java调用js脚本语言

电玩女神 2024-02-19 18:41 71阅读 0赞

在我们开发的过程中，可能有这么一种情况，**在java中需要取调用js方法完成一些事情**。那么什么时候可能出现这种情况呢。比如我们使用爬虫模拟登录别的网站，但有些网站前台使用js对密码进行了加密处理，那么就需要在java中进行调用js方法，完成js密码的加密操作。

**在这篇博客记录如下几种调用方式：**

1、java执行js文件

2、js方法写在java代码中，然后执行

3、脚本引擎自身的作用域和全局作用域

4、在js中调用java类

实现：

**1、java执行js文件**

|- 执行js文件中的方法

|- 向js方法中传递参数

|- 获取到js方法执行后的返回值

**1.1 js方法的定义**

function showUser(name) {
        // console.info("haha");
        return "haha[" + name + "],我返回了值";
    }

**1.2 java代码**

@Test
    	public void invokedJsFile() throws Exception {
    		try (InputStream is = JavaInvokeJsTest.class.getResourceAsStream("script.js")) {
    			ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
    			// 拿到js脚本引擎
    			ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("js");
    			InputStreamReader isr = new InputStreamReader(is);
    			scriptEngine.eval(isr);
    			if (scriptEngine instanceof Invocable) {
    				Invocable invocable = (Invocable) scriptEngine;
    				/**
    				 * 调用showUser方法，javascript engine 作为参数传入showUser方法中
    				 */
    				String result = (String) invocable.invokeFunction("showUser", "javascript engine");
    				System.out.println("the result is : " + result);
    			}
    		}
    	}

**1.3 结果**  
![aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81Njk1LzE4ZDliYmFmLTU2MDktM2U3ZC04NGM2LWQzODkzNTZjMDdjZS5wbmc][]

**2、js方法写在java代码中**

**2.1 java代码**

@Test
    	public void invokedScriptMethod() throws Exception {
    		ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
    		ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("js");
    		scriptEngine.put("userName", "张三");
    		String script = "function showName(flag){ if(flag){ return userName + ',你好.' ;} else { return '不满足条件';} }";
    		scriptEngine.eval(script);
    		Invocable invocable = (Invocable) scriptEngine;
    		String result = (String) invocable.invokeFunction("showName", true);
    		System.out.println(result);
    	}

**2.2结果**  
![aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81Njk3L2QyZTFhZmUyLTkxZjAtMzQ2OC1iZDhlLWFmNGQ0OWNjNjA0MC5wbmc][]

**3.脚本引擎自身的作用域和全局作用域**

|- ScriptEngineManager的put方法设置全局作用域

|- ScriptEngine的put设置脚本自身的作用域

@Test
    	public void testScriptScope() throws Exception {
    		ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
    
    		ScriptEngine scriptEngine1 = scriptEngineManager.getEngineByName("js");
    		// 向脚本的全局作用域中设置值
    		scriptEngineManager.put("globalVal", "全局");
    		// 此值时脚本自身的作用域
    		scriptEngine1.put("userName", "张三");
    		String script1 = "function showName(){ return '获取全局作用域globalVal的值:['+globalVal + ']: 获取自身作用域username的值:[' + userName  + '].' ; }";
    		scriptEngine1.eval(script1);
    		Invocable invocable1 = (Invocable) scriptEngine1;
    		String result1 = (String) invocable1.invokeFunction("showName");
    		System.out.println(result1);
    
    		ScriptEngine scriptEngine2 = scriptEngineManager.getEngineByName("js");
    
    		scriptEngine2.put("userName", "李四");
    		String script2 = "function showName(){ return '获取全局作用域globalVal的值:['+globalVal + ']: 获取自身作用域username的值:[' + userName  + '].' ; }";
    		scriptEngine2.eval(script2);
    		Invocable invocable2 = (Invocable) scriptEngine2;
    		String result2 = (String) invocable2.invokeFunction("showName");
    		System.out.println(result2);
    
    		System.out.println("=====================================");
    		System.out.println("全局作用域的值：");
    		System.out.println("===> gloableVal:" + scriptEngineManager.get("globalVal"));
    		System.out.println("脚本作用域1的值：");
    		System.out.println("===> userName:" + scriptEngine1.get("userName"));
    		System.out.println("脚本作用域2的值：");
    		System.out.println("===> userName:" + scriptEngine2.get("userName"));
    		System.out.println("=====================================");
    
    	}

**结果：**  
![aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81Njk5L2I5ODFlNDM2LWFkYjMtMzA1Ni04MWVhLWI2MGVlYTkwZTYwZC5wbmc][]

**4、在js中调用java类**

|- 实现效果,js中将java的list集合中的元素改变，并加上一个new java.util.Date()的值

**4.1 Java代码**

|- String script 中写出了js中如何调用java方法。

@Test
    	public void testJava() throws Exception {
    		ScriptEngineManager scriptEngineManager = new ScriptEngineManager();
    		ScriptEngine scriptEngine = scriptEngineManager.getEngineByName("js");
    		List<String> list = new ArrayList<>(3);
    		list.add("张三");
    		list.add("李四");
    		list.add("wangwu");
    
    		String script = "function show(list){ for(var i=0;i<list.size();i++){ list.set(i,list.get(i)+':'+i); };list.add(new java.util.Date().toString());}";
    		scriptEngine.eval(script);
    
    		Invocable invocable = (Invocable) scriptEngine;
    		invocable.invokeFunction("show", list);
    
    		System.out.println(list);
    	}

**4.2 结果**  
![aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81NzAxLzJmMTViMDFkLThhYTctMzJkMi04ODg2LWMxNGQxYTlhYmU1Ni5wbmc][]

一般情况下，在java中调用js方法的情况少，不过了解一下也是有好处的。

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[aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81Njk3L2QyZTFhZmUyLTkxZjAtMzQ2OC1iZDhlLWFmNGQ0OWNjNjA0MC5wbmc]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/2b0ecbea19cd486793981bc9434cf6e8.png
[aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81Njk5L2I5ODFlNDM2LWFkYjMtMzA1Ni04MWVhLWI2MGVlYTkwZTYwZC5wbmc]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/095e8b7c4e8e4be092607a968a084ef0.png
[aHR0cDovL2RsMi5pdGV5ZS5jb20vdXBsb2FkL2F0dGFjaG1lbnQvMDEyOC81NzAxLzJmMTViMDFkLThhYTctMzJkMi04ODg2LWMxNGQxYTlhYmU1Ni5wbmc]: https://image.dandelioncloud.cn/pgy_files/images/2024/01/29/f2736dea53324402b116f784cd2bf087.png