轉載請標明出處:http://blog.csdn.net/lmj623565791/article/details/39121377
大家在Android項目中或多或少的都會使用數據庫,爲了提高我們的開發效率,當然少不了數據庫ORM框架了,尤其是某些數據庫操作特別頻繁的app;本篇博客將詳細介紹ORMLite的簡易用法。
下面開始介紹ORMLite的入門用法~
1、下載 ORMLite Jar
首先去ORMLite官網下載jar包,對於Android爲:ormlite-android-4.48.jar 和 ormlite-core-4.48.jar ;
ps:訪問不了的朋友,文章末尾會把jar、源碼、doc與本篇博客例子一起打包提供給大家下載。
2、配置Bean類
有了jar,我們直接新建一個項目爲:zhy_ormlite,然後把jar拷貝到libs下。
然後新建一個包:com.zhy.zhy_ormlite.bean專門用於存放項目中的Bean,首先新建一個User.java
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package com.zhy.zhy_ormlite.bean;
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import com.j256.ormlite.field.DatabaseField;
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import com.j256.ormlite.table.DatabaseTable;
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@DatabaseTable(tableName = "tb_user")
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public class User
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{
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@DatabaseField(generatedId = true)
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private int id;
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@DatabaseField(columnName = "name")
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private String name;
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@DatabaseField(columnName = "desc")
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private String desc;
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public User()
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{
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}
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public User(String name, String desc)
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{
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this.name = name;
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this.desc = desc;
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}
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public int getId()
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{
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return id;
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}
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public void setId(int id)
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{
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this.id = id;
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}
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public String getName()
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{
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return name;
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}
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public void setName(String name)
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{
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this.name = name;
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}
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public String getDesc()
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{
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return desc;
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}
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public void setDesc(String desc)
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{
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this.desc = desc;
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}
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}
首先在User類上添加@DatabaseTable(tableName = "tb_user"),標明這是數據庫中的一張表,標明爲tb_user
然後分別在屬性上添加@DatabaseField(columnName = "name") ,columnName的值爲該字段在數據中的列名
@DatabaseField(generatedId = true) ,generatedId 表示id爲主鍵且自動生成
3、編寫DAO類
原生的數據庫操作,需要繼承SQLiteOpenHelper,這裏我們需要繼承OrmLiteSqliteOpenHelper,看代碼:
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package com.zhy.zhy_ormlite.db;
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import java.sql.SQLException;
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import android.content.Context;
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import android.database.sqlite.SQLiteDatabase;
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import com.j256.ormlite.android.apptools.OrmLiteSqliteOpenHelper;
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import com.j256.ormlite.dao.Dao;
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import com.j256.ormlite.support.ConnectionSource;
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import com.j256.ormlite.table.TableUtils;
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import com.zhy.zhy_ormlite.bean.User;
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public class DatabaseHelper extends OrmLiteSqliteOpenHelper
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{
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private static final String TABLE_NAME = "sqlite-test.db";
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private Dao<User, Integer> userDao;
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private DatabaseHelper(Context context)
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{
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super(context, TABLE_NAME, null, 2);
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}
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@Override
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public void onCreate(SQLiteDatabase database,
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ConnectionSource connectionSource)
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{
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try
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{
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TableUtils.createTable(connectionSource, User.class);
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} catch (SQLException e)
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{
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e.printStackTrace();
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}
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}
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@Override
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public void onUpgrade(SQLiteDatabase database,
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ConnectionSource connectionSource, int oldVersion, int newVersion)
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{
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try
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{
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TableUtils.dropTable(connectionSource, User.class, true);
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onCreate(database, connectionSource);
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} catch (SQLException e)
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{
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e.printStackTrace();
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}
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}
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private static DatabaseHelper instance;
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public static synchronized DatabaseHelper getHelper(Context context)
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{
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if (instance == null)
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{
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synchronized (DatabaseHelper.class)
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{
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if (instance == null)
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instance = new DatabaseHelper(context);
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}
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}
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return instance;
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}
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public Dao<User, Integer> getUserDao() throws SQLException
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{
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if (userDao == null)
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{
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userDao = getDao(User.class);
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}
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return userDao;
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}
