java反射：使用asm 获取方法的参数名

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[Java]代码
/** * Classes.java 9:22:44 AM Apr 23, 2012 * * Copyright(c) 2000-2012 HC360.COM, All Rights Reserved. */package cn.outofmemory.demo;import java.io.IOException;import java.lang.reflect.Method;import java.lang.reflect.Modifier;import java.util.Arrays;import org.objectweb.asm.ClassReader;import org.objectweb.asm.ClassVisitor;import org.objectweb.asm.Label;import org.objectweb.asm.MethodVisitor;import org.objectweb.asm.Opcodes;import org.objectweb.asm.Type;/** * <p> * 基于asm的工具类 * </p> *  * @author dixingxing * @date Apr 23, 2012 */public final class Classes {    private Classes() {    }    /**     *      * <p>     * 比较参数类型是否一致     * </p>     *      * @param types     *            asm的类型({@link Type})     * @param clazzes     *            java 类型({@link Class})     * @return     */    private static boolean sameType(Type[] types, Class<?>[] clazzes) {        // 个数不同        if (types.length != clazzes.length) {            return false;        }        for (int i = 0; i < types.length; i++) {            if (!Type.getType(clazzes[i]).equals(types[i])) {                return false;            }        }        return true;    }    /**     *      * <p>     * 获取方法的参数名     * </p>     *      * @param m     * @return     */    public static String[] getMethodParamNames(final Method m) {        final String[] paramNames = new String[m.getParameterTypes().length];        final String n = m.getDeclaringClass().getName();        ClassReader cr = null;        try {            cr = new ClassReader(n);        } catch (IOException e) {            throw new RuntimeException(e);        }        cr.accept(new ClassVisitor(Opcodes.ASM4) {            @Override            public MethodVisitor visitMethod(final int access,                    final String name, final String desc,                    final String signature, final String[] exceptions) {                final Type[] args = Type.getArgumentTypes(desc);                // 方法名相同并且参数个数相同                if (!name.equals(m.getName())                        || !sameType(args, m.getParameterTypes())) {                    return super.visitMethod(access, name, desc, signature,                            exceptions);                }                MethodVisitor v = super.visitMethod(access, name, desc,                        signature, exceptions);                return new MethodVisitor(Opcodes.ASM4, v) {                    @Override                    public void visitLocalVariable(String name, String desc,                            String signature, Label start, Label end, int index) {                        int i = index - 1;                        // 如果是静态方法，则第一就是参数                        // 如果不是静态方法，则第一个是"this"，然后才是方法的参数                        if (Modifier.isStatic(m.getModifiers())) {                            i = index;                        }                        if (i >= 0 && i < paramNames.length) {                            paramNames[i] = name;                        }                        super.visitLocalVariable(name, desc, signature, start,                                end, index);                    }                };            }        }, 0);        return paramNames;    }    public static void main(String[] args) throws SecurityException,            NoSuchMethodException {        String[] s = getMethodParamNames(Classes.class.getMethod(                "getMethodParamNames", Method.class));        System.out.println(Arrays.toString(s));        s = getMethodParamNames(Classes.class.getDeclaredMethod("sameType",                Type[].class, Class[].class));        System.out.println(Arrays.toString(s));        s = getMethodParamNames(MethodVisitor.class.getDeclaredMethod("visitAnnotation",                String.class,Boolean.TYPE));        System.out.println(Arrays.toString(s));        // 对String，Object，thread等jdk自带类型不起作用    }}
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