test/src/data/NotesProvider.java

package net.micode.notes.data;

import android.app.SearchManager;
import android.content.ContentProvider;
import android.content.ContentUris;
import android.content.ContentValues;
import android.content.Intent;
import android.content.UriMatcher;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.net.Uri;
import android.text.TextUtils;
import android.util.Log;

import net.micode.notes.R;
import net.micode.notes.data.Notes.DataColumns;
import net.micode.notes.data.Notes.NoteColumns;
import net.micode.notes.data.NotesDatabaseHelper.TABLE;

/**
 * 便签内容提供者，实现Android ContentProvider接口
 * 负责管理便签数据的增删改查，并支持搜索建议功能
 */
public class NotesProvider extends ContentProvider {
    // URI匹配器，用于解析不同的URI请求
    private static final UriMatcher mMatcher;
    // 数据库帮助类实例
    private NotesDatabaseHelper mHelper;
    // 日志标签
    private static final String TAG = "NotesProvider";

    // URI匹配器的类型常量
    private static final int URI_NOTE            = 1;        // 便签列表
    private static final int URI_NOTE_ITEM       = 2;        // 单个便签
    private static final int URI_DATA            = 3;        // 便签数据列表
    private static final int URI_DATA_ITEM       = 4;        // 单个便签数据
    private static final int URI_SEARCH          = 5;        // 搜索请求
    private static final int URI_SEARCH_SUGGEST  = 6;        // 搜索建议请求

    static {
        // 初始化URI匹配器
        mMatcher = new UriMatcher(UriMatcher.NO_MATCH);
        // 匹配便签列表URI：content://micode_notes/note
        mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE);
        // 匹配单个便签URI：content://micode_notes/note/123
        mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM);
        // 匹配便签数据列表URI：content://micode_notes/data
        mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA);
        // 匹配单个便签数据URI：content://micode_notes/data/456
        mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM);
        // 匹配搜索URI：content://micode_notes/search
        mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH);
        // 匹配搜索建议URI（带查询词路径）
        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST);
        mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST);
    }

    /**
     * 搜索投影字段定义
     * 包含便签ID、搜索建议文本、图标、点击动作等
     * x'0A' 表示SQLite中的换行符，替换为空格并修剪前后空白
     */
    private static final String NOTES_SEARCH_PROJECTION = NoteColumns.ID + ","
        + NoteColumns.ID + " AS " + SearchManager.SUGGEST_COLUMN_INTENT_EXTRA_DATA + ","  // 传递便签ID到搜索结果
        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_1 + ","  // 第一行文本（摘要）
        + "TRIM(REPLACE(" + NoteColumns.SNIPPET + ", x'0A','')) AS " + SearchManager.SUGGEST_COLUMN_TEXT_2 + ","  // 第二行文本（重复摘要，适配UI）
        + R.drawable.search_result + " AS " + SearchManager.SUGGEST_COLUMN_ICON_1 + ","  // 搜索结果图标资源ID
        + "'" + Intent.ACTION_VIEW + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_ACTION + ","  // 点击动作：查看便签
        + "'" + Notes.TextNote.CONTENT_TYPE + "' AS " + SearchManager.SUGGEST_COLUMN_INTENT_DATA;  // 数据类型：文本便签

    /**
     * 便签内容搜索查询语句
     * 查询条件：摘要包含搜索词、非回收站文件夹、类型为普通便签
     */
    private static String NOTES_SNIPPET_SEARCH_QUERY = "SELECT " + NOTES_SEARCH_PROJECTION
        + " FROM " + TABLE.NOTE
        + " WHERE " + NoteColumns.SNIPPET + " LIKE ?"
        + " AND " + NoteColumns.PARENT_ID + "<>" + Notes.ID_TRASH_FOLER  // 排除回收站
        + " AND " + NoteColumns.TYPE + "=" + Notes.TYPE_NOTE;           // 仅普通便签

    @Override
    public boolean onCreate() {
        // 获取数据库帮助类的单例实例
        mHelper = NotesDatabaseHelper.getInstance(getContext());
        return true;
    }

