Question

我第一次使用Ormlite，我正在尝试设置DatabaseHelper以在创建数据库表后插入行。我这样做时出现getWritableDatabase called recursively错误。

这是我的onCreate：

public void onCreate(SQLiteDatabase sqliteDatabase, ConnectionSource connectionSource) {

    try {
        TableUtils.createTable(databaseType, connectionSource, User.class);

        // Add test user
        User test = new User("test", "12345");
        getUserDao().create(test);


    } catch (SQLException e) {
        Log.e(DatabaseHelper.class.getName(), "Unable to create databases", e);
    }
}

Answer 1

这里的问题是@karnage使用的旧版ORMLite在使用onCreate中的DAO时遇到了错误 - 他正在使用的模式。这在版本4.6（10/2010）中得到修复，下载并运行最新版本对他有用。

以下是错误报告：

https://sourceforge.net/tracker/?func=detail&aid=3117883&group_id=297653&atid=1255989

以下是用于跟踪ORMLite的新功能和版本的更改日志文件：

http://ormlite.com/changelog.txt

Answer 2

ORMLite重量轻，用于存储和从数据库中检索数据

I have used ORMLite for storing and retrieveing data from and to database in android below or some simple steps to insert user detail into database through ORM


(1)first we need library for ormlite we can download lib or use dependency in gradle like
dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')  
    compile group: 'com.j256.ormlite', name: 'ormlite-android', version: '4.45'
}


(2) we need to create pojo class User

    public class User {

    @DatabaseField(unique = true,dataType = DataType.STRING)
    String email;
    @DatabaseField(canBeNull = false,dataType = DataType.STRING)
    String pwd; 
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getPwd() {
        return pwd;
    }
    public void setPwd(String pwd) {
        this.pwd = pwd;
    }
}  


(3)We need to create helper class to manage database creation and version management


    public class DatabaseHelper extends OrmLiteSqliteOpenHelper {

	private static final String DATABASE_NAME = "databasename.db";
	private static final int DATABASE_VERSION = 1;
	private Dao<User, Integer> dao = null;
	private RuntimeExceptionDao<User, Integer> runtimeDao = null;
	static  DatabaseHelper databaseHelper;
	public static synchronized DatabaseHelper getInstance(Context context){
		if(databaseHelper== null){
			databaseHelper= new DatabaseHelper(context);
		}
		return databaseHelper;
	}
	public DatabaseHelper(Context context) {
		super(context, DATABASE_NAME, null, DATABASE_VERSION);
	}

	/**
	 * This is called when the database is first created. Usually you should call createTable statements here to create
	 * the tables that will store your data.
	 */
	@Override
	public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) {
		try {
			Log.i(DatabaseHelper.class.getName(), "onCreate");
			TableUtils.createTable(connectionSource, User.class);
		} catch (SQLException e) {
			Log.e(DatabaseHelper.class.getName(), "Can't create database", e);
			throw new RuntimeException(e);
		}
	}

	/**
	 * This is called when your application is upgraded and it has a higher version number. This allows you to adjust
	 * the various data to match the new version number.
	 */
	@Override
	public void onUpgrade(SQLiteDatabase db, ConnectionSource connectionSource, int oldVersion, int newVersion) {

	}

	/**
	 * Returns the Database Access Object (DAO) for our User class. It will create it or just give the cached
	 * value.
	 */
	public synchronized Dao<User, Integer> getDAO() throws SQLException {
		if (dao == null) {
			dao = getDao(User.class);
		}
		return dao;
	}
	
	/**
	 * Returns the RuntimeExceptionDao (Database Access Object) version of a Dao for our User  class. It will
	 * create it or just give the cached value. RuntimeExceptionDao only through RuntimeExceptions.
	 */
	public synchronized RuntimeExceptionDao<User, Integer> getRuntimeDao() {

		if (runtimeDao == null) {
			runtimeDao = getRuntimeExceptionDao(User.class);
		}
		return runtimeDao;
	}



(4) we can insert user into table through DatabaseHelper class from activity or fragment wherever you want

    User user = new User();
    user.setEmail("xyz@gmail.com");
    user.setPwd("1234");



 //this below will insert user into table
   

     public boolean insertUserIntoTable(User user){
        int rowaffected = 0;
        try {
            RuntimeExceptionDao<User, Integer> dao = DatabaseHelper.getInstance(context);
.getRuntimeDao();
            long millis = System.currentTimeMillis();
            rowaffected = dao.create(user);         
        }catch (Exception e){
            e.printStackTrace();
        }finally {

        }
        return (rowaffected == 0) ? false : true;
 }

 

//this will get user from database

    public User getUser(String email,String pwd){

        User user = null;

        QueryBuilder<User, Integer> qb = null;
        try {
            qb =  DatabaseHelper.getInstance(context).getDAO().queryBuilder();
            qb.where().eq("email",email).and().eq("pwd",pwd);
            user = qb.queryForFirst();

        } catch (SQLException e) {

            e.printStackTrace();

        }finally {

        }
        return user;
    }



  //this will update the user in database
 

      public boolean updateUser(User user){
        try {

            Dao<User, Integer> dao = databaseHelper.getDAO();
            UpdateBuilder<User, Integer> updateBuilder = dao.updateBuilder();
            
            updateBuilder.updateColumnValue("email", user.getEmail());
            updateBuilder.updateColumnValue("pwd", user.getPwd());
            updateBuilder.where().eq("email", user.getEmail());
            int row = dao.update(updateBuilder.prepare());

            if(row == 0)
                return false;
            else
                return true;

        }catch (SQLException e){
            e.printStackTrace();
        }finally {
        }
        return false;
    }

Android＆amp; Ormlite：在DatabaseHelper onCreate中插入数据

2 个答案: