上一篇已经对ORMLite框架做了简单的介绍：Android数据库框架-----ORMLite 的基本用法~~本篇将介绍项目可能会使用到的一些用法，也为我们的使用ORMLite框架总结出一个较合理的用法。

本文主要介绍两表相互关联的使用，如同外键，相互的查询功能；

创建 User和Article类

@DatabaseTable(tableName = "tb_user")
public class User 
{
    @DatabaseField(generatedId = true)
    private int id;
    @DatabaseField(columnName = "name")
    private String name;
@ForeignCollectionField
private Collection<Article> articles;

public Collection<Article> getArticles()
{
    return articles;
}

public void setArticles(Collection<Article> articles)
{
    this.articles = articles;
}

public User()
{
}

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;
}

@Override
public String toString()
{
    return "User [id=" + id + ", name=" + name + ", articles=" + articles
            + "]";
}

    
      
      
    
  
}

@ForeignCollectionField
private Collection<Article> articles;

每个User关联一个或多个Article，如果我在User中声明一个Collection<Article> articles，我能否在查询User的时候，一并能够获取到articles的值。

@DatabaseTable(tableName = "tb_article")
public class Article
{
    @DatabaseField(generatedId = true)
    private int id;
    @DatabaseField
    private String title;
    @DatabaseField(canBeNull = true, foreign = true, columnName = "user_id", foreignAutoRefresh = true)
    private User user;
public int getId()
{
    return id;
}

public void setId(int id)
{
    this.id = id;
}

public String getTitle()
{
    return title;
}

public void setTitle(String title)
{
    this.title = title;
}

public User getUser()
{
    return user;
}

public void setUser(User user)
{
    this.user = user;
}

@Override
public String toString()
{
    return "Article [id=" + id + ", title=" + title + ", user=" + user
            + "]";
}

    
      
      
    
  
}

在user属性的注解上：@DatabaseField(canBeNull = true, foreign = true, columnName = "user_id", foreignAutoRefresh = true)

添加foreignAutoRefresh =true，这样；当调用queryForId时，拿到Article对象则直接携带了user；

 DatabaseHelpe.java

public class DatabaseHelper extends OrmLiteSqliteOpenHelper
{
    private static final String TABLE_NAME = "sqlite-test.db";
private Map<String, Dao> daos = new HashMap<String, Dao>();

private DatabaseHelper(Context context)
{
    super(context, TABLE_NAME, null, 4);
}

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

@Override
public void onUpgrade(SQLiteDatabase database,
        ConnectionSource connectionSource, int oldVersion, int newVersion)
{
    try
    {
        TableUtils.dropTable(connectionSource, User.class, true);
        TableUtils.dropTable(connectionSource, Article.class, true);
        onCreate(database, connectionSource);
    } catch (SQLException e)
    {
        e.printStackTrace();
    }
}

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;
    }
}

    
      
      
    
  
}

Userdao操作类

public class UserDao
{
    private Context context;
    private Dao<User, Integer> userDaoOpe;
    private DatabaseHelper helper;
public UserDao(Context context)
{
    this.context = context;
    try
    {
        helper = DatabaseHelper.getHelper(context);
        userDaoOpe = helper.getDao(User.class);
    } catch (SQLException e)
    {
        e.printStackTrace();
    }
}

/**
 * 增加一个用户
 * 
 * @param user
 * @throws SQLException
 */
public void add(User user) 
{
    /*//事务操作
    TransactionManager.callInTransaction(helper.getConnectionSource(),
            new Callable&lt;Void&gt;()
            {

                @Override
                public Void call() throws Exception
                {
                    return null;
                }
            });*/
    try
    {
        userDaoOpe.create(user);
    } catch (SQLException e)
    {
        e.printStackTrace();
    }

}

public User get(int id)
{
    try
    {
        return userDaoOpe.queryForId(id);
    } catch (SQLException e)
    {
        e.printStackTrace();
    }
    return null;
}

    
      
      
    
  
}

ArticleDao操作类

public class ArticleDao
{
    private Dao<Article, Integer> articleDaoOpe;
    private DatabaseHelper helper;
@SuppressWarnings("unchecked")
public ArticleDao(Context context)
{
    try
    {
        helper = DatabaseHelper.getHelper(context);
        articleDaoOpe = helper.getDao(Article.class);
    } catch (SQLException e)
    {
        e.printStackTrace();
    }
}

/**
 * 添加一个Article
 * 
 * @param article
 */
public void add(Article article)
{
    try
    {
        articleDaoOpe.create(article);
    } catch (SQLException e)
    {
        e.printStackTrace();
    }
}

/**
 * 通过Id得到一个Article
 * 
 * @param id
 * @return
 */
@SuppressWarnings("unchecked")
public Article getArticleWithUser(int id)
{
    Article article = null;
    try
    {
        article = articleDaoOpe.queryForId(id);
        helper.getDao(User.class).refresh(article.getUser());

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

/**
 * 通过Id得到一篇文章
 * 
 * @param id
 * @return
 */
public Article get(int id)
{
    Article article = null;
    try
    {
        article = articleDaoOpe.queryForId(id);

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

/**
 * 通过UserId获取所有的文章
 * 
 * @param userId
 * @return
 */
public List&lt;Article&gt; listByUserId(int userId)
{
    try
    {
        QueryBuilder&lt;Article, Integer&gt; articleBuilder = articleDaoOpe
                .queryBuilder();
        QueryBuilder userBuilder = helper.getDao(User.class).queryBuilder();
        articleBuilder.join(userBuilder);
        
        
        /*Where&lt;Article, Integer&gt; where = articleBuilder.where();
        where.eq("user_id", 1);
        where.and();
        where.eq("title", "ORMLite数据库");
        
        return where.query();*/
        
        // 或者
         /*return articleDaoOpe.queryBuilder().//
                where().//
                eq("user_id", 1).and().//
                eq("title", "ORMLite数据库").query();*/
        
         //复杂的查询
        /*where.or(
                //
                where.and(//
                        where.eq("user_id", 1), where.eq("name", "xxx")),
                where.and(//
                        where.eq("user_id", 2), where.eq("name", "yyy")));*/

        return articleDaoOpe.queryBuilder().where().eq("user_id", userId)
                .query();
    } catch (SQLException e)
    {
        e.printStackTrace();
    }
    return null;
}

    
      
      
    
  
}

用于where查询，在ArticleDao类中包含的有。更多的用法，去官方文档查看，源码中提供了文档；

提示：运行测试时，要先添加数据，源码未做错误处理 

不足之处请留言指正！有问题的可以给我留言！谢谢！