Java调用groovy实现原理代码实例
一、概述
Groovy is a multi-faceted language for the Java platform.
Apache Groovy是一种强大的、可选的类型化和动态语言,具有静态类型和静态编译功能,用于Java平台,目的在于通过简洁、熟悉和易于学习的语法提高开发人员的工作效率。它可以与任何Java程序顺利集成,并立即向您的应用程序提供强大的功能,包括脚本编写功能、特定于域的语言编写、运行时和编译时元编程以及函数式编程。
Groovy是基于java虚拟机的,执行文件可以是简单的脚本片段,也可以是一个完整的groovy class,对于java程序员来说,学习成本低,可以完全用java语法编写。
二、java项目执行groovy必要环境
<dependency> <groupId>org.codehaus.groovy</groupId> <artifactId>groovy-all</artifactId> <version>2.4.16</version> </dependency> <dependency> <groupId>org.kohsuke</groupId> <artifactId>groovy-sandbox</artifactId> <version>1.7</version> </dependency>
三、java项目执行groovy方式
3.1 ScriptEngineManager
groovy遵循JSR 223标准,可以使用jdk的标准接口ScriptEngineManager调用。
@org.junit.Test public void scriptEngineManager() throws ScriptException, NoSuchMethodException { ScriptEngineManager factory = new ScriptEngineManager(); // 每次生成一个engine实例 ScriptEngine engine = factory.getEngineByName("groovy"); System.**out**.println(engine.toString()); // javax.script.Bindings Bindings binding = engine.createBindings(); binding.put("date", new Date()); // 如果script文本来自文件,请首先获取文件内容 engine.eval("def getTime(){return date.getTime();}", binding); engine.eval("def sayHello(name,age){return 'Hello,I am ' + name + ',age' + age;}"); Long time = (Long) ((Invocable) engine).invokeFunction("getTime", null);// 反射到方法 System.**out**.println(time); String message = (String) ((Invocable) engine).invokeFunction("sayHello", "zhangsan", 12); System.**out**.println(message); }
((Invocable) engine).invokeFunction(方法名,…参数)
3.2 GroovyShell
直接使用GroovyShell,执行groovy脚本片段,GroovyShell每一次执行时代码时会动态将代码编译成java class,然后生成java对象在java虚拟机上执行,所以如果使用GroovyShell会造成class太多,性能较差。
@org.junit.Test public void testGroovyShell() { final String script = "Runtime.getRuntime().availableProcessors()"; Binding intBinding = new Binding(); GroovyShell shell = new GroovyShell(intBinding); final Object eval = shell.evaluate(script); System.**out**.println(eval); }
3.3 GroovyClassLoader
groovy官方提供GroovyClassLoader从文件,url或字符串中加载解析Groovy class
@org.junit.Test public void testGroovyClassLoader() throws IllegalAccessException, InstantiationException { GroovyClassLoader groovyClassLoader = new GroovyClassLoader(); String hello = "package com.szwn.util" + "class GroovyHello {" + "String sayHello(String name) {" + "print 'GroovyHello call'" + "name" + "}" + "}"; Class aClass = groovyClassLoader.parseClass(hello); GroovyObject object = (GroovyObject) aClass.newInstance(); Object o = object.invokeMethod("sayHello", "zhangsan"); System.out.println(o.toString()); }
3.4 GroovyScriptEngine
GroovyScriptEngine可以从url(文件夹,远程协议地址,jar包)等位置动态加装resource(script或则Class),同时对
编译后的class字节码进行了缓存,当文件内容更新或者文件依赖的类更新时,会自动更新缓存。
@org.junit.Test public void testGroovyScriptEngine() throws IOException, ResourceException, groovy.util.ScriptException { String url = "...(文件地址)"; GroovyScriptEngine engine = new GroovyScriptEngine(url); for (int i = 0; i < 5; i++) { Binding binding = new Binding(); binding.setVariable("index", i); // 每一次执行获取缓存Class,创建新的Script对象 Object run = engine.run("HelloWorld.groovy", binding); System.out.println(run); } }
四、安全
4.1 SecureASTCustomizer
Groovy会自动引入java.util,java.lang包,方便用户调用,但同时也增加了系统的风险。为了防止用户调用System.exit或Runtime等方法导致系统宕机,以及自定义的groovy片段代码执行死循环或调用资源超时等问题,Groovy提供了SecureASTCustomizer安全管理者和SandboxTransformer沙盒环境。
@org.junit.Test public void testAST() { final String script = "import com.alibaba.fastjson.JSONObject;JSONObject object = new JSONObject()"; // 创建SecureASTCustomizer final SecureASTCustomizer secure = new SecureASTCustomizer(); // 禁止使用闭包 secure.setClosuresAllowed(true); List<Integer> tokensBlacklist = new ArrayList<>(); // 添加关键字黑名单 while和goto tokensBlacklist.add(Types.**KEYWORD_WHILE**); tokensBlacklist.add(Types.**KEYWORD_GOTO**); secure.setTokensBlacklist(tokensBlacklist); // 设置直接导入检查 secure.setIndirectImportCheckEnabled(true); // 添加导入黑名单,用户不能导入JSONObject List<String> list = new ArrayList<>(); list.add("com.alibaba.fastjson.JSONObject"); secure.setImportsBlacklist(list); // statement 黑名单,不能使用while循环块 List<Class<? extends Statement>> statementBlacklist = new ArrayList<>(); statementBlacklist.add(WhileStatement.class); secure.setStatementsBlacklist(statementBlacklist); // 自定义CompilerConfiguration,设置AST final CompilerConfiguration config = new CompilerConfiguration(); config.addCompilationCustomizers(secure); Binding intBinding = new Binding(); GroovyShell shell = new GroovyShell(intBinding, config); final Object eval = shell.evaluate(script); System.out.println(eval); }