    @Override
    public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs,
            String sortOrder) {
        Cursor c = null;
        SQLiteDatabase db = mHelper.getReadableDatabase();
        String id = null;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 查询便签列表
                c = db.query(TABLE.NOTE, projection, selection, selectionArgs, null, null, sortOrder);
                break;
            case URI_NOTE_ITEM:
                // 获取路径中的便签ID（如note/123中的123）
                id = uri.getPathSegments().get(1);
                // 查询单个便签，拼接条件：ID=路径ID + 额外查询条件
                c = db.query(TABLE.NOTE, projection, NoteColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
                break;
            case URI_DATA:
                // 查询便签数据列表
                c = db.query(TABLE.DATA, projection, selection, selectionArgs, null, null, sortOrder);
                break;
            case URI_DATA_ITEM:
                // 获取路径中的数据ID（如data/456中的456）
                id = uri.getPathSegments().get(1);
                // 查询单个便签数据
                c = db.query(TABLE.DATA, projection, DataColumns.ID + "=" + id
                        + parseSelection(selection), selectionArgs, null, null, sortOrder);
                break;
            case URI_SEARCH:
            case URI_SEARCH_SUGGEST:
                // 搜索和搜索建议不支持排序、投影等参数
                if (sortOrder != null || projection != null) {
                    throw new IllegalArgumentException(
                            "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query");
                }

                String searchString = null;
                if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) {
                    // 从路径中获取搜索词（如suggest_query/关键词）
                    if (uri.getPathSegments().size() > 1) {
                        searchString = uri.getPathSegments().get(1);
                    }
                } else {
                    // 从查询参数中获取搜索词（如pattern=关键词）
                    searchString = uri.getQueryParameter("pattern");
                }

                if (TextUtils.isEmpty(searchString)) {
                    return null;
                }

                try {
                    // 拼接模糊查询参数（%关键词%）
                    searchString = String.format("%%%s%%", searchString);
                    // 执行原生SQL查询搜索结果
                    c = db.rawQuery(NOTES_SNIPPET_SEARCH_QUERY, new String[] { searchString });
                } catch (IllegalStateException ex) {
                    Log.e(TAG, "got exception: " + ex.toString());
                }
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        if (c != null) {
            // 设置查询结果的通知URI，以便数据变化时更新界面
            c.setNotificationUri(getContext().getContentResolver(), uri);
        }
        return c;
    }

    @Override
    public Uri insert(Uri uri, ContentValues values) {
        SQLiteDatabase db = mHelper.getWritableDatabase();
        long dataId = 0, noteId = 0, insertedId = 0;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 插入新便签
                insertedId = noteId = db.insert(TABLE.NOTE, null, values);
                break;
            case URI_DATA:
                // 插入便签数据时需关联便签ID
                if (values.containsKey(DataColumns.NOTE_ID)) {
                    noteId = values.getAsLong(DataColumns.NOTE_ID);
                } else {
                    Log.d(TAG, "Wrong data format without note id:" + values.toString());
                }
                insertedId = dataId = db.insert(TABLE.DATA, null, values);
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        // 通知便签数据变化（更新UI）
        if (noteId > 0) {
            getContext().getContentResolver().notifyChange(
                    ContentUris.withAppendedId(Notes.CONTENT_NOTE_URI, noteId), null);
        }
        if (dataId > 0) {
            getContext().getContentResolver().notifyChange(
                    ContentUris.withAppendedId(Notes.CONTENT_DATA_URI, dataId), null);
        }
        // 返回插入记录的URI（带ID）
        return ContentUris.withAppendedId(uri, insertedId);
    }

