Java动态编译-JDK自带工具类.docx

Java动态编译-JDK自带工具类package pile;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.IOException;import java.io.OutputStream;import java.io.PrintWriter;import java.io.StringWriter;import .URI;import .URL;import .URLClassLoader;import java.util.ArrayList;import java.util.List;import javax.tools.Diagnostic;import javax.tools.DiagnosticCollector;import javax.tools.FileObject;import javax.tools.ForwardingJavaFileManager;import javax.tools.JavaCompiler;import javax.tools.JavaFileObject;import javax.tools.JavaFileObject.Kind;import javax.tools.SimpleJavaFileObject;import javax.tools.StandardJavaFileManager;import javax.tools.ToolProvider;public class MemoryCompiler static class MemoryClassLoader extends URLClassLoader MemoryClassLoader() super(new URL0);public Class defineMemoryClass(String name, byte b) return super.defineClass(name, b, 0, b.length);public static void main(String args) throws InstantiationException,IllegalAccessException StringWriter sw = new StringWriter();PrintWriter pw = new PrintWriter(sw);pw.println(public class A);pw.println(public String toString();pw.println(return Test;);pw.println();pw.println();Class c = getInstance().compile(A, sw.toString();System.out.println(c);Object o = c.newInstance();System.out.println(o);private static MemoryCompiler instance = new MemoryCompiler();private MemoryClassLoader classloader = new MemoryClassLoader();private String classpath = System.getProperty(java.class.path);private String encoding = System.getProperty(file.encoding);public static MemoryCompiler getInstance() return instance;private MemoryCompiler() ClassLoader cl = MemoryClassLoader.class.getClassLoader();if (cl instanceof URLClassLoader) StringBuilder sb = new StringBuilder();for (URL url : (URLClassLoader) cl).getURLs() String p = url.getFile();sb.append(p).append(File.pathSeparator);this.classpath = sb.toString();public Class compile(final String classname, final String source) return compile(classname, source, null);public Class compile(final String classname, final String source,final String encoding) final ByteArrayOutputStream classbytes = new ByteArrayOutputStream();JavaCompiler javaCompiler = ToolProvider.getSystemJavaCompiler();DiagnosticCollector diagnostics = new DiagnosticCollector();StandardJavaFileManager fileManager = javaCompiler.getStandardFileManager(diagnostics, null, null);List options = new ArrayList();options.add(-encoding);if (encoding != null) options.add(encoding); else options.add(this.encoding);options.add(-classpath);options.add(this.classpath);List jfiles = new ArrayList();jfiles.add(new SimpleJavaFileObject(URI.create(string:/+ classname.replace(., /)+ JavaFileObject.Kind.SOURCE.extension),JavaFileObject.Kind.SOURCE) Overridepublic CharSequence getCharContent(boolean ignoreEncodingErrors) return source;);JavaCompiler.CompilationTask task = javaCompiler.getTask(null,new ForwardingJavaFileManager(fileManager) Overridepublic JavaFileObject getJavaFileForOutput(Location location, String className, Kind kind,FileObject sibling) throws IOException return new SimpleJavaFileObject(URI.create(string:/+ classname.replace(., /)+ kind.extension), kind) Overridepublic OutputStream openOutputStream()throws IOException return classbytes;, diagnostics, options, null, jfiles);/ 编译源程序boolean success = task.call();if (success) Class clazz = classloader.defineMemoryClass(classname,classbytes.toByteArray();return clazz; else throw new IllegalArgumentException(compileError(diagnostics);private String compileError(DiagnosticCollector diagnostics) StringBuilder sb = new StringBuilder();for (Diagnostic diagnostic : diagnostics.getDiagnostics() sb.append(compileError(diagnostic).append(n);return sb.toString();private String compileError(Diagnostic diagnostic) StringBuilder sb = new StringBuilder();sb.append(Code: + diagnostic.getCode() + n);sb.append(Kind: + diagnostic.getKind() + n);sb.append(Position: + diagnostic.getPosition() + n);sb.append(Start Position: + diagnostic.getStartPosition() + n);sb.append(End Position: + diagnostic.getEndPosition() + n);sb.append(Source: + diagnostic.getSource() + n);sb.