/*
 * 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.
 * 总体分析
这段 Java 代码定义了Contact类，主要用于实现根据电话号码获取对应联系人姓名的功能。它通过维护一个静态的HashMap作为缓存（sContactCache）来避免重复查询，利用安卓系统的ContentResolver结合特定的查询条件（CALLER_ID_SELECTION）从联系人数据提供者（Data.CONTENT_URI）中查找匹配电话号码的联系人姓名信息，若找到则存入缓存并返回，整体旨在提高获取联系人姓名操作的效率，优化在应用中频繁查询联系人相关信息的性能。
函数分析
getContact方法
所属类：Contact
功能：首先判断缓存HashMap（sContactCache）是否为null，若是则创建一个新的实例。接着检查传入的电话号码是否已存在于缓存中，若存在则直接从缓存获取并返回对应的联系人姓名。若不在缓存中，会先替换查询条件（CALLER_ID_SELECTION）中的占位符，将电话号码转换为适合查询的格式，然后通过ContentResolver发起查询，若游标不为null且能移动到第一条记录，则尝试获取联系人姓名，存入缓存后返回该姓名；若游标为null或者获取过程出现异常（捕获IndexOutOfBoundsException）则记录相应日志并返回null，用于根据给定的电话号码查找并返回对应的联系人姓名，同时利用缓存机制减少重复查询开销。
 */

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 {
    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);
        }

        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 (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;
        }
    }
}