Java动态编译Java代码，运行在内存中，并执行

package com.compile.shell; import com.alibaba.fastjson.JSONObject; import com.compile.executor.JavaShellExecutor; import javax.tools.*; import java.io.File; import java.net.URL; import java.net.URLClassLoader; import java.util.ArrayList; import java.util.List; /** * Compile动态执行java的String代码到内存中并执行 * 1.创建 URLClassLoader 类加载器 * 2.获取当前执行的classpath的所有jar包的路径 * 3.通过java的ToolProvider创建JavaCompile，用来执行class源文件 * 4.创建DiagnosticCollector用来执行获取执行失败的错误结果 * 5.添加动态执行的编译环境 options 是个集合，添加内容，字符集，classpath等 * 6.传入JavaFileObject的java文件，是个集合，创建JavaSourceObject实现这个接口，Kind.SOURCE.extension = '.java' * 7.创建任务并执行 * 8.获取执行完成后的返回JavaClassObject类 * 9.创建DynamicClassLoader来加载类 ，defineClass这个方法 * * @Description: * @Auther: wjx * @Date: 2019/1/18 14:55 */ public class DynamicEngine extends JavaShellExecutor { private static DynamicEngine dynamicEngine; /** * 单例模式 * * @return */ public static DynamicEngine getInstance() { if (dynamicEngine == null) { synchronized (DynamicEngine.class) { if (dynamicEngine == null) { dynamicEngine = new DynamicEngine(); } } } return dynamicEngine; } //创建动态加载jar包 private URLClassLoader classLoader; //当前的classpath环境 private String classpath; private DynamicEngine() { //获取类加载器 this.classLoader = (URLClassLoader) this.getClass().getClassLoader(); this.buildClasspath(); } private void buildClasspath() { //初始化classpath为null this.classpath = null; StringBuilder sb = new StringBuilder(); for (URL url : this.classLoader.getURLs()) { String f = url.getFile(); sb.append(f).append(File.pathSeparator); } this.classpath = sb.toString(); } public Object javaCodeToObject(String className, String javaCode) { //记录编译起始时间 long startTime = System.currentTimeMillis(); //通过java工具获取编译的compile JavaCompiler compiler = ToolProvider.getSystemJavaCompiler(); //创建DiagnosticCollector对象 DiagnosticCollector<JavaFileObject> diagnosticCollector = new DiagnosticCollector<>(); //建立一个用于保存java文件管理器ClassFileManage //每一个文件被保存在JavaClassObject的类里面 ClassFileManager fileManager = new ClassFileManager(compiler.getStandardFileManager(null, null, null)); //使用编译选项可以默认编译行为，编译选项是一个String的Iterable集合 List<String> options = new ArrayList<>(); options.add("-encoding"); options.add("UTF-8"); options.add("-classpath"); options.add(this.classpath); //传递源文件，是一个JavaFileObject的集合 List<JavaFileObject> fileObjectList = new ArrayList<>(); fileObjectList.add(new JavaSourceObject(className, javaCode)); //创建任务 JavaCompiler.CompilationTask task = compiler.getTask(null, fileManager, diagnosticCollector, options, null, fileObjectList); //执行编译 Boolean call = task.call(); if (call) { //编译成功 System.out.println("编译成功"); } else { //编译失败 System.out.println("编译失败"); String error = null; for (Diagnostic diagnostic : diagnosticCollector.getDiagnostics()) { error += compilePrint(diagnostic); } throw new RuntimeException(error); } return fileManager.getJavaClassObject(); } /** * @param diagnostic * @return * @MethodName : compilePrint * @Description : 输出编译错误信息 */ private String compilePrint(Diagnostic diagnostic) { System.out.println("Code:" + diagnostic.getCode()); System.out.println("Kind:" + diagnostic.getKind()); System.out.println("Position:" + diagnostic.getPosition()); System.out.println("Start Position:" + diagnostic.getStartPosition()); System.out.println("End Position:" + diagnostic.getEndPosition()); System.out.println("Source:" + diagnostic.getSource()); System.out.println("Message:" + diagnostic.getMessage(null)); System.out.println("LineNumber:" + diagnostic.getLineNumber()); System.out.println("ColumnNumber:" + diagnostic.getColumnNumber()); StringBuffer res = new StringBuffer(); res.append("Code:[" + diagnostic.getCode() + "]\n"); res.append("Kind:[" + diagnostic.getKind() + "]\n"); res.append("Position:[" + diagnostic.getPosition() + "]\n"); res.append("Start Position:[" + diagnostic.getStartPosition() + "]\n"); res.append("End Position:[" + diagnostic.getEndPosition() + "]\n"); res.append("Source:[" + diagnostic.getSource() + "]\n"); res.append("Message:[" + diagnostic.getMessage(null) + "]\n"); res.append("LineNumber:[" + diagnostic.getLineNumber() + "]\n"); res.append("ColumnNumber:[" + diagnostic.getColumnNumber() + "]\n"); return res.toString(); } /** * 创建一个新的ClassLoader * * @param ruleName */ public void createNewClassLoader(String ruleName) { try { DynamicClassLoader dynamicClassLoader = new DynamicClassLoader(this.classLoader); DataEventFactory.eventClassLoaders.put(ruleName, dynamicClassLoader); } catch (Exception e) { e.printStackTrace(); } } }