不用其他jar包，获取随机排列数组。

/*
* 网上看到一道题，挺有意思。记录下来。
*/

package array;


public class RandomArray<T> {
	
	private T[] array;
	
	private Object[] result;
	
	private Integer count = 0;
	
	private T[] getArray() {
		return array;
	}

	private void setArray(T[] array) {
		this.array = array;
		Integer size = 1;
		for (Integer i = array.length; i >= 1; i --) {
			size *= i;
		}
		System.out.println("result size = " + size);
		this.result = new Object[size];
	}
	
	private Object[] getResult() {
		return result;
	} 
	
	private void putElementToResult(T[] array) {
		result[count] = array;
	}
	
	private RandomArray (T[] array) {
		this.setArray(array);
	}

	private void exchange (Integer originalIndex, Integer destinationIndex) {
		if (originalIndex.compareTo(destinationIndex) == 0) { 
			return;
		}
		T[] array = this.getArray();
		T temp = array[originalIndex];
		array[originalIndex] = array[destinationIndex];
		array[destinationIndex] = temp;
	}
	
	private Object[] copyArray(T[] array) {
		Object[] objs = new Object[array.length];
		for (Integer i = 0; i < array.length; i++) {
			objs[i] = array[i];
		}
		return objs;
	}
	
	private void arrayHandler (Integer startIndex, Integer endIndex) {
		if (startIndex.compareTo(endIndex) != 0) {
			for(Integer i = startIndex; i <= endIndex; i ++ ) {
				exchange(startIndex, i);
				arrayHandler(startIndex + 1, endIndex);
				exchange(i, startIndex);
			}
		} else {
			@SuppressWarnings("unchecked")
			T[] param = (T[]) copyArray(array);
			this.putElementToResult(param);
			this.count ++;
		}
	}
	
	private Integer getRandomNumber() {
		Integer countLength = count.toString().length();
		while(true) {
			Long currentMillis = System.currentTimeMillis();
			String compareVal = currentMillis.toString().substring(currentMillis.toString().length() - countLength);
			Integer number = getValidNumber(compareVal);
			if (number <= count) {
				return number;
			}
		}
	}
	
	private Integer getValidNumber(String compareVal) {
		if ("0".equals(compareVal)) {
			return 0;
		} else if(compareVal.startsWith("0")) {
			compareVal = compareVal.replaceFirst("0", "");
			return getValidNumber(compareVal);
		} else {
			return Integer.valueOf(compareVal);
		}
	}
	
	@SuppressWarnings("unchecked")
	private T[] convertObjectArrayToGenericArray(Object[] data, T[] container) {
		for(Integer i = 0; i < data.length; i ++) {
			container[i] = (T) data[i];
		}
		return container;
	}
	
	public T[] getRandomArray(T[] container) {
		arrayHandler(0,this.getArray().length - 1);
		Object[] _this = this.getResult();
		Integer indexNumber = getRandomNumber();
		Object[] objs = (Object[]) _this[indexNumber];
		return convertObjectArrayToGenericArray(objs, container);
	}
	public static void main(String[] args) {
                /*
                 *test
                 */
		String[] array = {"1","2","3"};
		RandomArray<String> ran = new RandomArray<String>(array);
		String[] randomArray = ran.getRandomArray(new String[3]);
		for (String str: randomArray) {
			System.out.print(str + " ");
		}
	}
}