diff --git a/Notes-master2/src/net/micode/notes/data/Contact.java b/Notes-master2/src/net/micode/notes/data/Contact.java
index d97ac5d..aa79c49 100644
--- a/Notes-master2/src/net/micode/notes/data/Contact.java
+++ b/Notes-master2/src/net/micode/notes/data/Contact.java
@@ -25,49 +25,38 @@ import android.util.Log;
 
 import java.util.HashMap;
 
-public class Contact {
-    private static HashMap<String, String> sContactCache;
-    private static final String TAG = "Contact";
-
-    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 = '+')";
-
-    public static String getContact(Context context, String phoneNumber) {
-        if(sContactCache == null) {
-            sContactCache = new HashMap<String, String>();
-        }
-
-        if(sContactCache.containsKey(phoneNumber)) {
-            return sContactCache.get(phoneNumber);
-        }
+public static String getContact(Context context, String phoneNumber) {
+    if(sContactCache == null) { //如果缓存为空则创建一个新的 HashMap
+        sContactCache = new HashMap<String, String>();
+    }
 
-        String selection = CALLER_ID_SELECTION.replace("+",
-                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
-        Cursor cursor = context.getContentResolver().query(
-                Data.CONTENT_URI,
-                new String [] { Phone.DISPLAY_NAME },
-                selection,
-                new String[] { phoneNumber },
-                null);
+    if(sContactCache.containsKey(phoneNumber)) { //如果缓存中已存在对应的电话号码则返回其对应的联系人姓名
+        return sContactCache.get(phoneNumber);
+    }
 
-        if (cursor != null && cursor.moveToFirst()) {
-            try {
-                String name = cursor.getString(0);
-                sContactCache.put(phoneNumber, name);
-                return name;
-            } catch (IndexOutOfBoundsException e) {
-                Log.e(TAG, " Cursor get string error " + e.toString());
-                return null;
-            } finally {
-                cursor.close();
-            }
-        } else {
-            Log.d(TAG, "No contact matched with number:" + phoneNumber);
-            return null;
+    //否则根据电话号码查询联系人姓名
+    String selection = CALLER_ID_SELECTION.replace("+",
+            PhoneNumberUtils.toCallerIDMinMatch(phoneNumber)); //将 "+" 替换为待查询电话号码的最小完全匹配
+    Cursor cursor = context.getContentResolver().query(
+            Data.CONTENT_URI, //uri为ContentProvider提供的数据查询接口的位置(Data.CONTENT_URI)
+            new String [] { Phone.DISPLAY_NAME }, //需要查询的数据项，查询联系人姓名
+            selection, //查询条件
+            new String[] { phoneNumber }, //占位符对应的实际参数
+            null); //排序方式为空
+
+    if (cursor != null && cursor.moveToFirst()) { //如果查询结果非空，获取查询结果中的第一条记录
+        try {
+            String name = cursor.getString(0); //获取联系人姓名
+            sContactCache.put(phoneNumber, name); //将电话号码及其联系人姓名加入 HashMap 缓存中
+            return name; //返回联系人姓名
+        } catch (IndexOutOfBoundsException e) { //处理异常
+            Log.e(TAG, " Cursor get string error " + e.toString());
+            return null; //返回null
+        } finally {
+            cursor.close(); //释放cursor
         }
+    } else { //如果返回为空，打印调试信息并返回null
+        Log.d(TAG, "No contact matched with number:" + phoneNumber);
+        return null; //返回null
     }
 }