import android.content.ContentProvider; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.net.Uri; import android.text.TextUtils; import android.util.Log; import android.app.SearchManager; import net.micode.notes.data.Notes; // 定义 NotesProvider 类 public class NotesProvider extends ContentProvider { // UriMatcher 用于匹配 Uri private static final UriMatcher mMatcher; private NotesDatabaseHelper mHelper; private static final String TAG = "NotesProvider"; private static final int URI_NOTE = 1; private static final int URI_NOTE_ITEM = 2; private static final int URI_DATA = 3; private static final int URI_DATA_ITEM = 4; private static final int URI_SEARCH = 5; private static final int URI_SEARCH_SUGGEST = 6; static { // 创建 UriMatcher 时,调用 UriMatcher(UriMatcher.NO_MATCH) 表示不匹配任何路径的返回码 mMatcher = new UriMatcher(UriMatcher.NO_MATCH); // 把需要匹配 Uri 路径全部给注册上 mMatcher.addURI(Notes.AUTHORITY, "note", URI_NOTE); mMatcher.addURI(Notes.AUTHORITY, "note/#", URI_NOTE_ITEM); mMatcher.addURI(Notes.AUTHORITY, "data", URI_DATA); mMatcher.addURI(Notes.AUTHORITY, "data/#", URI_DATA_ITEM); mMatcher.addURI(Notes.AUTHORITY, "search", URI_SEARCH); mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY, URI_SEARCH_SUGGEST); mMatcher.addURI(Notes.AUTHORITY, SearchManager.SUGGEST_URI_PATH_QUERY + "/*", URI_SEARCH_SUGGEST); } // 声明 NOTES_SEARCH_PROJECTION private static final String NOTES_SEARCH_PROJECTION = "……"; // 声明 NOTES_SNIPPET_SEARCH_QUERY private static String NOTES_SNIPPET_SEARCH_QUERY = "……"; // 定义 mHelper 初始化方法 @Override public boolean onCreate() { mHelper = NotesDatabaseHelper.getInstance(getContext()); return true; } @Override // 查询 uri 在数据库中对应的位置 public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { Cursor c = null; // 获取可读数据库 SQLiteDatabase db = mHelper.getReadableDatabase(); String id = null; // 匹配查找 uri switch (mMatcher.match(uri)) { // 对于不同的匹配值,在数据库中查找相应的条目 case URI_NOTE: c = db.query(NotesDatabaseHelper.TABLE.NOTE, projection, selection, selectionArgs, null, null, sortOrder); break; // 这里省略原代码中 query 方法里的省略部分 case URI_SEARCH_SUGGEST: if (sortOrder != null || projection != null) { // 不合法的参数异常 throw new IllegalArgumentException( "do not specify sortOrder, selection, selectionArgs, or projection" + "with this query"); } String searchString = null; if (mMatcher.match(uri) == URI_SEARCH_SUGGEST) { if (uri.getPathSegments().size() > 1) { // getPathSegments() 方法得到一个 String 的 List, // 在 uri.getPathSegments().get(1) 为第 2 个元素 searchString = uri.getPathSegments().get(1); } } // 这里省略原代码中 case URI_SEARCH_SUGGEST 里的省略部分 break; } return c; } // 将字符串解析成规定格式 private String parseSelection(String selection) { return (!TextUtils.isEmpty(selection) ? " AND (" + selection + ')' : ""); } // 更新一个 uri @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; // 这里省略原代码中 update 方法里的省略部分 return count; } // 增加一个 noteVersion private void increaseNoteVersion(long id, String selection, String[] selectionArgs) { StringBuilder sql = new StringBuilder(120); sql.append("UPDATE "); sql.append(NotesDatabaseHelper.TABLE.NOTE); sql.append(" SET "); sql.append(Notes.NoteColumns.VERSION); sql.append("=" + Notes.NoteColumns.VERSION + "+1 "); if (id > 0 || !TextUtils.isEmpty(selection)) { sql.append(" WHERE "); } if (id > 0) { sql.append(Notes.NoteColumns.ID + "=" + String.valueOf(id)); } if (!TextUtils.isEmpty(selection)) { String selectString = id > 0 ? parseSelection(selection) : selection; for (String args : selectionArgs) { selectString = selectString.replaceFirst("\\?", args); } sql.append(selectString); } // execSQL() 方法可以执行 insert、delete、update 和 CREATE TABLE 之类有更改行为的 SQL 语句 mHelper.getWritableDatabase().execSQL(sql.toString()); } @Override public String getType(Uri uri) { return null; } @Override public Uri insert(Uri uri, ContentValues values) { // 这里可以添加插入数据的逻辑 return null; } @Override public int delete(Uri uri, String selection, String[] selectionArgs) { // 这里可以添加删除数据的逻辑 return 0; } }