ORMLite和GreenDao是Android上最流行的ORM(对象关系映射)框架
现在来简单梳理下ORMLite在Android上的简单使用
本文转自:http://blog.csdn.net/SuperBlueMe/article/details/77019182?locationNum=8&fps=1
1.在官网下载jar包,将这两个jar包放在libs目录下,然后同步工程(也就是将这两个jar包添加进library)
2.创建一个java类(User.java),这个类映射到数据库当中的一张表
@DatabaseTable(tableName = "user")public class User { public User() { } public User(int id, String name, String age, String address) { this.id = id; this.name = name; this.age = age; this.address = address; } @DatabaseField(id = true) private int id; @DatabaseField(columnName = "name") private String name; @DatabaseField(columnName = "age") private String age; @DatabaseField(columnName = "address") private String address; public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; }}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- @DatabaseTable(tableName = “user”) : 代表此类对应于数据库当中的名为user的表
@DatabaseField() : 代表此字段是数据库当中的一个列名
例如:
@DatabaseField(id = true)
private int id; 代表id是此表的主键
@DatabaseField(columnName = “name”)
private String name; 代表name对应于user表中的name字段
更多@DatabaseField()括号中的注解请参考 : ORMLite注解小计
3.新建一个继承自OrmLiteSqliteOpenHelper的类DatabaseHelper,主要用于创建、更新数据库,也可以用来获取数据库操作对象dao
public class DatabaseHelper extends OrmLiteSqliteOpenHelper { private static final String DB_NAME = "ormtest.db"; private static final int DB_VERSION = 1; private Dao<User, Integer> userDao; private DatabaseHelper(Context context) { super(context, DB_NAME, null, DB_VERSION); } private static volatile DatabaseHelper mInstance; /** * 单例模式,获取DatabaseHelper的唯一实例 * * @param context * @return */ public static DatabaseHelper getInstance(Context context) { if (mInstance == null) { synchronized (DatabaseHelper.class) { if (mInstance == null) { mInstance = new DatabaseHelper(context); } } } return mInstance; } /** * 如果还没有这个数据库的时候就会创建数据库,同时创建表格 * * @param sqLiteDatabase * @param connectionSource */ @Override public void onCreate(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource) { try { TableUtils.createTable(connectionSource, User.class); } catch (SQLException e) { e.printStackTrace(); } } /** * 升级数据库 * * @param sqLiteDatabase * @param connectionSource * @param i * @param i1 */ @Override public void onUpgrade(SQLiteDatabase sqLiteDatabase, ConnectionSource connectionSource, int i, int i1) { try { TableUtils.dropTable(connectionSource, User.class, true); onCreate(sqLiteDatabase, connectionSource); } catch (SQLException e) { e.printStackTrace(); } } /** * 释放资源 */ @Override public void close() { super.close(); userDao = null; }}
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 16
- 17
- 18
- 19
- 20
- 21
- 22
- 23
- 24
- 25
- 26
- 27
- 28
- 29
- 30
- 31
- 32
- 33
- 34
- 35
- 36
- 37
- 38
- 39
- 40
- 41
- 42
- 43
- 44
- 45
- 46
- 47
- 48
- 49
- 50
- 51
- 52
- 53
- 54
- 55
- 56
- 57
- 58
- 59
- 60
- 61
- 62
- 63
- 64
- 65
- 66
- 67
- 68
- 69
- 70
- 71
- 72
- 73
- 74
- 75
- 76
4.从DatabaseHelper获取dao对象,用来操作数据库(增删改查)
DatabaseHelper helper = DatabaseHelper.getInstance(this); try { Dao<User, Integer> dao = helper.getDao(User.class); dao.delete(new User()); } catch (SQLException e) { e.printStackTrace(); }
上面只罗列了删除(delete),还有增(create)、改(update)、查(query)的方法
(建议)自己封装一个dao,比如我这里自己封装了一个UserDao,里面包含了数据的增删改查的方法
public class UserDao { private DatabaseHelper mHelper; private Dao<User, Integer> mDao; private static volatile UserDao mUserDao; private UserDao(Context context) { if (mDao == null) { if (mHelper == null) { mHelper = DatabaseHelper.getInstance(context); } try { mDao = mHelper.getDao(User.class); } catch (SQLException e) { e.printStackTrace(); } } } public static UserDao getInstance(Context context) { if (mUserDao == null) { synchronized (UserDao.class) { if (mUserDao == null) { mUserDao = new UserDao(context); } } } return mUserDao; } /** * Create a new row in the database from an object * 创建一条新的记录到数据库中 * * @param user * @return 是否插入成功 */ public boolean insert(User user) { boolean flag = false; try { int i = mDao.create(user); flag = i == 1 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return flag; } /** * 批量插入数据 * * @param user * @return 是否插入成功 */ public boolean insertAll(List<User> user) { boolean flag = false; try { int i = mDao.create(user); flag = i == 1 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return flag; } /** * 删除一条数据 * * @param user * @return */ public boolean delete(User user) { boolean flag = false; try { int rowCount = mDao.delete(user); flag = rowCount == 1 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return flag; } /** * 批量删除 * * @param users * @return */ public boolean deleteAll(List<User> users) { boolean flag = false; try { int rowCount = mDao.delete(users); flag = rowCount == 1 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return flag; } /** * 更新数据 * * @param user * @return */ public boolean update(User user) { boolean flag = false; try { int rowCount = mDao.update(user); flag = rowCount == 1 ? true : false; } catch (SQLException e) { e.printStackTrace(); } return flag; } /** * 批量更新 * * @param users * @return */ public boolean updateAll(List<User> users) { boolean flag = true; try { for (User user : users) { int rowCount = mDao.update(user); boolean b = rowCount == 1 ? true : false; if (!b) { flag = false; } } } catch (SQLException e) { e.printStackTrace(); } return flag; } /** * 使用QueryBuilder查询 */ public List<User> query() { QueryBuilder<User, Integer> builder = mDao.queryBuilder(); Where<User, Integer> where = builder.where(); try { where.and(where.eq("name", "张三"), where.ge("age", 20)); where.and(where.eq("name", "张三"), where.ge("age", 20)).or().eq("address", "陕西"); List<User> users = where.query(); return users; } catch (SQLException e) { e.printStackTrace(); } return null; }
}