在android中建立sqlite连接的最佳方式是什么？

我见过很多与sqlite连接相关的例子。但是我还没有找到任何合适的代码。任何人请描述一步一步sqlite连接过程的所有可能性

首先，您需要创建一个数据库。 可以通过创建扩展SQLiteOpenHelper的DatabaseHelper类来实现这一点。 重写onCreate（）和onUpgrade（）方法：

当你的应用程序第一次启动时，Android操作系统将调用你的onCreate（）方法来创建数据库和表

创建MyTable类

public class MyTable {

    // Database table
    public static final String TABLE_NAME = "mytable";

    // Create statement
    private static final String SQL_CREATE_MY_TABLE = 
        "CREATE TABLE " + TABLE_NAME + "(" + MyTableContract.SQL_CREATE_COLUMN_CLAUSE + ");";


    public static void onCreate(SQLiteDatabase db) {
         db.execSQL(SQL_CREATE_MY_TABLE);
    }

    public static void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + TABLE_NAME);
        onCreate(db);
    }
}

在这里，您可以创建表并对其进行升级。仅创建合同类的委托。将所有列活动提取到合同类中是一个很好的做法。升级，在大多数情况下可以删除并重新创建表，除非您想保留一些数据，如登录

创建表格合同

public class MyTableContract {

// COLUMNS
public static final String COLUMN_ID    = "_id";
public static final String COLUMN_NAME  = "name";
public static final String COLUMN_AGE   = "age";


// Create clause
public static final String SQL_CREATE_COLUMN_CLAUSE = 
    COLUMN_ID       + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
    COLUMN_NAME     + " TEXT, " +
    COLUMN_AGE      + " INTEGER";

// Query projection
public static final String[] QUERY_PROJECTION =
{
    COLUMN_ID,
    COLUMN_NAME,
    COLUMN_AGE
};

// Selection clause - return all rows
public static final String SELECTION_CLAUSE = null;

// Selection arguments
public static final String[] SELECTION_ARGS = null;

// Use default sort order
public static final String QUERY_SORT_ORDER = null;
}

在这里，您可以指定在查询数据库时要创建哪些列以及要返回哪些列

插入/查询。 然后，无论您想在何处插入/查询数据库，都可以执行以下操作：

// Create a Database Helper
private DatabaseHelper mDbHelper = new DatabaseHelper(getContext());

// Get the writable database to Insert
SQLiteDatabase db = mDbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put(MyTableContract.COLUMN_NAME, "eduard");
values.put(MyTableContract.COLUMN_AGE,   32);
long insertId = database.insert(MyTable.TABLE_NAME, null, values);

// Get the readable database to Query
SQLiteDatabase db = mDbHelper.getReadableDatabase();
Cursor cursor = database.query(MyTable.TABLE_NAME, MyTableContract.QUERY_PROJECTION, MyTableContract.COLUMN_AGE + " = 32", null, null, null, null);
cursor.moveToFirst();
String nameReturned = cursor.getString(0);
cursor.close();

---

尝试创建两个不同的文件，一个用于数据库处理程序，另一个用于简单地编写查询。在数据库处理程序中，将其扩展到SQLiteOpenhelper并实现方法。在oncreate（）中方法根据需要创建数据库，并在查询文件中根据需要创建方法，在方法中编写查询并在活动中调用它们的对象

 public class Database_Helper {
   private Context context;
public static String DB_name = "demo.sqlite";
Demo_DBHelper dh;
SQLiteDatabase sdb;

private static class Demo_DBHelper extends SQLiteOpenHelper {

    public Demo_DBHelper(Context context) {

        super(context, DB_name, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        System.out.println("On Create Called");
        db.execSQL("Create TABLE IF NOT EXISTS Contact_Detail(mid INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR,phonenumber VARCHAR)");

    }

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

        db.execSQL("DROP TABLE IF EXISTS Contact_Detail");

        // db.execSQL("DROP TABLE IF EXISTS CommunityDetails");
    }

}

public Database_Helper(Context c) {
    context = c;
}

public Database_Helper Open() throws SQLiteException {
    dh = new Demo_DBHelper(context);
    sdb = dh.getWritableDatabase();
    return this;
}

public void close() {
    dh.close();
}

public void clearData() {
    sdb.execSQL("DROP TABLE IF EXISTS Contact_Detail");

}

public Cursor getContactDetail() {

    String st = "SELECT * from Contact_Detail";

    Cursor rs_message = sdb.rawQuery(st, null);
    return rs_message;

}

public void add_contact(String name, String phonenumber) {

    ContentValues cv = new ContentValues();
    cv.put("name", name);
    cv.put("phonenumber", phonenumber);
    sdb.insert("Contact_Detail", null, cv);

}

public void removephone(int phonenumber) {

    String str = "SELECT * FROM Contact_Detail where phonenumber='"
            + phonenumber + "' ";
    Cursor rs_message = sdb.rawQuery(str, null);
    if (rs_message.moveToFirst()) {

