java 和groovy 可以放在同一项目 java调用groovy脚本

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新新人类 2023-09-04 23:31:24

文章标签 java shell javascript ViewUI System 文章分类 Java 后端开发

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.

官方参考文档：http://docs.groovy-lang.org/latest/html/documentation/guide-integrating.html

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;
}

GroovyShell是一种性能较低的方式，因为每次都需要创建shell和script，这也意味着每次都需要对expression进行“编译”（JAVA Class）。

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");//文本内容的源代码
	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"\$".

这是一种性能较高的方式，engine我们可以声明为全局实例，是线程安全的。每次调用时只需要创建新的Binndings即可，此外如果脚本已经编译过（首次执行之后）其Class将会被缓存，则此后不需要再次编译。

关于ScriptEngine更多介绍,请参考.

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