SecureASTCustomizer :属性
tokensBlacklist 关键字黑名单
ImportsBlacklist 导入黑名单
statementBlacklist statement 黑名单
如果代码块中出现黑名单限制的内容,则会抛出异常
4.2 SandboxTransformer
用户调用System.exit或调用Runtime的所有静态方法都会抛出SecurityException
@org.junit.Test public void testGroovySandbox() { // 自定义配置 CompilerConfiguration config = new CompilerConfiguration(); // 添加线程中断拦截器,可拦截循环体(for,while)、方法和闭包的首指令 config.addCompilationCustomizers(new ASTTransformationCustomizer(ThreadInterrupt.class)); // 添加线程中断拦截器,可中断超时线程,当前定义超时时间为3s Map<String, Object> timeoutArgs = new HashMap<>(); timeoutArgs.put("value", 3); config.addCompilationCustomizers(new ASTTransformationCustomizer(timeoutArgs, TimedInterrupt.class)); // 沙盒环境 config.addCompilationCustomizers(new SandboxTransformer()); GroovyShell sh = new GroovyShell(config); // 注册至当前线程 new NoSystemExitSandbox().register(); new NoRunTimeSandbox().register(); // 确保在每次更新缓存Class<Script>对象时候,采用不同的groovyClassLoader Script groovyScript = sh.parse("System.exit(1)"); Object run = groovyScript.run(); System.**out**.println(run); } class NoSystemExitSandbox extends GroovyInterceptor { @Override public Object onStaticCall(GroovyInterceptor.Invoker invoker, Class receiver, String method, Object... args) throws Throwable { if (receiver == System.class && method.equals("exit")) { throw new SecurityException("No call on System.exit() please"); } return super.onStaticCall(invoker, receiver, method, args); } } class NoRunTimeSandbox extends GroovyInterceptor { @Override public Object onStaticCall(GroovyInterceptor.Invoker invoker, Class receiver, String method, Object... args) throws Throwable { if (receiver == Runtime.class) { throw new SecurityException("No call on RunTime please"); } return super.onStaticCall(invoker, receiver, method, args); } }
五、groovy代码块调用java代码注意事项
5.1 java代码行/代码块
Java代码可以直接放在groovy方法体/代码块中运行
def hello = {name ->
System.out.println(name)
}
等同于
def helli = {name ->
println(name)
}
5.2 获取java对象
5.2.1 new
直接通过new 来获取
def newJavaObject(){ DpDeptCopyInfo deptCopyInfo = new DpDeptCopyInfo(); println(deptCopyInfo) } newJavaObject();
5.2.2 spring bean
不能使用@Autowired(autowired是在spring启动后注入的,此时还未加载groovy代码,故无法注入)
建议实现ApplicationContextAware接口的工具(组件)来获取spring bean
@Component public final class SpringUtils implements BeanFactoryPostProcessor { /** Spring应用上下文环境 \*/ private static ConfigurableListableBeanFactory beanFactory; @Override public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { SpringUtils.beanFactory = beanFactory; } @SuppressWarnings("unchecked") public static <T> T getBean(String name) throws BeansException { return (T) beanFactory.getBean(name); } public static <T> T getBean(Class<T> clz) throws BeansException { T result = (T) beanFactory.getBean(clz); return result; } }
例:
被调用的groovy代码
def springTransfer = {name -> println("==============================开始groovy====================================") QueryDataDaoService daoService = SpringUtils.getBean(QueryDataDaoService.class); println("对象:" + daoService) println("==============================结束groovy====================================") println("==============================返回传入参数====================================") return name } springTransfer(name)
Java代码:
@Test public void testGroovySpringTransfer() throws IOException, ResourceException, ScriptException { //获取 groovy脚本文件的绝对路径 String filePath = "文件路径"; GroovyScriptEngine engine = new GroovyScriptEngine(filePath); //执行获取缓存Class,创建新的Script对象 Object run = engine.run("SpringTransfer.groovy", "ladq"); System.out.println("执行groovy结果:" + run); }
执行结果
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