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@Override
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public void close()
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{
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super.close();
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userDao = null;
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}
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}
這裏我們需要繼承OrmLiteSqliteOpenHelper,其實就是間接繼承了SQLiteOpenHelper
然後需要實現兩個方法:
1、onCreate(SQLiteDatabase database,ConnectionSource connectionSource)
創建表,我們直接使用ormlite提供的TableUtils.createTable(connectionSource, User.class);進行創建~
2、onUpgrade(SQLiteDatabase database, ConnectionSource connectionSource, int oldVersion, int newVersion)
更新表,使用ormlite提供的TableUtils.dropTable(connectionSource, User.class, true);進行刪除操作~
刪除完成後,別忘了,創建操作:onCreate(database, connectionSource);
然後使用單例公佈出一個創建實例的方法,getHelper用於獲取我們的help實例;
最後我們可能會有很多表嘛,每個表一般我們都會單獨寫個Dao用於操作,這裏爲了簡單我並沒有抽取出來,直接寫在helper中:
比如UserDao的獲取:
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public Dao<User, Integer> getUserDao() throws SQLException
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{
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if (userDao == null)
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{
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userDao = getDao(User.class);
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}
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return userDao;
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}
然後通過獲取到的Dao就可以進行User的一些常用的操作了。
4、測試
最後是測試,我們直接創建了一個測試類進行測試~~~
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package com.zhy.zhy_ormlite.test;
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import java.sql.SQLException;
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import java.util.List;
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import com.zhy.zhy_ormlite.bean.User;
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import com.zhy.zhy_ormlite.db.DatabaseHelper;
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import android.test.AndroidTestCase;
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import android.util.Log;
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public class OrmLiteDbTest extends AndroidTestCase
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{
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public void testAddUser()
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{
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User u1 = new User("zhy", "2B青年");
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DatabaseHelper helper = DatabaseHelper.getHelper(getContext());
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try
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{
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helper.getUserDao().create(u1);
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u1 = new User("zhy2", "2B青年");
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helper.getUserDao().create(u1);
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u1 = new User("zhy3", "2B青年");
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helper.getUserDao().create(u1);
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u1 = new User("zhy4", "2B青年");
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helper.getUserDao().create(u1);
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u1 = new User("zhy5", "2B青年");
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helper.getUserDao().create(u1);
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u1 = new User("zhy6", "2B青年");
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helper.getUserDao().create(u1);
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testList();
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} catch (SQLException e)
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{
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e.printStackTrace();
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}
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}
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public void testDeleteUser()
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{
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DatabaseHelper helper = DatabaseHelper.getHelper(getContext());
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try
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{
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helper.getUserDao().deleteById(2);
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} catch (SQLException e)
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{
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e.printStackTrace();
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}
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}
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public void testUpdateUser()
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{
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DatabaseHelper helper = DatabaseHelper.getHelper(getContext());
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try
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{
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User u1 = new User("zhy-android", "2B青年");
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u1.setId(3);
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helper.getUserDao().update(u1);
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} catch (SQLException e)
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{
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e.printStackTrace();
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}
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}
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public void testList()
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{
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DatabaseHelper helper = DatabaseHelper.getHelper(getContext());
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try
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{
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User u1 = new User("zhy-android", "2B青年");
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u1.setId(2);
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List<User> users = helper.getUserDao().queryForAll();
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Log.e("TAG", users.toString());
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} catch (SQLException e)
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{
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e.printStackTrace();
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}
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}
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}
簡單測試了下CURD,使用AndroidTestCase記得配置下環境~~~
用起來是不是還是非常方便的,不過還是建議大家例如User的數據庫操作,單獨抽取出來爲UserDao,如下:
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package com.zhy.zhy_ormlite.db;
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import java.sql.SQLException;
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import android.content.Context;
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import com.zhy.zhy_ormlite.bean.User;
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public class UserDao
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{
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private Context context;
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public UserDao(Context context)
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{
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this.context = context;
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}
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public void add(User user)
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{
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try
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{
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DatabaseHelper.getHelper(context).getUserDao().create(user);
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} catch (SQLException e)
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{
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}
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}
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}
注:ORMLite還提供了一些基類ORMLiteBaseActivity,ORMLiteBaseService之類的,便於數據庫操作的,這裏不做考慮,畢竟項目中很大可能自己也需要繼承自己的BaseActvity之類的。
上面簡單介紹瞭如何使用ORMLite框架,Android
快速開發系列 ORMLite 框架的使用 將對其用法進行深入的介紹。
源碼點擊下載