asm 动态代理的例子，asm动态代理,package org.

asm 动态代理的例子，asm动态代理,package org.

package org.cc.demo2;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import org.objectweb.asm.ClassVisitor;import org.objectweb.asm.ClassWriter;import org.objectweb.asm.FieldVisitor;import org.objectweb.asm.MethodVisitor;import org.objectweb.asm.Opcodes;import org.objectweb.asm.Type;/** *  * <p>根据class A生成一个class B extends A</p> * <li>重写A及A父类的所有方法，eg. public void xx() {super.xx();} * <li>copy A类定义的所有属性 *  * @author dixingxing    * @date May 3, 2012 */public class ClassAdapter extends ClassVisitor implements Opcodes{    public static final String INIT = "<init>";    private ClassWriter classWriter;    private String originalClassName;    private String enhancedClassName;    private Class<?> originalClass;    public ClassAdapter(String enhancedClassName,            Class<?> targetClass, ClassWriter writer) {        super(Opcodes.ASM4,writer);        this.classWriter = writer;        this.originalClassName = targetClass.getName();        this.enhancedClassName = enhancedClassName;        this.originalClass = targetClass;    }    @Override    public void visit(int version, int access, String name, String signature,            String superName, String[] interfaces) {        cv.visit(version, Opcodes.ACC_PUBLIC,                toAsmCls(enhancedClassName), signature, name,                interfaces);    }    @Override    public FieldVisitor visitField(int access, String name, String desc,            String signature, Object value) {        // 拷贝所有属性   可使用java反射给属性赋值（生成class后newInstance在赋值）        return super.visitField(access, name, desc, signature, value);    }    @Override    public MethodVisitor visitMethod(int access, String name, String desc,            String signature, String[] exceptions) {        // 删除所有方法        return null;    }    /**     * 把类名中的.替换为/     * @param className     * @return     */    private static String toAsmCls(String className) {        return className.replace('.', '/');    }    /**     *      * <p>前置方法</p>     *     * @see TxHandler     * @param mWriter     */    private static void doBefore(MethodVisitor mWriter,String methodInfo) {        mWriter.visitFieldInsn(GETSTATIC,"java/lang/System","out","Ljava/io/PrintStream;");          mWriter.visitLdcInsn("before method : " + methodInfo);           mWriter.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println",               "(Ljava/lang/String;)V");           // 或者直接调用静态方法        // mWriter.visitLdcInsn(methodInfo);        // mWriter.visitMethodInsn(INVOKESTATIC,toAsmCls(TxHandler.class.getName()),"before","(Ljava/lang/String;)V");    }    /**     *      * <p>后置方法</p>     * @see TxHandler     * @param mWriter     */    private static void doAfter(MethodVisitor mWriter,String methodInfo) {        mWriter.visitFieldInsn(GETSTATIC,"java/lang/System","out","Ljava/io/PrintStream;");          mWriter.visitLdcInsn("after method : " + methodInfo);           mWriter.visitMethodInsn(INVOKEVIRTUAL, "java/io/PrintStream", "println",               "(Ljava/lang/String;)V");      }    /**     *      * <p>     * object类本身的方法不做重写     * </p>     * <p>     * "main" 方法不做重写     * </p>     *      * @param m     * @return     */    public static boolean needOverride(Method m) {        // object类本身的方法不做重写        if (m.getDeclaringClass().getName().equals(Object.class.getName())) {            return false;        }        // "main" 方法不做重写        if (Modifier.isPublic(m.getModifiers())                && Modifier.isStatic(m.getModifiers())                && m.getReturnType().getName().equals("void")                && m.getName().equals("main")) {            return false;        }        return true;    }    @Override    public void visitEnd() {        // 如果originalClass定义了私有成员变量，那么直接在visitMethod中复制originalClass的<init>会报错。//      ALOAD 0//      INVOKESPECIAL cc/RoleService.<init>()V//      RETURN//      // 调用originalClassName的<init>方法，否则class不能实例化        MethodVisitor mvInit = classWriter.visitMethod(ACC_PUBLIC, INIT, "()V", null, null);         mvInit.visitVarInsn(ALOAD, 0);        mvInit.visitMethodInsn(INVOKESPECIAL, toAsmCls(originalClassName), INIT, "()V");        mvInit.visitInsn(RETURN);        mvInit.visitMaxs(0, 0);        mvInit.visitEnd();         // 获取所有方法，并重写(main方法 和 Object的方法除外)        Method[] methods = originalClass.getMethods();        for(Method m : methods) {            if(!needOverride(m)) {                continue;            }            Type mt = Type.getType(m);            StringBuilder methodInfo = new StringBuilder(originalClassName);            methodInfo.append(".").append(m.getName());            methodInfo.append("|");            Class<?>[] paramTypes = m.getParameterTypes();            for(Class<?