java 动态编译.java文件，然后动态加载运行

本文大部分代码，摘自Tomcat6.0源码。

提取Tomcat6.0动态编译java文件核心代码，修整而成。为以后的学习工作带来便利。

编译部分由JDT负责

由URLClassLoader动态加载.class文件后

通过java反射机制运行类

main.java

package com.dynamic;import java.io.File;import java.lang.reflect.Method;import java.net.URL;import java.net.URLClassLoader;import java.util.Arrays;import com.dynamic.compile.DCompile;public class Main {private static String java_file_path = "D:/MyEclipse/DynamicCompile/com/compile/Test.java";private static String java_basic_path = "D:/MyEclipse/DynamicCompile";private static String ecode = "utf8";public void execute() throws Exception{DCompile dc = new DCompile();dc.initialize(java_file_path, java_basic_path, ecode);Class clazz = dc.compile();Object obj = clazz.newInstance();Method method = clazz.getMethod("getName", new Class[]{String.class});String name = (String)method.invoke(obj, "dbdxj");System.out.println(name);}public static void main(String[] args) {Main m = new Main();try{m.execute();}catch(Exception e){e.printStackTrace();}}} 

DCompilationUnit.java

package com.dynamic.compile;import java.io.BufferedReader;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStreamReader;import java.io.Reader;import java.util.StringTokenizer;import org.eclipse.jdt.internal.compiler.env.ICompilationUnit;public class DCompilationUnit implements ICompilationUnit { String className; String sourceFile; String javaEncoding; DCompilationUnit(String sourceFile, String className, String javaEncoding) { this.className = className; this.sourceFile = sourceFile; this.javaEncoding = javaEncoding; } public char[] getFileName() { return sourceFile.toCharArray(); } public char[] getContents() { char[] result = null; FileInputStream is = null; try { is = new FileInputStream(sourceFile); Reader reader = new BufferedReader(new InputStreamReader(is, javaEncoding)); if (reader != null) { char[] chars = new char[8192]; StringBuffer buf = new StringBuffer(); int count; while ((count = reader.read(chars, 0, chars.length)) > 0) { buf.append(chars, 0, count); } result = new char[buf.length()]; buf.getChars(0, result.length, result, 0); } } catch (IOException e) { e.printStackTrace(); } finally { if (is != null) { try { is.close(); } catch (IOException exc) { // Ignore } } } return result; } public char[] getMainTypeName() { int dot = className.lastIndexOf('.'); if (dot > 0) { return className.substring(dot + 1).toCharArray(); } return className.toCharArray(); } public char[][] getPackageName() { StringTokenizer izer = new StringTokenizer(className, "."); char[][] result = new char[izer.countTokens()-1][]; for (int i = 0; i < result.length; i++) { String tok = izer.nextToken(); result[i] = tok.toCharArray(); } return result; }}

DCompile.java

package com.dynamic.compile;import java.io.File;import java.net.URL;import java.net.URLClassLoader;import java.util.Locale;import java.util.Map;import java.util.HashMap;import org.eclipse.jdt.internal.compiler.Compiler;import org.eclipse.jdt.internal.compiler.DefaultErrorHandlingPolicies;import org.eclipse.jdt.internal.compiler.IErrorHandlingPolicy;import org.eclipse.jdt.internal.compiler.IProblemFactory;import org.eclipse.jdt.internal.compiler.env.ICompilationUnit;import org.eclipse.jdt.internal.compiler.impl.CompilerOptions;import org.eclipse.jdt.internal.compiler.problem.DefaultProblemFactory;public class DCompile {private String java_file_path;private String java_basic_path;private String ecode;private Boolean init = false;private ICompilationUnit[] compilationUnits = null;public Class compile() throws Exception {if (!check()) {throw new Exception("Not initialize...");}Class clazz = null;String targetClassName = getTargetClassName();final DNameEnvironment env = new DNameEnvironment(targetClassName,java_file_path, Thread.currentThread().getContextClassLoader(),ecode);final IErrorHandlingPolicy policy = DefaultErrorHandlingPolicies.proceedWithAllProblems();final DCompilerRequestor requestor = new DCompilerRequestor(java_basic_path);final IProblemFactory problemFactory = new DefaultProblemFactory(Locale.getDefault());Compiler compiler = new Compiler(env, policy, getSettings(), requestor,problemFactory, true);compiler.compile(compilationUnits);URL url = new URL("file:/" + java_basic_path + "/");System.out.println(url);URLClassLoader ucl = new URLClassLoader(new URL[]{url});clazz = ucl.loadClass(targetClassName);return clazz;}public Map getSettings() {Map settings = new HashMap();settings.put(CompilerOptions.OPTION_LineNumberAttribute,CompilerOptions.GENERATE);settings.put(CompilerOptions.OPTION_SourceFileAttribute,CompilerOptions.GENERATE);settings.put(CompilerOptions.OPTION_ReportDeprecation,CompilerOptions.IGNORE);settings.put(CompilerOptions.OPTION_Encoding, ecode);// Source JVMsettings.put(CompilerOptions.OPTION_Source, CompilerOptions.VERSION_1_6);// Target JVMsettings.put(CompilerOptions.OPTION_TargetPlatform,CompilerOptions.VERSION_1_6);settings.put(CompilerOptions.OPTION_Compliance,CompilerOptions.VERSION_1_6);return settings;}private boolean check() {return init;}public DCompile() {}public String getTargetClassName() {String targetClassName = java_file_path.substring(java_basic_path.length() + 1, java_file_path.indexOf("."));return targetClassName.replace("/", ".");}public void initialize(String file_path, String basic_path, String ecode) {this.java_file_path = file_path;this.java_basic_path = basic_path;this.ecode = ecode;String targetClassName = getTargetClassName();if (targetClassName == null) {targetClassName = "";}compilationUnits = new ICompilationUnit[1];compilationUnits[0] = new DCompilationUnit(this.java_file_path, targetClassName,this.ecode);init = true;}}

