obj"); // 执行obj对象的名为hello的方法 inv.invokeMethod(obj, "hello", "Script Method !!" ); } @Test public void file() throws Exception{ ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); engine.eval(new java.io.FileReader(new File("F:/test/test.js"))); Invocable inv = (Invocable) engine; Object obj = engine.get("obj"); inv.invokeMethod(obj, "name", "知道了" ); } /** * 脚本变量 * @throws Exception */ @Test public void scriptVar() throws Exception{ ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); File file = new File("F:/test/test.txt"); //将File对象f直接注入到js脚本中并可以作为全局变量使用 engine.put("files", file); engine.eval("print(files.getPath());print(files.getName());"); } /** * 使用Script实现java接口 * @throws Exception */ public void runnableImpl() throws Exception{ ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("JavaScript"); // String里定义一段JavaScript代码脚本 String script = "function run() { print(‘run called‘); }"; // 执行这个脚本 engine.eval(script); // 从脚本引擎中获取Runnable接口对象(实例). 该接口方法由具有相匹配名称的脚本函数实现。 Invocable inv = (Invocable) engine; // 在上面的脚本中,我们已经实现了Runnable接口的run()方法 Runnable runnable = inv.getInterface(Runnable.class); // 启动一个线程运行上面的实现了runnable接口的script脚本 Thread thread = new Thread(runnable); thread.start(); } /** * 脚本引擎的多个scope * @throws Exception */ @Test public void multiScopes() throws Exception{ ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("nashorn"); // 打印全局变量 "x" engine.put("x", "hello word!!"); engine.eval("print(x);"); // 上面的代码会打印"hello word!!" // 现在,传入另一个不同的script context ScriptContext context = new SimpleScriptContext(); //新的Script context绑定ScriptContext的ENGINE_SCOPE Bindings bindings = context.getBindings(ScriptContext.ENGINE_SCOPE); // 增加一个新变脸到新的范围 engineScope 中 bindings.put("x", "word hello!!"); // 执行同一个脚本 - 但这次传入一个不同的script context engine.eval("print(x);", bindings); engine.eval("print(x);"); } public static void main(String[] args) throws Exception { new JavaScriptFunction().runnableImpl(); List list = new ArrayList(); list.add("1"); list.add("1"); list.add("1"); for (Object object : list) { System.out.println(object); } } }
运用Java中的封装技术将运行js脚本程序进行封装:
import java.io.FileNotFoundException; import java.io.FileReader; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; /** * 运行脚本 * @author Ruby * */ public class RunScript { private ScriptEngineManager manager = new ScriptEngineManager(); private ScriptEngine engine; private String fileName; public RunScript(String fileName){ engine = manager.getEngineByName("JavaScript"); this.fileName = fileName; } /** * 设置变量 * @param varName * @param obj */ public void setVar(String varName, Object obj){ engine.put(varName, obj); } /** * 启动脚本 * @throws FileNotFoundException * @throws ScriptException */ public void start() throws FileNotFoundException, ScriptException{ engine.eval(new FileReader(fileName)); } }
测试
将Logger对象注入到js对象中,那么在js文件中就可以使用java中的Logger对象了:
public static void main(String[] args) throws Exception { RunScript rs = new RunScript("D:\test.js"); rs.setVar("Logger", Logger.getLogger(ConsoleListener.class)); rs.start(); }
扩展:
使用ScriptEngineManager类判断JSON字符串是否合法:
ScriptEngineManager sem = new ScriptEngineManager (); ScriptEngine se = sem.getEngineByName ("js"); String jsonstr = "({name: 1, obj: 3,[dd]})"; try { System.out.println (se.eval (jsonstr)); } catch (ScriptException e) { System.out.println ("json格式有误"); }
其他方式:
package util; import com.alibaba.fastjson.JSONException; import com.alibaba.fastjson.JSONObject; public class Test { public static void main(String[] args) { try { JSONObject.parse("{‘a‘:1 ‘b‘:1}"); } catch (JSONException e) { System.out.println("JSON字符串错误"); } } }
原文地址:https://www.cnblogs.com/xiejn/p/11969858.html
时间: 2024-10-11 20:40:40