JAVA嵌入运行Groovy脚本
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
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
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);
}
3) 实际案例，Java调用groovy文件里面的方法，并传递参数
static void simpleTest() throws IOException, InstantiationException, IllegalAccessException, ResourceException, ScriptException{
String[] roots = new String[] { "src/main/groovy/com/mobile263/billing/groovy/" };
//通过指定的roots来初始化GroovyScriptEngine
GroovyScriptEngine gse = new GroovyScriptEngine(roots);
GroovyObject groovyObject = (GroovyObject) gse.loadScriptByName("TestScript.groovy").newInstance();
String result = (String) groovyObject.invokeMethod("output", "hello");
System.out.println(result);
}
class TestScript {
static String output(def str){
println str;
return "hello"+str;
}
}