Android 笔记 - SQLite简单demo

1 Bean类

public class User {
private int Uid;
private String Uname;
private String Uaddress;

public User(int uid, String uname, String uaddress) {
super();
Uid = uid;
Uname = uname;
Uaddress = uaddress;
}

public User(String uname, String uaddress) {
super();
Uname = uname;
Uaddress = uaddress;
}

public int getUid() {
return Uid;
}

public void setUid(int uid) {
Uid = uid;
}

public String getUname() {
return Uname;
}

public void setUname(String uname) {
Uname = uname;
}

public String getUaddress() {
return Uaddress;
}

public void setUaddress(String uaddress) {
Uaddress = uaddress;
}

public User() {
super();
}

@Override
public String toString() {
return "User [Uid=" + Uid + ", Uname=" + Uname + ", Uaddress="
+ Uaddress + "]";
}

}

2 数据库帮助类

public class SQLiteOpenHelper extends android.database.sqlite.SQLiteOpenHelper {
private static final String dbname = "test.db";
public static final String dbtable = "user";

public SQLiteOpenHelper(Context context, String name,
CursorFactory factory, int version) {
super(context, dbname, factory, version);
// TODO Auto-generated constructor stub
}

@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("create table "+dbtable+"(uid integer primary key autoincrement, uname varchar(20), uaddress varchar(20))");
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
// TODO Auto-generated method stub

}

}

分析：

数据库创建看上去是在

super(context, dbname, factory, version);

时创建的，其实不然，Android官方文档指出，只有第一次调用getReadableDataBase或者getWritableDataBase时才会调用创建数据库，大家可以自己测试一下。

3 数据库操作类

public class DBDao {
SQLiteOpenHelper SQLiteOpenHelper;

public DBDao(Context context) {
this.SQLiteOpenHelper = new SQLiteOpenHelper(context, null, null, 1);
}

/**
* 添加一条数据
* @param user
*/
public void save(User user) {
SQLiteDatabase db = SQLiteOpenHelper.getWritableDatabase();
db.execSQL("insert into user(uname,uaddress) values(?,?)",
new Object[] { user.getUname(), user.getUaddress() });
db.close();
}

/**
* 删除一条数据
*
* @param uid
*/
public void delete(Integer uid) {
SQLiteDatabase db = SQLiteOpenHelper.getWritableDatabase();
db.execSQL("delete from user where uid=?", new Object[] { uid });
db.close();
}

/**
* 更新一条数据
*
* @param user
*/
public void update(User user) {
SQLiteDatabase db = SQLiteOpenHelper.getWritableDatabase();
db.execSQL(
"update user set uname=?,uaddress=? where uid=?",
new Object[] { user.getUname(), user.getUaddress(),
user.getUid() });
db.close();
}

/**
* 查找全部数据
*
* @param uid
*/

public ArrayList<User> findAll(){
SQLiteDatabase db = SQLiteOpenHelper.getReadableDatabase();
/**
* Query the given table, returning a {@link Cursor} over the result set.
*
* @param table The table name to compile the query against.
* @param columns A list of which columns to return. Passing null will
*            return all columns, which is discouraged to prevent reading
*            data from storage that isn't going to be used.
* @param selection A filter declaring which rows to return, formatted as an
*            SQL WHERE clause (excluding the WHERE itself). Passing null
*            will return all rows for the given table.
* @param selectionArgs You may include ?s in selection, which will be
*         replaced by the values from selectionArgs, in order that they
*         appear in the selection. The values will be bound as Strings.
* @param groupBy A filter declaring how to group rows, formatted as an SQL
*            GROUP BY clause (excluding the GROUP BY itself). Passing null
*            will cause the rows to not be grouped.
* @param having A filter declare which row groups to include in the cursor,
*            if row grouping is being used, formatted as an SQL HAVING
*            clause (excluding the HAVING itself). Passing null will cause
*            all row groups to be included, and is required when row
*            grouping is not being used.
* @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
*            (excluding the ORDER BY itself). Passing null will use the
*            default sort order, which may be unordered.
* @return A {@link Cursor} object, which is positioned before the first entry. Note that
* {@link Cursor}s are not synchronized, see the documentation for more details.
* @see Cursor
*/
Cursor cursor = db.query(SQLiteOpenHelper.dbtable, null, null, null, null, null, null);
ArrayList<User> list = new ArrayList<User>();
if(null != cursor){
while (cursor.moveToNext()) {
int uid2 = cursor.getInt(cursor.getColumnIndex("uid"));
String uname = cursor.getString(cursor.getColumnIndex("uname"));
String uaddress = cursor.getString(cursor
.getColumnIndex("uaddress"));
User user = new User();
user.setUid(uid2);
user.setUname(uname);
user.setUaddress(uaddress);
list.add(user);
}
cursor.close();
return list;
}
return null;
}

