first commit

Author: trung

.gitignore

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+.idea
+InMemoryJavaCompiler.iml

pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>org.mdkt.compiler</groupId>
+    <artifactId>InMemoryJavaCompiler</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+
+    <name>InMemoryJavaCompiler</name>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

src/main/java/org/mdkt/compiler/CompiledCode.java

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+package org.mdkt.compiler;
+
+import javax.tools.SimpleJavaFileObject;
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.net.URI;
+
+/**
+ * Created by trung on 5/3/15.
+ */
+public class CompiledCode extends SimpleJavaFileObject {
+    private ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+    public CompiledCode(String className) throws Exception {
+        super(new URI(className), Kind.CLASS);
+    }
+
+    @Override
+    public OutputStream openOutputStream() throws IOException {
+        return baos;
+    }
+
+    public byte[] getByteCode() {
+        return baos.toByteArray();
+    }
+}

src/main/java/org/mdkt/compiler/DynamicClassLoader.java

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+package org.mdkt.compiler;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Created by trung on 5/3/15.
+ */
+public class DynamicClassLoader extends ClassLoader {
+
+    private Map<String, CompiledCode> customCompiledCode = new HashMap<>();
+
+    public DynamicClassLoader(ClassLoader parent) {
+        super(parent);
+    }
+
+    public void setCode(CompiledCode cc) {
+        customCompiledCode.put(cc.getName(), cc);
+    }
+
+    @Override
+    protected Class<?> findClass(String name) throws ClassNotFoundException {
+        CompiledCode cc = customCompiledCode.get(name);
+        if (cc == null) {
+            return super.findClass(name);
+        }
+        byte[] byteCode = cc.getByteCode();
+        return defineClass(name, byteCode, 0, byteCode.length);
+    }
+}

src/main/java/org/mdkt/compiler/ExtendedStandardJavaFileManager.java

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+package org.mdkt.compiler;
+
+import javax.tools.FileObject;
+import javax.tools.ForwardingJavaFileManager;
+import javax.tools.JavaFileManager;
+import javax.tools.JavaFileObject;
+import java.io.IOException;
+
+/**
+ * Created by trung on 5/3/15.
+ */
+public class ExtendedStandardJavaFileManager extends ForwardingJavaFileManager<JavaFileManager> {
+
+    private CompiledCode compiledCode;
+    private DynamicClassLoader cl;
+
+    /**
+     * Creates a new instance of ForwardingJavaFileManager.
+     *
+     * @param fileManager delegate to this file manager
+     * @param cl
+     */
+    protected ExtendedStandardJavaFileManager(JavaFileManager fileManager, CompiledCode compiledCode, DynamicClassLoader cl) {
+        super(fileManager);
+        this.compiledCode = compiledCode;
+        this.cl = cl;
+        this.cl.setCode(compiledCode);
+    }
+
+    @Override
+    public JavaFileObject getJavaFileForOutput(JavaFileManager.Location location, String className, JavaFileObject.Kind kind, FileObject sibling) throws IOException {
+        return compiledCode;
+    }
+
+    @Override
+    public ClassLoader getClassLoader(JavaFileManager.Location location) {
+        return cl;
+    }
+}

src/main/java/org/mdkt/compiler/InMemoryJavaCompiler.java

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+package org.mdkt.compiler;
+
+import javax.tools.JavaCompiler;
+import javax.tools.JavaFileObject;
+import javax.tools.ToolProvider;
+import java.util.Arrays;
+
+/**
+ * Created by trung on 5/3/15.
+ */
+public class InMemoryJavaCompiler {
+    static JavaCompiler javac = ToolProvider.getSystemJavaCompiler();
+
+    public static Class<?> compile(String className, String sourceCodeInText) throws Exception {
+        SourceCode sourceCode = new SourceCode(className, sourceCodeInText);
+        CompiledCode compiledCode = new CompiledCode(className);
+        Iterable<? extends JavaFileObject> compilationUnits = Arrays.asList(sourceCode);
+        DynamicClassLoader cl = new DynamicClassLoader(ClassLoader.getSystemClassLoader());
+        ExtendedStandardJavaFileManager fileManager = new ExtendedStandardJavaFileManager(javac.getStandardFileManager(null, null, null), compiledCode, cl);
+        JavaCompiler.CompilationTask task = javac.getTask(null, fileManager, null, null, null, compilationUnits);
+        boolean result = task.call();
+        return cl.loadClass(className);
+    }
+}

src/main/java/org/mdkt/compiler/SourceCode.java

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+package org.mdkt.compiler;
+
+import javax.tools.SimpleJavaFileObject;
+import java.io.IOException;
+import java.net.URI;
+
+/**
+ * Created by trung on 5/3/15.
+ */
+public class SourceCode extends SimpleJavaFileObject {
+    private String contents = null;
+
+    public SourceCode(String className, String contents) throws Exception {
+        super(URI.create("string:///" + className.replace('.', '/') + Kind.SOURCE.extension), Kind.SOURCE);
+        this.contents = contents;
+    }
+
+    public CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException {
+        return contents;
+    }
+}

src/test/java/org/mdkt/compiler/InMemoryJavaCompilerTest.java

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+package org.mdkt.compiler;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * Created by trung on 5/3/15.
+ */
+public class InMemoryJavaCompilerTest {
+
+    @Test
+    public void compile_whenTypical() throws Exception {
+        StringBuffer sourceCode = new StringBuffer();
+
+        sourceCode.append("package org.mdkt;\n");
+        sourceCode.append("public class HelloClass {\n");
+        sourceCode.append("   public String hello() { return \"hello\"; }");
+        sourceCode.append("}");
+
+        Class<?> helloClass = InMemoryJavaCompiler.compile("org.mdkt.HelloClass", sourceCode.toString());
+        Assert.assertNotNull(helloClass);
+        Assert.assertEquals(1, helloClass.getDeclaredMethods().length);
+    }
+}