给定一个无序的正整数数组和一个目标正整数target，请你在数组中找出和为target的最短连续子数组，并返回其长度。如果不存在符合条件的子数组，返回0；用java语言

```java import java.util.HashMap; import java.util.Map; public class Solution { public int shortestSubarray(int[] nums, int target) { Map<Integer, Integer> map = new HashMap<>(); int sum = 0; map.put(0, -1); int minLength = Integer.MAX_VALUE; int start = 0; for (int i = 0; i < nums.length; i++) { sum += nums[i]; if (map.containsKey(sum - target)) { int length = i - map.get(sum - target); if (length < minLength) { minLength = length; start = map.get(sum - target) + 1; } } map.put(sum, i); } return minLength == Integer.MAX_VALUE ? 0 : minLength; } } ```