Android上ORMLite的配置和简单使用

来源：互联网发布：java valueof 编辑：程序博客网时间：2024/06/05 19:13

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

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)
这里写图片描述

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;    }}

@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 {            //创建表            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;    }}

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());//删除数据        } 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 {            //插入或者更新的行数,单条插入成功就是1            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 {            //插入或者更新的行数,单条插入成功就是1            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 {            //相当于:select * from user where name = '张三' and age > 20            where.and(where.eq("name", "张三"), where.ge("age", 20));            //下面这条语句相当于:select * from user where (name = '张三' and age > 20 ) or address = '陕西'            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;    }}

基本的使用就介绍到此,如果希望更加深入的了解,建议移步官网

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