> t : paramTypes) {                methodInfo.append(t.getName()).append(",");            }             if(paramTypes.length > 0) {                methodInfo.deleteCharAt(methodInfo.length() - 1);            }            // 方法是被哪个类定义的            String declaringCls = toAsmCls(m.getDeclaringClass().getName());            // 方法 description            MethodVisitor mWriter = classWriter.visitMethod(ACC_PUBLIC, m.getName(), mt.toString(), null, null);             // insert code here (before)            doBefore(mWriter,methodInfo.toString());            int i = 0;            // 如果不是静态方法 load this对象            if(!Modifier.isStatic(m.getModifiers())) {                mWriter.visitVarInsn(ALOAD, i++);            }            StringBuilder sb = new StringBuilder(m.getName());            // load 出方法的所有参数            for(Class<?> tCls : m.getParameterTypes()) {                Type t = Type.getType(tCls);                sb.append(loadCode(t)).append(",");                mWriter.visitVarInsn(loadCode(t), i++);                 if(t.getSort() == Type.LONG || t.getSort() == Type.DOUBLE) {                    i++;                }            }            // super.xxx();            mWriter.visitMethodInsn(INVOKESPECIAL,declaringCls,m.getName(),mt.toString());            // 处理返回值类型            Type rt = Type.getReturnType(m);            // 没有返回值            if(rt.toString().equals("V")) {                doAfter(mWriter,methodInfo.toString());                mWriter.visitInsn(RETURN);            }            // 把return xxx() 转变成 ： Object o = xxx(); return o;            else {                int storeCode = storeCode(rt);                int loadCode = loadCode(rt);                int returnCode = rtCode(rt);                mWriter.visitVarInsn(storeCode, i);                doAfter(mWriter,methodInfo.toString());                mWriter.visitVarInsn(loadCode, i);                mWriter.visitInsn(returnCode);            }            // 已设置了自动计算，但还是要调用一下，不然会报错            mWriter.visitMaxs(i, ++i);            mWriter.visitEnd();         }        cv.visitEnd();    }    /**     *      * <p>get StoreCode(Opcodes#xStore)</p>     *     *     * @param type     * @return     */    public static int storeCode(Type type) {        int sort = type.getSort();        switch (sort) {        case Type.ARRAY:            sort = ASTORE;            break;        case Type.BOOLEAN:            sort = ISTORE;            break;        case Type.BYTE:            sort = ISTORE;            break;        case Type.CHAR:            sort = ISTORE;            break;        case Type.DOUBLE:            sort = DSTORE;            break;        case Type.FLOAT:            sort = FSTORE;            break;        case Type.INT:            sort = ISTORE;            break;        case Type.LONG:            sort = LSTORE;            break;        case Type.OBJECT:            sort = ASTORE;            break;        case Type.SHORT:            sort = ISTORE;            break;        default:            break;        }        return sort;    }    /**     *      *  <p>get StoreCode(Opcodes#xLOAD)</p>     *     * @param type     * @return     */    public static int loadCode(Type type) {        int sort = type.getSort();        switch (sort) {        case Type.ARRAY:            sort = ALOAD;            break;        case Type.BOOLEAN:            sort = ILOAD;            break;        case Type.BYTE:            sort = ILOAD;            break;        case Type.CHAR:            sort = ILOAD;            break;        case Type.DOUBLE:            sort = DLOAD;            break;        case Type.FLOAT:            sort = FLOAD;            break;        case Type.INT:            sort = ILOAD;            break;        case Type.LONG:            sort = LLOAD;            break;        case Type.OBJECT:            sort = ALOAD;            break;        case Type.SHORT:            sort = ILOAD;            break;        default:            break;        }        return sort;    }    /**     *      *  <p>get StoreCode(Opcodes#xRETURN)</p>     *     * @param type     * @return     */    public static int rtCode(Type type) {        int sort = type.getSort();        switch (sort) {        case Type.ARRAY:            sort = ARETURN;            break;        case Type.BOOLEAN:            sort = IRETURN;            break;        case Type.BYTE:            sort = IRETURN;            break;        case Type.CHAR:            sort = IRETURN;            break;        case Type.DOUBLE:            sort = DRETURN;            break;        case Type.FLOAT:            sort = FRETURN;            break;        case Type.INT:            sort = IRETURN;            break;        case Type.LONG:            sort = LRETURN;            break;        case Type.OBJECT:            sort = ARETURN;            break;        case Type.SHORT:            sort = IRETURN;            break;        default:            break;        }        return sort;    }}