关于androidORMLite的一些总结

关于androidORMLite的一些总结

ORMLite是一种对象关系映射（Object-Relational Mapping， 简称ORM）工具，可用于读写数据。ORMLite是一个框架，更佳方便对多数据进行操作，特别是对于那些对SQL语句不熟悉的人

使用：

1. 下载 ORMLite Jar
   首先去ORMLite官网下载jar包，对于Android为：ormlite-android-4.48.jar 和 ormlite-core-4.48.jar ；
2. 创建Bean

User.java

/*
* 当定义表时，第一个建议便是使用final变量定义数据库表名和列名，
* 该方法可以简化代码的维护工作，不过本例并没用使用*/
@DatabaseTable(tableName = "tb_user") //@DatabaseTable：标明这是数据库的一张表
public class User {/*@DatabaseField：标明这是表中的字段columnName: 为该字段在数据中的列名generatedId：表示id为自增长*/@DatabaseField(generatedId = true)private int id;@DatabaseField(columnName = "name")private String name;@DatabaseField(columnName = "desc")private String desc;/*ORMLite需要用到无参构造方法* 当ORMLite需要创建User类时会使用到无参数的构造方法，* 并通过反射机制设置成员变量，也可以使用setter方法设置成员变量*/public User() {}public User(String name, String desc) {this.name = name;this.desc = desc;}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 getDesc() {return desc;}public void setDesc(String desc) {this.desc = desc;}
}

1. 创建数据库
   原生的数据库操作，需要继承SQLiteOpenHelper，这里我们需要继承OrmLiteSqliteOpenHelper

2. public class DatabaseHelper extends OrmLiteSqliteOpenHelper {//数据库文件的名称private static final String TABLE_NAME = "sqlit-test.db";/*userDao , 每张表对应一个*/private Dao<User, Integer> userDao;private DatabaseHelper(Context context) {super(context, TABLE_NAME, null, 2);}@Overridepublic void onCreate(SQLiteDatabase sqLiteDatabase,ConnectionSource connectionSource) {try{//创建表createTable(connectionSource, User.class);}catch (SQLException e){e.printStackTrace();}}@Overridepublic void onUpgrade(SQLiteDatabase sqLiteDatabase,ConnectionSource connectionSource, int i, int i1) {try{dropTable(connectionSource, User.class, true);onCreate(sqLiteDatabase, connectionSource);}catch (SQLException e){e.printStackTrace();}}private static DatabaseHelper instance;/** 单例获取该Helper*/public static synchronized DatabaseHelper getHelper(Context context) {if (instance == null){synchronized (DatabaseHelper.class){if (instance == null){instance = new DatabaseHelper(context);}}}return instance;}/** 获得userDao*/public Dao<User, Integer> getUserDao() throws SQLException {if (userDao == null){userDao = getDao(User.class);}return userDao;}/** 释放资源*/public void close(){super.close();userDao=null;}
   }

   这里我们需要继承OrmLiteSqliteOpenHelper，其实就是间接继承了SQLiteOpenHelper

   然后需要实现两个方法：

• onCreate(SQLiteDatabase database,ConnectionSource connectionSource)

创建表，我们直接使用ORMLite提供的TableUtils.createTable(connectionSource, User.class);进行创建

• onUpgrade(SQLiteDatabase database, ConnectionSource connectionSource, int oldVersion, int newVersion)

• 数据库的增删改查

//增加数据public void testAddUser(){User u1 = new User("zhy", "2B青年");DatabaseHelper helper = DatabaseHelper.getHelper(getContext());try{helper.getUserDao().create(u1);u1 = new User("zhy2", "2B青年");helper.getUserDao().create(u1);u1 = new User("zhy3", "2B青年");helper.getUserDao().create(u1);u1 = new User("zhy4", "2B青年");helper.getUserDao().create(u1);u1 = new User("zhy5", "2B青年");helper.getUserDao().create(u1);u1 = new User("zhy6", "2B青年");helper.getUserDao().create(u1);testList();}catch (SQLException e){e.printStackTrace();}}//删除数据public void testDeleteUser(){DatabaseHelper helper = DatabaseHelper.getHelper(getContext());try{helper.getUserDao().deleteById(2);}catch (SQLException e){e.printStackTrace();}}//更新数据public void testUpdateUser(){DatabaseHelper helper = DatabaseHelper.getHelper(getContext());try{User u1 = new User("zhy-android", "2B青年");u1.setId(3);helper.getUserDao().update(u1);}catch (SQLException e){e.printStackTrace();}}//查询数据public void testList(){DatabaseHelper helper = DatabaseHelper.getHelper(getContext());try {User u1 = new User("zhy-android", "2B青年");u1.setId(2);List<User> users = helper.getUserDao().queryForAll();Log.e("TAG", users.toString());}catch (SQLException e){e.printStackTrace();}}