diff --git a/app/src/main/java/net/micode/notes/data/Contact.java b/app/src/main/java/net/micode/notes/data/Contact.java
index bec9a8c..178aa79 100644
--- a/app/src/main/java/net/micode/notes/data/Contact.java
+++ b/app/src/main/java/net/micode/notes/data/Contact.java
@@ -27,24 +27,33 @@ import java.util.HashMap;
 
 public class Contact {
     private static HashMap<String, String> sContactCache;// 用于缓存已查询过的联系人信息
-    private static final String TAG = "Contact";
+    private static final String TAG = "Contact";// 用于日志输出的 TAG
 
+    // 查询电话号码与联系人名字匹配的过滤条件
     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 "
             + "(SELECT raw_contact_id "
             + " FROM phone_lookup"
             + " WHERE min_match = '+')";
-
+    /*
+     * 获取电话号码对应的联系人名字
+     * @param context 上下文
+     * @param phoneNumber 电话号码
+     * @return 电话号码对应的联系人名字
+     */
     public static String getContact(Context context, String phoneNumber) {
+        // 如果缓存为空，创建新的缓存对象
         if(sContactCache == null) {
             sContactCache = new HashMap<String, String>();
         }
 
+        // 如果已经查询过该电话号码，直接返回缓存中的联系人名字
         if(sContactCache.containsKey(phoneNumber)) {
             return sContactCache.get(phoneNumber);
         }
 
+        // 构造查询条件
         String selection = CALLER_ID_SELECTION.replace("+",
                 PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
         Cursor cursor = context.getContentResolver().query(
@@ -54,18 +63,20 @@ public class Contact {
                 new String[] { phoneNumber },
                 null);
 
+        // 如果能够查询到联系人信息
         if (cursor != null && cursor.moveToFirst()) {
             try {
                 String name = cursor.getString(0);
+                // 将电话号码与联系人名字加入缓存中
                 sContactCache.put(phoneNumber, name);
                 return name;
             } catch (IndexOutOfBoundsException e) {
                 Log.e(TAG, " Cursor get string error " + e.toString());
                 return null;
             } finally {
-                cursor.close();
+                cursor.close();// 关闭查询结果游标
             }
-        } else {
+        } else {// 如果未能查询到联系人信息，输出日志并返回 null
             Log.d(TAG, "No contact matched with number:" + phoneNumber);
             return null;
         }