Circle prop:strokeColor support Array to support gradient ramp

src/utils/random_str.js

@@ -0,0 +1,10 @@
+// 生成随机字符串
+export default function (len = 32) {
+    const $chars = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890';
+    const maxPos = $chars.length;
+    let str = '';
+    for (let i = 0; i < len; i++) {
+        str += $chars.charAt(Math.floor(Math.random() * maxPos));
+    }
+    return str;
+}