国家置顶

app/code/Magento/Backend/etc/adminhtml/system.xml

@@ -363,6 +363,14 @@
                     </depends>
                 </field>
             </group>
+            <group id="top_country" translate="label" type="text" sortOrder="1" showInDefault="1" showInWebsite="1" showInStore="1">
+                <label>Top Country</label>
+                <field id="top_countrys" translate="label" type="text" sortOrder="10" showInDefault="1">
+                    <label>置顶国家</label>
+                    <comment>国家简码为2个大写字母,多个用英文逗号隔开.</comment>
+                </field>
+            </group>
+
         </section>
         <section id="admin" translate="label" type="text" sortOrder="20" showInDefault="1">
             <label>Admin</label>

app/code/Magento/Directory/Model/ResourceModel/Country/CollectionNew.php

+<?php
+namespace Magento\Directory\Model\ResourceModel\Country;
+
+class CollectionNew
+{
+    protected $scopeConfig;
+
+    public function __construct(\Magento\Framework\App\Config\ScopeConfigInterface $scopeConfig)
+    {
+        $this->scopeConfig = $scopeConfig;
+    }
+
+    public function afterToOptionArray(\Magento\Directory\Model\ResourceModel\Country\Collection $subject, $result) {
+        if (!is_array($result) || empty($result)) {
+            return $result;
+        }
+        $topCountry = $this->scopeConfig->getValue('system/top_country/top_countrys');
+        if (!$topCountry) {
+            return $result;
+        }
+        if (!$result[0]['value']) {
+            unset($result[0]);
+        }
+        $topCountry = explode(',', $topCountry);
+        $indexs = array_flip($topCountry);
+        $top = [];
+        $top[0] = ['value' => '', 'label' => ''];
+        foreach ($result as $row) {
+            if (in_array($row['value'], $topCountry)) {
+                $idx = $indexs[$row['value']] + 1;
+                $top[$idx] = $row;
+            }
+        }
+        ksort($top);
+        $top[] = ['value' => '-', 'label' => '---'];
+        $result = array_merge($top, $result);
+        return $result;
+    }
+}
\ No newline at end of file

app/code/Magento/Directory/etc/di.xml

@@ -39,6 +39,9 @@
             </argument>
         </arguments>
     </type>
+    <type name="Magento\Directory\Model\ResourceModel\Country\Collection">
+        <plugin name="new_country_collection" type="Magento\Directory\Model\ResourceModel\Country\CollectionNew"/>
+    </type>
     <preference for="Magento\Directory\Model\Country\Postcode\ConfigInterface" type="Magento\Directory\Model\Country\Postcode\Config" />
     <preference for="Magento\Directory\Model\Country\Postcode\ValidatorInterface" type="Magento\Directory\Model\Country\Postcode\Validator" />
     <preference for="Magento\Directory\Api\CurrencyInformationAcquirerInterface" type="Magento\Directory\Model\CurrencyInformationAcquirer" />