javamock生成对象

`import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Random;

public class Mock {

private static final Boolean[] bools                 = new Boolean[] { true, false };

private static final char[]    words                 = new char[] { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i',
        'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z' };

private static final Random    r                     = new Random();

private static final int       MAX_COLLECTION_LENGTH = 50;

private static final int       MAX_STRING_LENGTH     = 30;

@SuppressWarnings({ "unchecked", "rawtypes" })
public static <T> T mock(Class<T> clazz) {
    if (clazz == Character.class || clazz == Character.TYPE) {
        return (T) (Character) words[r.nextInt(words.length)];
    } else if (clazz == Boolean.class || clazz == Boolean.TYPE) {
        return (T) (Boolean) bools[r.nextInt(bools.length)];
    } else if (clazz == Long.class || clazz == Long.TYPE) {
        return (T) (Long) r.nextLong();
    } else if (clazz == Integer.class || clazz == Integer.TYPE) {
        return (T) (Integer) r.nextInt();
    } else if (clazz == Short.class || clazz == Short.TYPE) {
        return (T) (Short) new Integer(r.nextInt(127)).shortValue();
    } else if (clazz == Float.class || clazz == Float.TYPE) {
        return (T) (Float) r.nextFloat();
    } else if (clazz == Double.class || clazz == Double.TYPE) {
        return (T) (Double) r.nextDouble();
    } else if (clazz == String.class) {
        return (T) randString(r.nextInt(MAX_STRING_LENGTH));
    }

    try {
        T instance = clazz.newInstance();

        for (Field f : ReflectUtil.getFields(clazz)) {
            f.setAccessible(true);
            Length lengthAnno = f.getAnnotation(Length.class);

            if (f.getType() == Character.TYPE) {
                f.setChar(instance, words[r.nextInt(words.length)]);
            } else if (f.getType() == Character.class) {
                f.set(instance, words[r.nextInt(words.length)]);
            } else if (f.getType() == Boolean.TYPE) {
                f.setBoolean(instance, bools[r.nextInt(bools.length)]);
            } else if (f.getType() == Boolean.class) {
                f.set(instance, bools[r.nextInt(bools.length)]);
            } else if (f.getType() == Long.TYPE) {
                f.setLong(instance, r.nextLong());
            } else if (f.getType() == Long.class) {
                f.set(instance, r.nextLong());
            } else if (f.getType() == Integer.TYPE) {
                f.setInt(instance, r.nextInt());
            } else if (f.getType() == Integer.class) {
                f.set(instance, r.nextInt());
            } else if (f.getType() == Short.TYPE) {
                f.setShort(instance, new Integer(r.nextInt(127)).shortValue());
            } else if (f.getType() == Short.class) {
                f.set(instance, new Integer(r.nextInt(127)).shortValue());
            } else if (f.getType() == Float.TYPE) {
                f.setFloat(instance, r.nextFloat());
            } else if (f.getType() == Float.class) {
                f.set(instance, r.nextFloat());
            } else if (f.getType() == Double.TYPE) {
                f.setDouble(instance, r.nextDouble());
            } else if (f.getType() == Double.class) {
                f.set(instance, r.nextDouble());
            } else if (f.getType() == String.class) {
                f.set(instance, randString(r.nextInt(MAX_STRING_LENGTH)));
            } else if (f.getType() == List.class) {
                int size = r.nextInt(MAX_COLLECTION_LENGTH);
                List<Object> list = new ArrayList<Object>(size);
                ParameterizedType pt = null;
                for (int i = 0; i < size; i++) {
                    pt = (ParameterizedType) f.getGenericType();
                    list.add(mock((Class) pt.getActualTypeArguments()[0]));
                }
                f.set(instance, list);
            } else if (f.getType() == Map.class) {
                int size = r.nextInt(MAX_COLLECTION_LENGTH);
                Map<Object, Object> map = new HashMap<Object, Object>();
                ParameterizedType pt = null;
                for (int i = 0; i < size; i++) {
                    pt = (ParameterizedType) f.getGenericType();
                    map.put(mock((Class) pt.getActualTypeArguments()[0]),
                            mock((Class) pt.getActualTypeArguments()[1]));
                }
                f.set(instance, map);
            } else if (f.getType() == Date.class) {
                f.set(instance, new Date());
            } else {
                f.set(instance, mock(f.getType()));
            }
        }

        return instance;
    } catch (Exception e) {
        throw new IllegalArgumentException(e);
    }
}

private static String randString(int count) {
    if (count == 0) {
        count = 1;
    }

    int length = words.length;
    char[] text = new char[count];
    for (int i = 0; i < count; i++) {
        text[i] = words[r.nextInt(length)];
    }

    return new String(text);
}

}