diff --git a/Contact.java b/Contact.java
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+++ b/Contact.java
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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.
+ */
+
+// 定义一个Contact类，用于处理联系人相关信息
+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 {
+    // 定义一个静态HashMap来缓存联系人信息，以提高查询效率
+    private static HashMap<String, String> sContactCache;
+    // 定义日志输出的标签
+    private static final String TAG = "Contact";
+
+    // 定义查询联系人的SQL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名称
+     * 
+     * @param context 上下文对象，用于访问内容提供者
+     * @param phoneNumber 电话号码
+     * @return 如果找到匹配的联系人，则返回联系人名称；否则返回null
+     */
+    public static String getContact(Context context, String phoneNumber) {
+        // 检查缓存是否为空，如果为空则初始化
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();
+        }
+
+        // 检查缓存中是否已经存在该电话号码对应的联系人名称
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber);
+        }
+
+        // 根据电话号码构建查询联系人的SQL语句
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+        // 执行查询
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI,
+                new String [] { Phone.DISPLAY_NAME },
+                selection,
+                new String[] { phoneNumber },
+                null);
+
+        // 处理查询结果
+        if (cursor != null && cursor.moveToFirst()) {
+            try {
+                // 获取联系人名称，并存入缓存中
+                String name = cursor.getString(0);
+                sContactCache.put(phoneNumber, name);
+                return name;
+            } catch (IndexOutOfBoundsException e) {
+                // 日志输出异常信息
+                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，输出日志信息并返回null
+            Log.d(TAG, "No contact matched with number:" + phoneNumber);
+            return null;
+        }
+    }
+}