What are the characteristics of Java dynamic script Groovy
这篇文章主要为大家展示了"Java动态脚本Groovy的特性是什么"，内容简而易懂，条理清晰，希望能够帮助大家解决疑惑，下面让小编带领大家一起研究并学习一下"Java动态脚本Groovy的特性是什么"这篇文章吧。
1.Groovy特性
可将java代码在Groovy脚本动态编码、代码被修改达到不重启服务的目的（类似于热部署）
2.核心涉及
ClassLoader：就是类的装载器，它使JVM可以动态的载入Java类，JVM并不需要知道从什么地方（本地文件、网络等）载入Java类，这些都由ClassLoader完成。
GroovyClassLoader：动态地加载一个脚本并执行它的行为。GroovyClassLoader是一个定制的类装载器，负责解释加载Java类中用到的Groovy类。
3.Java与Groovy转换
第一步：引入Groovy依赖
org.codehaus.groovy groovy 2.5.14 第二步：创建interface接口声明方法
public interface CallAnalysis { default void load() { }}第三步：在resources目录下创建.groovy文件
package groovyimport com.example.groovy.testgroovy.task.CallAnalysisimport groovy.util.logging.Slf4j@Slf4jclass CallAnalysisImpl implements CallAnalysis{ @Override void load() { log.info("我被Groovy脚本加载...") }}第四步：创建Groovy脚本装载类，动态解析脚本为Class
package com.example.groovy.testgroovy.task;import groovy.lang.GroovyClassLoader;public class GroovyUtils { private final static ClassLoader classLoader = GroovyUtils.class.getClassLoader();//获取当前类装载器 //ClassLoader：就是类的装载器，它使JVM可以动态的载入Java类，JVM并不需要知道从什么地方（本地文件、网络等）载入Java类，这些都由ClassLoader完成。 public final static GroovyClassLoader groovyClassLoader = new GroovyClassLoader(classLoader); //GroovyClassLoader：负责在运行时编译groovy源代码为Class的工作，从而使Groovy实现了将groovy源代码动态加载为Class的功能。 /** * . * 获取实例化对象 * @param script groovy脚本内容 * @param * @return * @throws IllegalAccessException * @throws InstantiationException */ public static T instanceTaskGroovyScript(String script) throws IllegalAccessException, InstantiationException { Class taskClz = groovyClassLoader.parseClass(script); T instance = (T) taskClz.newInstance(); return instance; }}第五步：读取脚本内容，执行脚本
package com.example.groovy.testgroovy.task;import lombok.extern.slf4j.Slf4j;import org.apache.commons.io.FileUtils;import org.springframework.stereotype.Component;import java.io.File;import java.io.IOException;@Slf4j@Componentpublic class CallAnalysisGroovyTask { /** * . * 读取脚本内容 * * @return */ public static String getGroovy() { String context = ""; try { String path = "E:\\IDEAFile\\testgroovy\\src\\main\\resources\\groovy\\CallAnalysisImpl.groovy"; context = FileUtils.readFileToString(new File(path));//将脚本内容转为字符串 } catch (IOException e) { log.error("file is not found[{}]", e); } return context; } /** * . * 执行groovy脚本 * * @param script */ public static void execGroovy(String script) { try { CallAnalysis objClass = GroovyUtils.instanceTaskGroovyScript(script);//获取实例对象 objClass.load();//调用脚本方法 } catch (Exception t) { log.error("execGroovy file {} error", script); } } /** * . * main方法 * @param args */ public static void main(String[] args) { System.out.println("=================="); CallAnalysisGroovyTask task = new CallAnalysisGroovyTask(); String script = task.getGroovy();//获取脚本 execGroovy(script);//实例化脚本，执行方法 System.out.println("=================="); }}
4. Groovy Feature Verification
Use Groovy scripting features to modify data in real time without restarting services
Step 1: Modify the previous Groovy script data. Store in database table, load script dynamically
@Slf4jclass CallAnalysisImpl implements CallAnalysis { private int anInt = 10; private int bnInt = 10; @Override void load() { log.info ("Current Class:[{}]", this.getClass().getName()) log.info ("I was loaded by Groovy script... ") log.info ("Calculation result:[{}]", (anInt + bnInt)) }} Step 2: Add and query Groovy scripts to database tables, dynamically load and execute
/** * . * Read scripts and perform warehousing operations * * @return */ @GetMapping("/saveScript") public String saveScript() { String scriptStr = callAnalysisGroovyTask.getGroovy(); Script = newScript();//Entity class object script.setScript(scriptStr);//Script content script.setRuleId("1");//rule id script.setScriptName("Demo 1");//script name service.save(script); return "Added successfully"; } /** * . * Get scripts dynamically from database tables * * @param ruleId rule id * @return Script content */ @GetMapping("/groovy") public String groovy(final String ruleId) { Script scr = scriptService.findScriptByRuleId(ruleId);//query by rule id String scriptStr = scr.getScript(); callAnalysisGroovyTask.execGroovy(scriptStr); return scriptStr; }
Add results:
Query results, console execution results:
Step 3: Modify the table data value several times and view the execution result.
That's all for Java Dynamic Script Groovy, thanks for reading! I believe that everyone has a certain understanding, hope to share the content to help everyone, if you still want to learn more knowledge, welcome to pay attention to the industry information channel!
