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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