    @Override
    public int delete(Uri uri, String selection, String[] selectionArgs) {
        int count = 0;
        String id = null;
        SQLiteDatabase db = mHelper.getWritableDatabase();
        boolean deleteData = false;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
                // 删除便签列表，排除系统文件夹（ID>0）
                selection = "(" + selection + ") AND " + NoteColumns.ID + ">0 ";
                count = db.delete(TABLE.NOTE, selection, selectionArgs);
                break;
            case URI_NOTE_ITEM:
                // 删除单个便签，获取路径中的ID
                id = uri.getPathSegments().get(1);
                long noteId = Long.valueOf(id);
                // 系统文件夹（ID≤0）不允许删除
                if (noteId <= 0) {
                    break;
                }
                count = db.delete(TABLE.NOTE,
                        NoteColumns.ID + "=" + id + parseSelection(selection), selectionArgs);
                break;
            case URI_DATA:
            case URI_DATA_ITEM:
                // 删除便签数据
                count = db.delete(mMatcher.match(uri) == URI_DATA ? TABLE.DATA : TABLE.DATA,
                        mMatcher.match(uri) == URI_DATA_ITEM ? DataColumns.ID + "=" + id + parseSelection(selection) : selection,
                        selectionArgs);
                deleteData = true;
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        if (count > 0) {
            // 通知数据变化
            if (deleteData) {
                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
            }
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    @Override
    public int update(Uri uri, ContentValues values, String selection, String[] selectionArgs) {
        int count = 0;
        String id = null;
        SQLiteDatabase db = mHelper.getWritableDatabase();
        boolean updateData = false;
        switch (mMatcher.match(uri)) {
            case URI_NOTE:
            case URI_NOTE_ITEM:
                // 更新便签时增加版本号（乐观锁机制）
                increaseNoteVersion(mMatcher.match(uri) == URI_NOTE_ITEM ? Long.valueOf(uri.getPathSegments().get(1)) : -1, selection, selectionArgs);
                // 执行更新操作
                count = db.update(mMatcher.match(uri) == URI_NOTE ? TABLE.NOTE : TABLE.NOTE,
                        values,
                        mMatcher.match(uri) == URI_NOTE_ITEM ? NoteColumns.ID + "=" + uri.getPathSegments().get(1) + parseSelection(selection) : selection,
                        selectionArgs);
                break;
            case URI_DATA:
            case URI_DATA_ITEM:
                // 更新便签数据
                count = db.update(mMatcher.match(uri) == URI_DATA ? TABLE.DATA : TABLE.DATA,
                        values,
                        mMatcher.match(uri) == URI_DATA_ITEM ? DataColumns.ID + "=" + uri.getPathSegments().get(1) + parseSelection(selection) : selection,
                        selectionArgs);
                updateData = true;
                break;
            default:
                throw new IllegalArgumentException("Unknown URI " + uri);
        }
        if (count > 0) {
            // 通知数据变化
            if (updateData) {
                getContext().getContentResolver().notifyChange(Notes.CONTENT_NOTE_URI, null);
            }
            getContext().getContentResolver().notifyChange(uri, null);
        }
        return count;
    }

    /**
     * 拼接额外查询条件（在原有条件前添加" AND "）
     * @param selection 原始查询条件
     * @return 拼接后的条件字符串
     */
    private String parseSelection(String selection) {
        return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : "");
    }

    /**
     * 增加便签版本号（用于数据同步或乐观锁）
     * @param id 单个便签ID（-1表示批量更新）
     * @param selection 批量更新条件
     * @param selectionArgs 条件参数
     */
    private void increaseNoteVersion(long id, String selection, String[] selectionArgs) {
        StringBuilder sql = new StringBuilder(120);
        sql.append("UPDATE ");
        sql.append(TABLE.NOTE);
        sql.append(" SET ");
        sql.append(NoteColumns.VERSION);
        sql.append("=" + NoteColumns.VERSION + "+1 ");

        if (id > 0 || !TextUtils.isEmpty(selection)) {
            sql.append(" WHERE ");
        }
        if (id > 0) {
            sql.append(NoteColumns.ID + "=" + String.valueOf(id));
        }
        if (!TextUtils.isEmpty(selection)) {
            // 替换占位符?为实际参数
            String selectString = id > 0 ? parseSelection(selection) : selection;
            for (String args : selectionArgs) {
                selectString = selectString.replaceFirst("\\?", args);
            }
            sql.append(selectString);
        }
        // 执行SQL更新
        mHelper.getWritableDatabase().execSQL(sql.toString());
    }

    @Override
    public String getType(Uri uri) {
        // TODO: 实现获取MIME类型的逻辑（当前未实现）
        return null;
    }
}