Returns the descriptor for the passed member - Java Reflection

Java examples for Reflection:Method Return

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Description

Returns the descriptor for the passed member

Demo Code

//package com.java2s;

import java.lang.reflect.Constructor;
import java.lang.reflect.Member;
import java.lang.reflect.Method;

public class Main {
    /**//from   w  w  w  .ja v a2 s .c  o  m
     * Returns the descriptor for the passed member
     * @param m The class member
     * @return the member descriptor
     */
    public static String getMemberDescriptor(final Member m) {
        if (m instanceof Method) {
            return getMethodDescriptor((Method) m);
        } else if (m instanceof Constructor) {
            return getConstructorDescriptor((Constructor) m);
        } else {
            return m.toString();
        }
    }

    /**
     * Returns the descriptor corresponding to the given method.
     * @param m a {@link Method Method} object.
     * @return the descriptor of the given method.
     * (All credit to ObjectWeb ASM)
     * @author Eric Bruneton  
     * @author Chris Nokleberg
     */
    public static String getMethodDescriptor(final Method m) {
        Class<?>[] parameters = m.getParameterTypes();
        StringBuffer buf = new StringBuffer();
        buf.append('(');
        for (int i = 0; i < parameters.length; ++i) {
            getDescriptor(buf, parameters[i]);
        }
        buf.append(')');
        getDescriptor(buf, m.getReturnType());
        return buf.toString();
    }

    /**
     * Returns the descriptor corresponding to the given constructor.
     * @param c a {@link Constructor Constructor} object.
     * @return the descriptor of the given constructor.
     * (All credit to ObjectWeb ASM)
     * @author Eric Bruneton  
     * @author Chris Nokleberg
     */
    public static String getConstructorDescriptor(final Constructor<?> c) {
        Class<?>[] parameters = c.getParameterTypes();
        StringBuffer buf = new StringBuffer();
        buf.append('(');
        for (int i = 0; i < parameters.length; ++i) {
            getDescriptor(buf, parameters[i]);
        }
        return buf.append(")V").toString();
    }

    /**
     * Appends the descriptor of the given class to the given string buffer.
     * @param buf the string buffer to which the descriptor must be appended.
     * @param c the class whose descriptor must be computed.
     * (All credit to ObjectWeb ASM)
     * @author Eric Bruneton  
     * @author Chris Nokleberg
     */
    private static void getDescriptor(final StringBuffer 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;
            }
        }
    }
}

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