        String st = "DELETE FROM Contact_Detail where phonenumber='"
                + phonenumber + "' ";
        sdb.execSQL(st);
    }

}

public void update_contactdetail(String phonenumber, String name) {

    ContentValues cv = new ContentValues();
    cv.put("name", "" + name);

    sdb.update("Contact_Detail", cv, "phonenumber=?",
            new String[] { phonenumber });

}

}

 public class Database_Helper {
   private Context context;
public static String DB_name = "demo.sqlite";
Demo_DBHelper dh;
SQLiteDatabase sdb;

private static class Demo_DBHelper extends SQLiteOpenHelper {

    public Demo_DBHelper(Context context) {

        super(context, DB_name, null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        System.out.println("On Create Called");
        db.execSQL("Create TABLE IF NOT EXISTS Contact_Detail(mid INTEGER PRIMARY KEY AUTOINCREMENT,name VARCHAR,phonenumber VARCHAR)");

    }

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

        db.execSQL("DROP TABLE IF EXISTS Contact_Detail");

        // db.execSQL("DROP TABLE IF EXISTS CommunityDetails");
    }

}

public Database_Helper(Context c) {
    context = c;
}

public Database_Helper Open() throws SQLiteException {
    dh = new Demo_DBHelper(context);
    sdb = dh.getWritableDatabase();
    return this;
}

public void close() {
    dh.close();
}

public void clearData() {
    sdb.execSQL("DROP TABLE IF EXISTS Contact_Detail");

}

public Cursor getContactDetail() {

    String st = "SELECT * from Contact_Detail";

    Cursor rs_message = sdb.rawQuery(st, null);
    return rs_message;

}

public void add_contact(String name, String phonenumber) {

    ContentValues cv = new ContentValues();
    cv.put("name", name);
    cv.put("phonenumber", phonenumber);
    sdb.insert("Contact_Detail", null, cv);

}

public void removephone(int phonenumber) {

    String str = "SELECT * FROM Contact_Detail where phonenumber='"
            + phonenumber + "' ";
    Cursor rs_message = sdb.rawQuery(str, null);
    if (rs_message.moveToFirst()) {

        String st = "DELETE FROM Contact_Detail where phonenumber='"
                + phonenumber + "' ";
        sdb.execSQL(st);
    }

}

public void update_contactdetail(String phonenumber, String name) {

    ContentValues cv = new ContentValues();
    cv.put("name", "" + name);

    sdb.update("Contact_Detail", cv, "phonenumber=?",
            new String[] { phonenumber });

}

public class DBAdapter {
    //User Master
    public static final String KEY_ROWID = "id";
    public static final String KEY_Email = "email";
    public static final String KEY_PASS = "pass";



    private static final String DATABASE_NAME = "TEST_DB";
    private static final int DATABASE_VIRSION = 1;

    private static final String DATABASE_CREATE = "create table User_Mst(id integer primary key,email text,pass text);";

    private Context context = null;
    private DatabaseHelper DBHelper;
    private SQLiteDatabase db;

    public DBAdapter(Context con) {
    this.context = con;
    DBHelper = new DatabaseHelper(context);
    }
    private class DatabaseHelper extends SQLiteOpenHelper {

    DatabaseHelper(Context context) {
    // TODO Auto-generated constructor stub
    super(context, DATABASE_NAME, null, DATABASE_VIRSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub
    try {
    db.execSQL(DATABASE_CREATE);


    } catch (SQLException e) {
    e.printStackTrace();
    }
    }

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

    db.execSQL("DROP TABLE IF EXISTS User_Mst");



    onCreate(db);
    }
    }

    public DBAdapter open() throws SQLException {
    db = DBHelper.getWritableDatabase();
    return this;
    }
    public void close() {
    DBHelper.close();
    }
    public long insertuser(int i,String mail,String pass) {

    ContentValues init = new ContentValues();
    init.put(KEY_ROWID, i);
    init.put(KEY_Email, mail);
    init.put(KEY_PASS, pass);
    return db.insert("User_Mst", null, init);
    }




    public boolean deleteUser(long rowid) {
    return db.delete("User_Mst", KEY_ROWID + "=" + rowid, null) > 0;
    }



    public Cursor getuser() {
    return db.query("User_Mst", new String[] { KEY_ROWID,KEY_Email,
    KEY_PASS }, null, null, null, null, null);
    }





    public Cursor getUser(long rowid) throws SQLException {
    Cursor mycursor = db.query(true, "User_Mst", new String[] { KEY_ROWID,KEY_Email,KEY_PASS },
    KEY_ROWID + "=" + rowid, null, null,    null, null, null);
    if (mycursor != null) {
    mycursor.moveToFirst();
    }
    return mycursor;
    }

    public boolean updateuser(long rowid,String mail,String pass) {
    ContentValues args = new ContentValues();
    args.put(KEY_Email, mail);
    args.put(KEY_PASS,pass);
    return db.update("User_Mst", args, KEY_ROWID + "=" + rowid, null) > 0;
    }

    }