ormLite之库表数据迁移(增加字段升级版本号)二

前言

在之前的文章中已经进行过简单的介绍ormlite数据库的简单的操作使用(包含增删改查等...),以及包含了库表简单暴力的升级方法,直接删除旧表,更改版本号,重新创建库表的操作.

今天

应粉丝的要求,来更新一篇此库表的增加字段库表升级的方法介绍,即保留旧表的数据,增加新的字段数据,同时
升级库表版本号的完美操作,废话不多,直接上代码

这是库表锁对应的实体类(这是已经新增的两个字段 age sex)

    @DatabaseTable(tableName = "persons")
    public class Person {
         @DatabaseField(id = true)
         private String name;
         @DatabaseField
         private String password;
         @DatabaseField
         private String age;
         @DatabaseField
         private String sex;

这是库表版本号(我默认原始版本号为7,当然你自己根据实际情况来定)

 public DatabaseHelper(Context context) {
    super(context, TABLE_NAME, null, 7);
}

 @Override
public void onCreate(SQLiteDatabase database, ConnectionSource connectionSource) {
    try {
        TableUtils.createTable(connectionSource, Person.class);
    } catch (SQLException e) {
        e.printStackTrace();
    }

}
 @Override
public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int oldVersion, int newVersion) {

    if(oldVersion < 7){//暂不说明为何要这么判断
        DatabaseUtil.upgradeTable(db,connectionSource,Person.class,DatabaseUtil.OPERATION_TYPE.ADD);
    }
    onCreate(db,connectionSource);
}

工具类(迁移库表数据所需要用到的,直接贴到你的项目中就行)

    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;

     import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
    import com.j256.ormlite.dao.Dao;
    import com.j256.ormlite.support.ConnectionSource;
    import com.j256.ormlite.table.TableUtils;

    import java.sql.SQLException;
    import java.util.HashMap;
    import java.util.Map;


    public class DatabaseHelper extends OrmLiteSqliteOpenHelper {


private static final String TABLE_NAME = "person.db";

private Map<String, Dao> daos = new HashMap<String, Dao>();

public DatabaseHelper(Context context) {
    super(context, TABLE_NAME, null, 7);
}

@Override
public void onCreate(SQLiteDatabase database, ConnectionSource connectionSource) {

    try {
        TableUtils.createTable(connectionSource, Person.class);

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

}

@Override
public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int oldVersion, int newVersion) {

    if(oldVersion < 7){//暂不说明为何要这么判断
        DatabaseUtil.upgradeTable(db,connectionSource,Person.class,DatabaseUtil.OPERATION_TYPE.ADD);
    }
    onCreate(db,connectionSource);
}

private static DatabaseHelper instance;

/**
 * 单例获取该Helper
 *
 * @param context
 * @return
 */
public static synchronized DatabaseHelper getHelper(Context context) {
    context = context.getApplicationContext();
    if (instance == null) {
        synchronized (DatabaseHelper.class) {
            if (instance == null){
                instance=new DatabaseHelper(context);
            }
        }
    }
    return instance;
}

public synchronized Dao getDao(Class clazz)throws SQLException{
    Dao dao=null;
    String className=clazz.getSimpleName();
    if(daos.containsKey(className)){
        dao=daos.get(className);
    }
    if(dao==null){
        dao=super.getDao(clazz);
        daos.put(className,dao);
    }
    return dao;
}

/**
 * 释放资源
 */

@Override
public void close() {
    super.close();

    for(String key:daos.keySet()){
        Dao dao=daos.get(key);
        dao=null;
    }
}

}