安卓Android源码——日记本.zip

package andy.ham; import java.util.Calendar; import java.util.HashMap; import android.content.ContentProvider; import android.content.ContentUris; import android.content.ContentValues; import android.content.Context; import android.content.UriMatcher; import android.content.res.Resources; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteDatabase.CursorFactory; import android.database.sqlite.SQLiteOpenHelper; import android.database.sqlite.SQLiteQueryBuilder; import android.net.Uri; import android.text.TextUtils; import android.util.Log; import andy.ham.Fields.DiaryColumns; public class LifeDiaryContentProvider extends ContentProvider{ //定义一：日记本中变量 private static final String DATABASE_NAME = "database"; private static final int DATABASE_VERSION = 3; private static final String DIARY_TABLE_NAME = "diary"; private static final int DIARIES = 1; private static final int DIARY_ID = 2; //定义二：UriMatcher。用来匹配URI的类型，是单一的数据请求还是全部数据请求 private static final UriMatcher sUriMatcher; static { sUriMatcher = new UriMatcher(UriMatcher.NO_MATCH); sUriMatcher.addURI(Fields.AUTHORITY, "diaries", DIARIES); sUriMatcher.addURI(Fields.AUTHORITY, "diaries/#", DIARY_ID); } /*定义三：DatabaseHelper。DatabaseHelper是继承SQLiteOpenHelper的 * SQLiteOpenHelper是一个抽象类，有3个函数 onCreate、onUpdate、onOpen（一般不用） */ private DatabaseHelper mOpenHelper; private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); Log.i("jinyan", "DATABASE_VERSION=" + DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { Log.i("jinyan", "onCreate(SQLiteDatabase db)"); String sql = "CREATE TABLE " + DIARY_TABLE_NAME + " (" + DiaryColumns._ID + " INTEGER PRIMARY KEY," + DiaryColumns.TITLE + " TEXT," + DiaryColumns.BODY + " TEXT," + DiaryColumns.CREATED + " TEXT" + ");"; // sql ="CREATE TABLE " + DIARY_TABLE_NAME + " (" + DiaryColumns._ID + " INTEGER PRIMARY KEY," + DiaryColumns.TITLE + " varchar(255)," + DiaryColumns.BODY + " TEXT," + DiaryColumns.CREATED + " TEXT" + ");"; // Log.i("jinyan", "sql="+sql); db.execSQL(sql); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.i("jinyan", " onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)=" + newVersion); db.execSQL("DROP TABLE IF EXISTS diary"); onCreate(db); } } //定义四：getFormateCreatedDate。一个获取当前时间的函数 public static String getFormateCreatedDate() { Calendar calendar = Calendar.getInstance(); String created = calendar.get(Calendar.YEAR) + "年" + calendar.get(Calendar.MONTH) + "月" + calendar.get(Calendar.DAY_OF_MONTH) + "日" + calendar.get(Calendar.HOUR_OF_DAY) + "时" + calendar.get(Calendar.MINUTE) + "分"; return created; } @Override public boolean onCreate() { mOpenHelper = new DatabaseHelper(getContext()); return true; } @Override public Cursor query(Uri uri, String[] projection, String selection, String[] selectionArgs, String sortOrder) { //SQLiteQueryBuilder是一个构造sql查询语句的辅助类 SQLiteQueryBuilder qb = new SQLiteQueryBuilder(); //UriMatcher.match(uri)根据返回值可以判断这次查询请求时，他是请求的全部数据还是某个id的数据 switch (sUriMatcher.match(uri)) { //如果请求是DIARIES只需执行setTables(DIARY_TABLE_NAME) case DIARIES: qb.setTables(DIARY_TABLE_NAME); break; //如果返回值是DIARY_ID，还需要加入where条件 case DIARY_ID: qb.setTables(DIARY_TABLE_NAME); qb.appendWhere(DiaryColumns._ID + "=" + uri.getPathSegments().get(1)); break; default: throw new IllegalArgumentException("Unknown URI " + uri); } String orderBy; if (TextUtils.isEmpty(sortOrder)) { orderBy = Fields.DiaryColumns.DEFAULT_SORT_ORDER; } else { orderBy = sortOrder; } //关键的查询语句，query（）参数为：数据库实例、字符串数组、where部分、字符串数组里面每一项依次代替第三个参数出现问号 //null表示sql语句groupby、第二个null表示sql语句having部分、最后一个参数是排序 SQLiteDatabase db = mOpenHelper.getReadableDatabase(); Cursor c = qb.query(db, projection, selection, selectionArgs, null, null, orderBy); return c; } //返回一个给Uri制定数据的MIME类型，他的返回值如果是以vnd.android.cursor.item开头，那么Uri是单条数据 //如果是以vnd.android.cursor.dir开头的，说明Uri指定的全部数据 public String getType(Uri uri) { switch (sUriMatcher.match(uri)) { case DIARIES: return DiaryColumns.CONTENT_TYPE; case DIARY_ID: return DiaryColumns.CONTENT_ITEM_TYPE; default: throw new IllegalArgumentException("Unknown URI " + uri); } } @Override public Uri insert(Uri uri, ContentValues initialValues) { //判断uri，如果这个uri不是DIARIES类型的，那么这个uri就是一个非法的uri if (sUriMatcher.match(uri) != DIARIES) { throw new IllegalArgumentException("Unknown URI " + uri); } ContentValues values; if (initialValues != null) { values = new ContentValues(initialValues); } else { values = new ContentValues(); } if (values.containsKey(Fields.DiaryColumns.CREATED) == false) { values.put(Fields.DiaryColumns.CREATED, getFormateCreatedDate()); } if (values.containsKey(Fields.DiaryColumns.TITLE) == false) { Resources r = Resources.getSystem(); values.put(Fields.DiaryColumns.TITLE, r .getString(android.R.string.untitled)); } if (values.containsKey(Fields.DiaryColumns.BODY) == false) { values.put(Fields.DiaryColumns.BODY, ""); } //得到一个SQLiteDatabase的实例 SQLiteDatabase db = mOpenHelper.getWritableDatabase(); //负责插入一条记录到数据库当中 long rowId = db.insert(DIARY_TABLE_NAME, Fields.DiaryColumns.BODY, values); if (rowId > 0) { Uri diaryUri = ContentUris.withAppendedId( Fields.DiaryColumns.CONTENT_URI, rowId); //注意：insert（）返回的是一个uri，而不是一个记录id return diaryUri; } throw new SQLException("Failed to insert row into " + uri); } @Override public int delete(Uri uri, String where, String[] whereArgs) { //getWritableDatabase（）方法得到一个string的list SQLiteDatabase db = mOpenHelper.getWritableDatabase(); //得到rowId的值，如果get（0）那值就为diaries String rowId = uri.getPathSegments().get(1); //标准的SQLite删除操作，第一个参数是数据表的名字，第二个相当于SQL语句中的where部分。 return db.delete(DIARY_TABLE_NAME, DiaryColumns._ID + "=" + rowId, null); } @Override public int update(Uri uri, ContentValues values, String where, String[] whereArgs) { //getWritableDatabase（）方法得到SQLiteDatabase的实例 SQLiteDatabase db = mOpenHelper.getWritableDatabase(); //得到rowId的值 String rowId = uri.getPathSegments().get(1); //最后在调用update语句执行更新操作 return db.update(DIARY_TABLE_NAME, values, DiaryColumns._ID + "=" + rowId, null); } }