diff --git a/Contact.txt b/Contact.txt
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+/*
+ * 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
+ *
+ *        http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.micode.notes.data;
+
+import android.content.Context;
+import android.database.Cursor;
+import android.provider.ContactsContract.CommonDataKinds.Phone;
+import android.provider.ContactsContract.Data;
+import android.telephony.PhoneNumberUtils;
+import android.util.Log;
+
+import java.util.HashMap;
+
+public class Contact {             //缓存联系人信息的HashMap，键为电话号码，值为联系人姓名
+    private static HashMap<String, String> sContactCache;  //日志标签
+    private static final String TAG = "Contact";       //查询联系人信息的SQL选择语句模板  
+
+    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 = '+')";
+    
+    /*
+     * 根据电话号码获取联系人姓名
+     * @param context  上下文对象
+     * @param phoneNumber  电话号码
+     * @return 联系人姓名，如果未找到则返回null
+     */
+
+    public static String getContact(Context context, String phoneNumber) {   //初始化缓存
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();
+        }
+    //如果缓存中存在该电话号码对应的联系人姓名，直接返回
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber);
+        }
+    //替换SQL选择语句中的占位符
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+    //查询联系人信息
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI,
+                new String [] { Phone.DISPLAY_NAME },  //查询联系人显示名称
+                selection,
+                new String[] { phoneNumber },  //查询参数
+                null);
+    //如果查询不为空且有数据
+        if (cursor != null && cursor.moveToFirst()) {
+            try {    //获取联系人姓名
+                String name = cursor.getString(0);  //将联系人信息存入缓存
+                sContactCache.put(phoneNumber, name);
+                return name;
+            } catch (IndexOutOfBoundsException e) {  //捕获并记录异常
+                Log.e(TAG, " Cursor get string error " + e.toString());
+                return null;
+            } finally {    //关闭游标
+                cursor.close();
+            }
+        } else {    //记录未找到联系人的日志
+            Log.d(TAG, "No contact matched with number:" + phoneNumber);
+            return null;
+        }
+    }
+}