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.
+ */
+
+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;
+
+/**
+ * 联系人工具类,用于根据电话号码查询联系人信息
+ */
+public class Contact {
+    // 用于缓存电话号码和联系人姓名的映射关系
+    private static HashMap<String, String> sContactCache;
+    // 日志标签
+    private static final String TAG = "Contact";
+
+    /**
+     * 用于查询联系人的SQL语句
+     * PHONE_NUMBERS_EQUAL - 比较电话号码是否相等
+     * MIMETYPE - 指定数据类型为电话号码
+     * RAW_CONTACT_ID - 关联phone_lookup表以获取联系人ID
+     */
+    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 要查询的电话号码
+     * @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Map(如果未初始化)
+        if(sContactCache == null) {
+            sContactCache = new HashMap<String, String>();
+        }
+
+        // 检查缓存中是否已存在该号码对应的联系人
+        if(sContactCache.containsKey(phoneNumber)) {
+            return sContactCache.get(phoneNumber);
+        }
+
+        // 构造查询条件,将电话号码转换为标准格式
+        String selection = CALLER_ID_SELECTION.replace("+",
+                PhoneNumberUtils.toCallerIDMinMatch(phoneNumber));
+        // 查询联系人数据库
+        Cursor cursor = context.getContentResolver().query(
+                Data.CONTENT_URI,
+                new String [] { Phone.DISPLAY_NAME }, // 只查询联系人显示名称
+                selection,
+                new String[] { phoneNumber },
+                null);
+
+        if (cursor != null && cursor.moveToFirst()) {
+            try {
+                // 获取联系人姓名
+                String name = cursor.getString(0);
+                // 将结果存入缓存
+                sContactCache.put(phoneNumber, name);
+                return name;
+            } catch (IndexOutOfBoundsException e) {
+                // 处理游标越界异常
+                Log.e(TAG, " Cursor get string error " + e.toString());
+                return null;
+            } finally {
+                // 确保关闭游标
+                cursor.close();
+            }
+        } else {
+            // 未找到匹配的联系人
+            Log.d(TAG, "No contact matched with number:" + phoneNumber);
+            return null;
+        }
+    }
+}