sqlite 数据库封装类
DatabaseUtil.java(封装的类)
package com.jack.androidbase.tools; import android.content.ContentValues; import android.content.Context; import android.database.Cursor; import android.database.SQLException; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; import android.util.Log; /** * sqlite 数据库操作类 */ public class DatabaseUtil { private static final String TAG = "DatabaseUtil"; /** * Database Name */ private static final String DATABASE_NAME = "student_data"; /** * Database Version */ private static final int DATABASE_VERSION = 1; /** * Table Name */ private static final String DATABASE_TABLE = "tb_student"; /** * Table columns */ public static final String KEY_NAME = "name"; public static final String KEY_GRADE = "grade"; public static final String KEY_ROWID = "_id"; /** * Database creation sql statement */ private static final String CREATE_TABLE = "create table " + DATABASE_TABLE + " (" + KEY_ROWID + " integer primary key autoincrement, " + KEY_NAME + " text not null, " + KEY_GRADE + " text not null);"; /** * Context */ private final Context mCtx; private DatabaseHelper mDbHelper; private SQLiteDatabase mDb; /** * Inner private class. Database Helper class for creating and updating database. */ private static class DatabaseHelper extends SQLiteOpenHelper { DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } /** * onCreate method is called for the 1st time when database doesn't exists. */ @Override public void onCreate(SQLiteDatabase db) { Log.i(TAG, "Creating DataBase: " + CREATE_TABLE); db.execSQL(CREATE_TABLE); } /** * onUpgrade method is called when database version changes. */ @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion); } } /** * Constructor - takes the context to allow the database to be * opened/created * * @param ctx the Context within which to work */ public DatabaseUtil(Context ctx) { this.mCtx = ctx; } /** * This method is used for creating/opening connection * * @return instance of DatabaseUtil * @throws SQLException */ public DatabaseUtil open() throws SQLException { mDbHelper = new DatabaseHelper(mCtx); mDb = mDbHelper.getWritableDatabase(); return this; } /** * This method is used for closing the connection. */ public void close() { mDbHelper.close(); } /** * This method is used to create/insert new record record. * * @param name * @param grade * @return long */ public long insert(String name, String grade) { ContentValues initialValues = new ContentValues(); initialValues.put(KEY_NAME, name); initialValues.put(KEY_GRADE, grade); return mDb.insert(DATABASE_TABLE, null, initialValues); } /** * This method will delete record. * * @param rowId * @return boolean */ public boolean delete(long rowId) { return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; } /** * This method will deleteAll record. * * @return */ public boolean deleteAll() { return mDb.delete(DATABASE_TABLE, " 1 ", null) > 0; } /** * This method will return Cursor holding all the records. * * @return Cursor */ public Cursor fetchAll() { return mDb.query(DATABASE_TABLE, new String[]{KEY_ROWID, KEY_NAME, KEY_GRADE}, null, null, null, null, null); } /** * This method will return Cursor holding the specific record. * * @param id * @return Cursor * @throws SQLException */ public Cursor fetch(long id) throws SQLException { Cursor mCursor = mDb.query(true, DATABASE_TABLE, new String[]{KEY_ROWID, KEY_NAME, KEY_GRADE}, KEY_ROWID + "=" + id, null, null, null, null, null); if (mCursor != null) { mCursor.moveToFirst(); } return mCursor; } /** * This method will update record. * * @param id * @param name * @param standard * @return boolean */ public boolean update(int id, String name, String standard) { ContentValues args = new ContentValues(); args.put(KEY_NAME, name); args.put(KEY_GRADE, standard); return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + id, null) > 0; } }
使用详解:
DatabaseUtil dbUtil = new DatabaseUtil(this);
dbUtil.open();
switch (v.getId()) {
case R.id.other_btn_sqlite_list: //查询
Cursor cursor = dbUtil.fetchAll();
if (cursor != null) {
while (cursor.moveToNext()) {
Log.i(“Student”, “ID:” + cursor.getInt(0) + “,Student Name: ” + cursor.getString(1) +
“,Grade: ” + cursor.getString(2));
}
}
break;
case R.id.other_btn_sqlite_add:
dbUtil.insert(“Prashant Thakkar”, “100”);
Log.i(“Student”, “add over”);
break;
case R.id.other_btn_sqlite_update:
dbUtil.update(1, “aa”, “bb”);
Log.i(“Student”, “update over”);
break;
case R.id.other_btn_sqlite_del:
dbUtil.delete(2);
Log.i(“Student”, “delete over”);
break;
case R.id.other_btn_sqlite_del_all:
dbUtil.deleteAll();
Log.i(“Student”, “delete all over”);
break;
}
dbUtil.close();
参考网址:
https://www.cnblogs.com/sowhat4999/p/4439856.html
https://www.cnblogs.com/ProMonkey/p/5765616.html (有添加单例模式)
本博客地址: wukong1688
本文原文地址:https://www.cnblogs.com/wukong1688/p/10666280.html
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