获得方法形参名称列表By ASM (Java)

MethodParamNamesScanerByASM.java

package com.weirhp;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.tree.ClassNode;
import org.objectweb.asm.tree.LocalVariableNode;
import org.objectweb.asm.tree.MethodNode;
/**
 * 通过读取Class文件,获得方法形参名称列表
 * 
 * @author weirhp(weirhp@gmail.com)
 * 修改自wendal的https://gist.github.com/2011728
 */
public class MethodParamNamesScanerByASM {
    public static void main(String[] args) throws IOException {
        Map<String, List<String>> map = getParamNames(new FileInputStream(
                "D:\\project\\dodopipe.ui.osgi.example.service\\target\\classes\\dodopipe\\ui\\osgi\\example\\service\\impl\\RedmineServiceImpl.class"));
        for (String key : map.keySet()) {
            System.out.println(key);
            System.out.print("\t");
            for (String str : map.get(key)) {
                System.out.print(str + "|");
            }
            System.out.println();
        }
    }

    /**
     * 获取Method的形参名称列表
     * 
     * @param method
     *            需要解析的方法
     * @return 形参名称列表,如果没有调试信息,将返回null
     */
    public static List<String> getParamNames(Method method) {
        try {
            int size = method.getParameterTypes().length;
            if (size == 0)
                return new ArrayList<String>(0);
            List<String> list = getParamNames(method.getDeclaringClass()).get(
                    getKey(method));
            if (list != null && list.size() != size)
                return list.subList(0, size);
            return list;
        } catch (Throwable e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 获取一个类的所有方法/构造方法的形参名称Map
     * 
     * @param klass
     *            需要解析的类
     * @return 所有方法/构造方法的形参名称Map
     * @throws IOException
     *             如果有任何IO异常,不应该有,如果是本地文件,那100%遇到bug了
     */
    public static Map<String, List<String>> getParamNames(Class<?> klass)
            throws IOException {
        InputStream in = klass.getResourceAsStream("/"
                + klass.getName().replace('.', '/') + ".class");
        return getParamNames(in);
    }

    public static Map<String, List<String>> getParamNames(InputStream in)
            throws IOException {
        ClassReader cr = new ClassReader(in);
        ClassNode cn = new ClassNode();
        cr.accept(cn, ClassReader.EXPAND_FRAMES);
        List<MethodNode> methods = cn.methods;
        Map<String, List<String>> rtn = new HashMap<String, List<String>>();
        for (int i = 0; i < methods.size(); ++i) {
            List<LocalVariable> varNames = new ArrayList<LocalVariable>();
            MethodNode method = methods.get(i);
            List<LocalVariableNode> local_variables = method.localVariables;
            for (int l = 0; l < local_variables.size(); l++) {
                String varName = local_variables.get(l).name;
                // index
                int index = local_variables.get(l).index;
                if (!"this".equals(varName)) // 非静态方法,第一个参数是this
                    varNames.add(new LocalVariable(index, varName));
            }
            LocalVariable[] tmpArr = varNames.toArray(new LocalVariable[0]);
            Arrays.sort(tmpArr);
            List<String> list = new ArrayList<String>();
            for (LocalVariable var : tmpArr) {
                list.add(var.name);
            }
            rtn.put(method.name + "," + method.desc, list);
        }
        return rtn;
    }

    static class LocalVariable implements Comparable<LocalVariable> {
        public int    index;
        public String name;

        public LocalVariable(int index, String name) {
            this.index = index;
            this.name = name;
        }

        public int compareTo(LocalVariable o) {
            return this.index - o.index;
        }
    }

    /**
     * 获取Constructor的形参名称列表
     * 
     * @param constructor
     *            需要解析的构造函数
     * @return 形参名称列表,如果没有调试信息,将返回null
     */
    public static List<String> getParamNames(Constructor<?> constructor) {
        try {
            int size = constructor.getParameterTypes().length;
            if (size == 0)
                return new ArrayList<String>(0);
            List<String> list = getParamNames(constructor.getDeclaringClass())
                    .get(getKey(constructor));
            if (list != null && list.size() != size)
                return list.subList(0, size);
            return list;
        } catch (Throwable e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * 传入Method或Constructor,获取getParamNames方法返回的Map所对应的key
     */
    public static String getKey(Object obj) {
        StringBuilder sb = new StringBuilder();
        if (obj instanceof Method) {
            sb.append(((Method) obj).getName()).append(',');
            getDescriptor(sb, (Method) obj);
        } else if (obj instanceof Constructor) {
            sb.append("<init>,"); // 只有非静态构造方法才能用有方法参数的,而且通过反射API拿不到静态构造方法
            getDescriptor(sb, (Constructor<?>) obj);
        } else
            throw new RuntimeException("Not Method or Constructor!");
        return sb.toString();
    }

    public static void getDescriptor(StringBuilder sb, Method method) {
        sb.append('(');
        for (Class<?> klass : method.getParameterTypes())
            getDescriptor(sb, klass);
        sb.append(')');
        getDescriptor(sb, method.getReturnType());
    }

    public static void getDescriptor(StringBuilder sb,
            Constructor<?> constructor) {
        sb.append('(');
        for (Class<?> klass : constructor.getParameterTypes())
            getDescriptor(sb, klass);
        sb.append(')');
        sb.append('V');
    }

    /** 本方法来源于ow2的asm库的Type类 */
    public static void getDescriptor(final StringBuilder buf, final Class<?> c) {
        Class<?> d = c;
        while (true) {
            if (d.isPrimitive()) {
                char car;
                if (d == Integer.TYPE) {
                    car = 'I';
                } else if (d == Void.TYPE) {
                    car = 'V';
                } else if (d == Boolean.TYPE) {
                    car = 'Z';
                } else if (d == Byte.TYPE) {
                    car = 'B';
                } else if (d == Character.TYPE) {
                    car = 'C';
                } else if (d == Short.TYPE) {
                    car = 'S';
                } else if (d == Double.TYPE) {
                    car = 'D';
                } else if (d == Float.TYPE) {
                    car = 'F';
                } else /* if (d == Long.TYPE) */{
                    car = 'J';
                }
                buf.append(car);
                return;
            } else if (d.isArray()) {
                buf.append('[');
                d = d.getComponentType();
            } else {
                buf.append('L');
                String name = d.getName();
                int len = name.length();
                for (int i = 0; i < len; ++i) {
                    char car = name.charAt(i);
                    buf.append(car == '.' ? '/' : car);
                }
                buf.append(';');
                return;
            }
        }
    }
}