/**
* 查找一条数据
*
* @param uid
*/
public User find(Integer uid) {
SQLiteDatabase db = SQLiteOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select * from user where uid=?",
new String[] { uid.toString() });
if (cursor.moveToFirst()) {
int uid2 = cursor.getInt(cursor.getColumnIndex("uid"));
String uname = cursor.getString(cursor.getColumnIndex("uname"));
String uaddress = cursor.getString(cursor
.getColumnIndex("uaddress"));
User user = new User();
user.setUid(uid2);
user.setUname(uname);
user.setUaddress(uaddress);
return user;
}
cursor.close();
return null;
}

/**
* 分页查找数据
*
* @param offset
*            跳过多少条数据
* @param maxResult
*            每页多少条数据
* @return
*/
public List<User> getScrollData(int offset, int maxResult) {
List<User> users = new ArrayList<User>();
SQLiteDatabase db = SQLiteOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery(
"select * from user order by uid asc limit ?,?", new String[] {
String.valueOf(offset), String.valueOf(maxResult) });
while (cursor.moveToNext()) {
int uid2 = cursor.getInt(cursor.getColumnIndex("uid"));
String uname = cursor.getString(cursor.getColumnIndex("uname"));
String uaddress = cursor.getString(cursor
.getColumnIndex("uaddress"));
User user = new User();
user.setUid(uid2);
user.setUname(uname);
user.setUaddress(uaddress);
users.add(user);
}
return users;
}

/**
* 获取数据总数
*
* @return
*/
public long getCount() {
SQLiteDatabase db = SQLiteOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select count(*) from user", null);
cursor.moveToFirst();
long reslut = cursor.getLong(0);
return reslut;
}
}

4 主界面

public class MainActivity extends Activity {
private static final String TAG = "MainActivity";

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

MyAsyncTask tast = new MyAsyncTask();
tast.execute();
}

public class MyAsyncTask extends AsyncTask<String, Integer, byte []>{

@Override
protected void onPreExecute() {
Log.v(TAG,"onPreExecute");
super.onPreExecute();
}

@Override
protected byte[] doInBackground(String... params) {
Log.v(TAG,"doInBackground");
DBDao dbDao = new DBDao(MainActivity.this);
User user = new User("chj", "新民");

dbDao.save(user);
ArrayList<User> users = dbDao.findAll();
//在这个方法可以调用onProgressUpdate来更新进度
return users.toString().getBytes();//return给了onPostExecute
}

@Override
protected void onProgressUpdate(Integer... values) {
Log.v(TAG,"onProgressUpdate");
super.onProgressUpdate(values);
}

@Override
protected void onPostExecute(byte[] result) {
Log.v(TAG,"onPostExecute");
Toast.makeText(MainActivity.this, ""+new String(result), Toast.LENGTH_LONG).show();
super.onPostExecute(result);
}

}
}

Async资料参考

http://www.cnblogs.com/xiaoluo501395377/p/3430542.html

这篇文章的原型是其他网站上的，原文找不到了，这里就写成转载吧。