DCompilerRequestor.java

package com.dynamic.compile;import java.io.BufferedOutputStream;import java.io.FileOutputStream;import java.io.IOException;import org.eclipse.jdt.core.compiler.IProblem;import org.eclipse.jdt.internal.compiler.ClassFile;import org.eclipse.jdt.internal.compiler.CompilationResult;import org.eclipse.jdt.internal.compiler.ICompilerRequestor;public class DCompilerRequestor implements ICompilerRequestor{private String outputDir;public DCompilerRequestor(String outDir){this.outputDir = outDir;} public void acceptResult(CompilationResult result) { try { boolean error = false; if (result.hasProblems()) { IProblem[] problems = result.getProblems(); for (int i = 0; i < problems.length; i++) { IProblem problem = problems[i]; if (problem.isError()) { error = true; System.err.println(problem.toString()); } } } if (!error) { ClassFile[] classFiles = result.getClassFiles(); for (int i = 0; i < classFiles.length; i++) { ClassFile classFile = classFiles[i]; char[][] compoundName = classFile.getCompoundName(); String className = ""; String sep = ""; for (int j = 0; j < compoundName.length; j++) { className += sep; className += new String(compoundName[j]); sep = "."; } byte[] bytes = classFile.getBytes(); String outFile = outputDir + "/" + className.replace('.', '/') + ".class"; FileOutputStream fout = new FileOutputStream(outFile); BufferedOutputStream bos = new BufferedOutputStream(fout); bos.write(bytes); bos.close(); } } } catch (IOException exc) { exc.printStackTrace(); } }}

DNameEnvironment.java

package com.dynamic.compile;import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.InputStream;import org.eclipse.jdt.internal.compiler.classfmt.ClassFileReader;import org.eclipse.jdt.internal.compiler.env.ICompilationUnit;import org.eclipse.jdt.internal.compiler.env.INameEnvironment;import org.eclipse.jdt.internal.compiler.env.NameEnvironmentAnswer;public class DNameEnvironment implements INameEnvironment {private String targetClassName;private String sourceFile;private ClassLoader classLoader;private String encode;public DNameEnvironment(String targetClassName, String sourceFile, ClassLoader classLoader, String encode){this.targetClassName = targetClassName;this.sourceFile = sourceFile;this.classLoader = classLoader;this.encode = encode;}public NameEnvironmentAnswer findType(char[][] compoundTypeName) {String result = "";String sep = "";for (int i = 0; i < compoundTypeName.length; i++) {result += sep;result += new String(compoundTypeName[i]);sep = ".";}return findType(result);}public NameEnvironmentAnswer findType(char[] typeName, char[][] packageName) {String result = "";String sep = "";for (int i = 0; i < packageName.length; i++) {result += sep;result += new String(packageName[i]);sep = ".";}result += sep;result += new String(typeName);return findType(result);}private NameEnvironmentAnswer findType(String className) {InputStream is = null;try {if (className.equals(targetClassName)) {ICompilationUnit compilationUnit = new DCompilationUnit(sourceFile, className, encode);return new NameEnvironmentAnswer(compilationUnit, null);}String resourceName = className.replace('.', '/') + ".class";is = classLoader.getResourceAsStream(resourceName);if (is != null) {byte[] classBytes;byte[] buf = new byte[8192];ByteArrayOutputStream baos = new ByteArrayOutputStream(buf.length);int count;while ((count = is.read(buf, 0, buf.length)) > 0) {baos.write(buf, 0, count);}baos.flush();classBytes = baos.toByteArray();char[] fileName = className.toCharArray();ClassFileReader classFileReader = new ClassFileReader(classBytes, fileName, true);return new NameEnvironmentAnswer(classFileReader, null);}} catch (IOException exc) {exc.printStackTrace();} catch (org.eclipse.jdt.internal.compiler.classfmt.ClassFormatException exc) {exc.printStackTrace();} finally {if (is != null) {try {is.close();} catch (IOException exc) {// Ignore}}}return null;}private boolean isPackage(String result) {if (result.equals(targetClassName)) {return false;}String resourceName = result.replace('.', '/') + ".class";InputStream is = classLoader.getResourceAsStream(resourceName);return is == null;}public boolean isPackage(char[][] parentPackageName, char[] packageName) {String result = "";String sep = "";if (parentPackageName != null) {for (int i = 0; i < parentPackageName.length; i++) {result += sep;String str = new String(parentPackageName[i]);result += str;sep = ".";}}String str = new String(packageName);if (Character.isUpperCase(str.charAt(0))) {if (!isPackage(result)) {return false;}}result += sep;result += str;return isPackage(result);}public void cleanup() {}}

Test.java

package com.compile;public class Test{public Test(){System.out.println("initialize... Test.class");}public String getName(String name){return ("孙子你成功了:" + name);}}

动态编译后.class文件自动生成

WindowsXP  JDK6 测试通过

Console:

file:/D:/MyEclipse/DynamicCompile/
initialize... Test.class
孙子你成功了:dbdxj

 

 

这只是简单的提取，详细的学习待续。。。

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最新文件 更新时间:2010,04,15

更新内容包括引用外部文件，引用外部jar包，引用当前程序文件等。

http://download.csdn.net/source/2244811