标签：嵌入 传递 调用 ref define blog shell 参数 static
最近设计一个数据统计系统,系统中上百种数据统计维度,而且这些数据统计的指标可能随时会调整.如果基于java编码的方式逐个实现数据统计的API设计,工作量大而且维护起来成本较高;最终确定为将"数据统计"的计算部分单独分离成脚本文件(javascript,或者Groovy),非常便捷了实现了"数据统计Task" 与 "数据统计规则(计算)"解耦,且可以动态的加载和运行的能力.顺便对JAVA嵌入运行Groovy脚本做个备忘.
Java中运行Groovy,有三种比较常用的类支持:GroovyShell,GroovyClassLoader以及Java-Script引擎(JSR-223).
1) GroovyShell: 通常用来运行"script片段"或者一些零散的表达式(Expression)
2) GroovyClassLoader: 如果脚本是一个完整的文件,特别是有API类型的时候,比如有类似于JAVA的接口,面向对象设计时,通常使用GroovyClassLoader.
3) ScriptEngine: JSR-223应该是推荐的一种使用策略.规范化,而且简便.
一.GroovyShell代码样例
1) 简单的表达式执行,方法调用
/** * 简答脚本执行 * @throws Exception */ public static void evalScriptText() throws Exception{ //groovy.lang.Binding Binding binding = new Binding(); GroovyShell shell = new GroovyShell(binding); binding.setVariable("name", "zhangsan"); shell.evaluate("println ‘Hello World! I am ‘ + name;"); //在script中,声明变量,不能使用def,否则scrope不一致. shell.evaluate("date = new Date();"); Date date = (Date)binding.getVariable("date"); System.out.println("Date:" + date.getTime()); //以返回值的方式,获取script内部变量值,或者执行结果 //一个shell实例中,所有变量值,将会在此"session"中传递下去."date"可以在此后的script中获取 Long time = (Long)shell.evaluate("def time = date.getTime(); return time;"); System.out.println("Time:" + time); binding.setVariable("list", new String[]{"A","B","C"}); //invoke method String joinString = (String)shell.evaluate("def call(){return list.join(‘ - ‘)};call();"); System.out.println("Array join:" + joinString); shell = null; binding = null; }
2) 伪main方法执行.
/** * 当groovy脚本,为完整类结构时,可以通过执行main方法并传递参数的方式,启动脚本. */ public static void evalScriptAsMainMethod(){ String[] args = new String[]{"Zhangsan","10"};//main(String[] args) Binding binding = new Binding(args); GroovyShell shell = new GroovyShell(binding); shell.evaluate("static void main(String[] args){ if(args.length != 2) return;println(‘Hello,I am ‘ + args[0] + ‘,age ‘ + args[1])}"); shell = null; binding = null; }
3) 通过Shell运行具有类结构的Groovy脚本
/** * 运行完整脚本 * @throws Exception */ public static void evalScriptTextFull() throws Exception{ StringBuffer buffer = new StringBuffer(); //define API buffer.append("class User{") .append("String name;Integer age;") //.append("User(String name,Integer age){this.name = name;this.age = age};") .append("String sayHello(){return ‘Hello,I am ‘ + name + ‘,age ‘ + age;}}\n"); //Usage buffer.append("def user = new User(name:‘zhangsan‘,age:1);") .append("user.sayHello();"); //groovy.lang.Binding Binding binding = new Binding(); GroovyShell shell = new GroovyShell(binding); String message = (String)shell.evaluate(buffer.toString()); System.out.println(message); //重写main方法,默认执行 String mainMethod = "static void main(String[] args){def user = new User(name:‘lisi‘,age:12);print(user.sayHello());}"; shell.evaluate(mainMethod); shell = null; }
4) 方法执行和分部调用
/** * 以面向"过程"的方式运行脚本 * @throws Exception */ public static void evalScript() throws Exception{ Binding binding = new Binding(); GroovyShell shell = new GroovyShell(binding); //直接方法调用 //shell.parse(new File(//)) Script script = shell.parse("def join(String[] list) {return list.join(‘--‘);}"); String joinString = (String)script.invokeMethod("join", new String[]{"A1","B2","C3"}); System.out.println(joinString); ////脚本可以为任何格式,可以为main方法,也可以为普通方法 //1) def call(){...};call(); //2) call(){...}; script = shell.parse("static void main(String[] args){i = i * 2;}"); script.setProperty("i", new Integer(10)); script.run();//运行, System.out.println(script.getProperty("i")); //the same as System.out.println(script.getBinding().getVariable("i")); script = null; shell = null; }
二. GroovyClassLoader代码示例
1) 解析groovy文件
/** * from source file of *.groovy */ public static void parse() throws Exception{ GroovyClassLoader classLoader = new GroovyClassLoader(Thread.currentThread().getContextClassLoader()); File sourceFile = new File("D:\\TestGroovy.groovy"); Class testGroovyClass = classLoader.parseClass(new GroovyCodeSource(sourceFile)); GroovyObject instance = (GroovyObject)testGroovyClass.newInstance();//proxy Long time = (Long)instance.invokeMethod("getTime", new Date()); System.out.println(time); Date date = (Date)instance.invokeMethod("getDate", time); System.out.println(date.getTime()); //here instance = null; testGroovyClass = null; }
2) 如何加载已经编译的groovy文件(.class)
public static void load() throws Exception { GroovyClassLoader classLoader = new GroovyClassLoader(Thread.currentThread().getContextClassLoader()); BufferedInputStream bis = new BufferedInputStream(new FileInputStream("D:\\TestGroovy.class")); ByteArrayOutputStream bos = new ByteArrayOutputStream(); for(;;){ int i = bis.read(); if( i == -1){ break; } bos.write(i); } Class testGroovyClass = classLoader.defineClass(null, bos.toByteArray()); //instance of proxy-class //if interface API is in the classpath,you can do such as: //MyObject instance = (MyObject)testGroovyClass.newInstance() GroovyObject instance = (GroovyObject)testGroovyClass.newInstance(); Long time = (Long)instance.invokeMethod("getTime", new Date()); System.out.println(time); Date date = (Date)instance.invokeMethod("getDate", time); System.out.println(date.getTime()); //here bis.close(); bos.close(); instance = null; testGroovyClass = null; }
三. ScriptEngine
1) pom.xml依赖
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy</artifactId>
<version>2.1.6</version>
</dependency>
<dependency>
<groupId>org.codehaus.groovy</groupId>
<artifactId>groovy-jsr223</artifactId>
<version>2.1.6</version>
</dependency>
2) 代码样例
public static void evalScript() throws Exception{ ScriptEngineManager factory = new ScriptEngineManager(); //每次生成一个engine实例 ScriptEngine engine = factory.getEngineByName("groovy"); System.out.println(engine.toString()); assert engine != null; //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); System.out.println(time); String message = (String)((Invocable)engine).invokeFunction("sayHello", "zhangsan",new Integer(12)); System.out.println(message); }
需要提醒的是,在groovy中,${expression} 将会被认为一个变量,如果需要输出"$"符号,需要转义为"\$".
关于ScriptEngine更多介绍,请参考.
标签：嵌入 传递 调用 ref define blog shell 参数 static
原文地址：https://www.cnblogs.com/wpcnblog/p/9945706.html
