Update Contact.java

xiaomi/src/data/Contact.java

@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 2010-2011, The MiCode Open Source Community (www.micode.net)
- *  
+ *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
@@ -26,48 +26,68 @@ import android.util.Log;
 import java.util.HashMap;
 
 public class Contact {
+    // 缓存联系人信息的HashMap
     private static HashMap<String, String> sContactCache;
+    // 用于日志标记的常量
     private static final String TAG = "Contact";
 
+    // 定义查询电话号码对应的联系人ID的SQL语句
     private static final String CALLER_ID_SELECTION = "PHONE_NUMBERS_EQUAL(" + Phone.NUMBER
-    + ",?) AND " + Data.MIMETYPE + "='" + Phone.CONTENT_ITEM_TYPE + "'"
-    + " AND " + Data.RAW_CONTACT_ID + " IN "
+            + ") AND " + Data.MIMETYPE + "='" + Phone.CONTENT_ITEM_TYPE + "'"
+            + " AND " + Data.RAW_CONTACT_ID + " IN "
             + "(SELECT raw_contact_id "
             + " FROM phone_lookup"
             + " WHERE min_match = '+')";
 
+    /**
+     * 根据电话号码获取联系人名称
+     * @param context 上下文
+     * @param phoneNumber 电话号码
+     * @return 联系人名称，如果没有找到则返回null
+     */
     public static String getContact(Context context, String phoneNumber) {
         if(sContactCache == null) {
+            // 初始化联系人缓存
             sContactCache = new HashMap<String, String>();
         }
 
+        // 如果缓存中已经存在该电话号码对应的联系人名称，则直接返回
         if(sContactCache.containsKey(phoneNumber)) {
             return sContactCache.get(phoneNumber);
         }
 
-        String selection = CALLER_ID_SELECTION.replace("+",
-                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+        // 替换SQL语句中的电话号码占位符
+        String selection = CALLER_ID_SELECTION.replace("+", PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
         Cursor cursor = context.getContentResolver().query(
                 Data.CONTENT_URI,
-                new String [] { Phone.DISPLAY_NAME },
+                new String[]{ Phone.DISPLAY_NAME },
                 selection,
-                new String[] { phoneNumber },
+                new String[]{ phoneNumber },
                 null);
 
+        // 如果查询结果不为空且游标移动到第一条记录
         if (cursor != null && cursor.moveToFirst()) {
             try {
+                // 获取联系人名称并放入缓存
                 String name = cursor.getString(0);
                 sContactCache.put(phoneNumber, name);
                 return name;
             } catch (IndexOutOfBoundsException e) {
-                Log.e(TAG, " Cursor get string error " + e.toString());
+                // 如果获取联系人名称时发生索引越界异常，则记录错误日志并返回null
+                Log.e(TAG, "Cursor get string error " + e.toString());
                 return null;
             } finally {
+                // 关闭游标
                 cursor.close();
             }
         } else {
+            // 如果没有找到匹配的联系人，则记录日志并返回null
             Log.d(TAG, "No contact matched with number:" + phoneNumber);
             return null;
         }
     }
 }
+```
+
+
+这段代码的主要功能是根据电话号码查询对应的联系人名称，并将结果缓存起来以提高查询效率。