utility code that generates wrapper subtypes.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@35984 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/util/SubClassGenerator.java

+/*
+ * The MIT License
+ *
+ * Copyright (c) 2010, InfraDNA, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package hudson.util;
+
+import org.objectweb.asm.ClassWriter;
+import org.objectweb.asm.MethodVisitor;
+import org.objectweb.asm.Type;
+
+import java.lang.reflect.Constructor;
+
+import static org.objectweb.asm.Opcodes.*;
+
+/**
+ * Generates a new class that just defines constructors into the super types.
+ *
+ * @author Kohsuke Kawaguchi
+ */
+public class SubClassGenerator extends ClassLoader {
+    public SubClassGenerator(ClassLoader parent) {
+        super(parent);
+    }
+
+    public <T> Class<? extends T> generate(Class<T> base, String name) {
+        ClassWriter cw = new ClassWriter(false,false);//?
+        cw.visit(49, ACC_PUBLIC, name, null,
+                Type.getInternalName(base),null);
+
+        for (Constructor c : base.getDeclaredConstructors()) {
+            Class[] et = c.getExceptionTypes();
+            String[] exceptions = new String[et.length];
+            for (int i = 0; i < et.length; i++)
+                exceptions[i] = Type.getInternalName(et[i]);
+
+            String methodDescriptor = getMethodDescriptor(c);
+            MethodVisitor m = cw.visitMethod(c.getModifiers(), "<init>", methodDescriptor, null, exceptions);
+            m.visitCode();
+
+            int index=1;
+            m.visitVarInsn(ALOAD,0);
+            for (Class param : c.getParameterTypes()) {
+                Type t = Type.getType(param);
+                m.visitVarInsn(t.getOpcode(ILOAD), index);
+                index += t.getSize();
+            }
+            m.visitMethodInsn(INVOKESPECIAL, Type.getInternalName(base), "<init>", methodDescriptor);
+            m.visitInsn(RETURN);
+            m.visitMaxs(index,index);
+            m.visitEnd();
+        }
+
+        cw.visitEnd();
+        byte[] image = cw.toByteArray();
+
+        return defineClass(name, image, 0, image.length).asSubclass(base);
+    }
+
+    private String getMethodDescriptor(Constructor c) {
+        StringBuilder buf = new StringBuilder();
+        buf.append('(');
+        for (Class p : c.getParameterTypes())
+            buf.append(Type.getDescriptor(p));
+
+        buf.append(")V");
+        return buf.toString();
+    }
+}

core/src/test/java/hudson/util/SubClassGeneratorTest.java

+/*
+ * The MIT License
+ *
+ * Copyright (c) 2010, InfraDNA, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package hudson.util;
+
+import junit.framework.TestCase;
+
+/**
+ * 
+ * @author Kohsuke Kawaguchi
+ */
+public class SubClassGeneratorTest extends TestCase {
+    public static class Foo {
+        String s;
+        double x;
+        int y;
+        public Foo() {}
+        public Foo(String s) {this.s=s;}
+        public Foo(double x, int y) {this.x=x;this.y=y;}
+    }
+    public void testFoo() throws Exception {
+        Class<? extends Foo> c = new SubClassGenerator(getClass().getClassLoader()).generate(Foo.class, "12345");
+        assertEquals("12345",c.getName());
+
+        c.newInstance();
+
+        Foo f = c.getConstructor(String.class).newInstance("aaa");
+        assertEquals("aaa",f.s);
+
+        f = c.getConstructor(double.class,int.class).newInstance(1.0,3);
+        assertEquals(1.0,f.x);
+        assertEquals(3,f.y);
+    }
+}