Android—Ormlite框架简单的操作数据库

大家在Android项目中或多或少的都会使用数据库，为了提高我们的开发效率，当然少不了数据库ORM框架了，尤其是某些数据库操作特别频繁的app；本篇博客将详细介绍ORMLite的简易用法。

下面开始介绍ORMLite的入门用法~

1、下载 ORMLite Jar

首先去ORMLite官网下载jar包，对于Android为：ormlite-android-5.0.jar 和 ormlite-core-5.0.jar ；

ps:访问不了的朋友，文章末尾会把jar、源码、doc与本篇博客例子一起打包提供给大家下载。

2、配置Bean类

有了jar,我们直接新建一个项目为：OrmliteDemo，然后把jar拷贝到libs下。

然后新建一个包：com.my.bean专门用于存放项目中的Bean，首先新建一个Usera.Java

Users:

 package com.my.bean;

 import com.j256.ormlite.field.DatabaseField;
 import com.j256.ormlite.table.DatabaseTable;

 @DatabaseTable(tableName="tb_users")
 public class Users {
     @DatabaseField(generatedId=true)
     private int id;
     @DatabaseField(columnName="name")
     private String name;
     @DatabaseField(columnName="desc")
     private String desc;
     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 getDesc() {
         return desc;
     }
     public void setDesc(String desc) {
         this.desc = desc;
     }
     public Users( String name, String desc) {
         super();
         this.name = name;
         this.desc = desc;
     }
     public Users() {
         super();
         // TODO Auto-generated constructor stub
     }

 }

首先在User类上添加@DatabaseTable(tableName = "tb_user")，标明这是数据库中的一张表，标明为tb_users

然后分别在属性上添加@DatabaseField(columnName = "name") ，columnName的值为该字段在数据中的列名

@DatabaseField(generatedId = true) ，generatedId 表示id为主键且自动生成

3、编写DAO类

原生的数据库操作，需要继承SQLiteOpenHelper，这里我们需要继承OrmLiteSqliteOpenHelper

DatabaseHelper:

 package com.my.db;

 import java.sql.SQLException;

 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 com.my.bean.Users;

 public class DatabaseHelper extends OrmLiteSqliteOpenHelper{
     private static final String TABLE_NAME = "users.db";
     /**
      * usersDao，每张表对应一个
      */
     private Dao<Users,Integer> usersDao ;

     private static DatabaseHelper instance;
     public DatabaseHelper(Context context) {
         super(context, TABLE_NAME, null, 1);
         // TODO Auto-generated constructor stub
     }

     @Override
     public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {
         // TODO Auto-generated method stub
         try{
             TableUtils.createTable(arg1, Users.class);
         }catch(Exception e){
             e.printStackTrace();
         }
     }

     @Override
     public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2,
             int arg3) {
         try
         {
             TableUtils.dropTable(connectionSource, Users.class, true);
             onCreate(arg0, connectionSource);
         } catch (SQLException e)
         {
             e.printStackTrace();
         }  

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

     /**
      * 获得userDao
      * @throws SQLException
      */
     public Dao<Users,Integer> getUsersDao() throws SQLException{
         if(usersDao == null){
             usersDao = getDao(Users.class);
         }
         return usersDao;
     }

     /**
      * 释放资源
      */

     @Override
     public void close() {
         // TODO Auto-generated method stub
         super.close();
         usersDao = null;
     }
 }

这里我们需要继承OrmLiteSqliteOpenHelper，其实就是间接继承了SQLiteOpenHelper

然后需要实现两个方法：

1、onCreate(SQLiteDatabase database,ConnectionSource connectionSource)

创建表，我们直接使用ormlite提供的TableUtils.createTable(connectionSource, User.class);进行创建~

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);进行删除操作~

删除完成后，别忘了，创建操作：onCreate(database, connectionSource);

然后使用单例公布出一个创建实例的方法，getHelper用于获取我们的help实例；

4、显示在Activity

　　MainActivity:

package com.example.ormlitedemo;

import java.util.List;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TableLayout;
import android.widget.TableRow;
import android.widget.TableRow.LayoutParams;
import android.widget.TextView;

import com.j256.ormlite.dao.Dao;
import com.my.bean.Users;
import com.my.db.DatabaseHelper;

public class MainActivity extends Activity {
    private Dao<Users,Integer> usersDao;
    private Context context;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        context = this;
        //新建一个表格布局
        TableLayout tblay = new TableLayout(this);
        //给该Activity设置布局
        setContentView(tblay,new TableLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT));
        //插入数据
        init();
        try{

            //取出数据
            List<Users> users = getList();

            //遍历集合
            for (Users u : users) {
                //创建一行
                TableRow tr = new TableRow(this);
                //新建文本视图
                TextView v1 = new TextView(this);
                TextView v2 = new TextView(this);
                TextView v3 = new TextView(this);
                v1.setText(u.getId()+"");
                v2.setText(u.getName());
                v3.setText(u.getDesc());
                //把文本视图添加到TableRow中
                tr.addView(v1,new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 1));
                tr.addView(v2,new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 1));
                tr.addView(v3,new TableRow.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT, 1));
                //把TableRow添加到TableLayout中
                tblay.addView(tr);
            }

        }catch(Exception e){
            e.printStackTrace();
        }
    }
     //插入数据
    public void init(){
        DatabaseHelper helper = DatabaseHelper.getHelper(context);
        try{
            Users u1 = new Users("zhy","2b铅笔");
            usersDao = helper.getUsersDao();
            usersDao.create(u1);
            u1 = new Users("zhy2", "2b铅笔");
            usersDao.create(u1);
            u1 = new Users("zhy3", "2b铅笔");
            usersDao.create(u1);
            u1 = new Users("zhy4", "2b铅笔");
            usersDao.create(u1);
            u1 = new Users("zhy5", "2b铅笔");
            usersDao.create(u1);
            u1 = new Users("zhy6", "2b铅笔");
            usersDao.create(u1);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
    //查询所有操作
    public List<Users> getList(){
        DatabaseHelper helper = DatabaseHelper.getHelper(context);
        List<Users> users = null;
        try{
            users = helper.getUsersDao().queryForAll();

        }catch(Exception e){
            e.printStackTrace();
        }
        return users;
    }

    //删除操作
    public void DeleteUser(){
        DatabaseHelper helper = DatabaseHelper.getHelper(context);
        try{
            helper.getUsersDao().deleteById(2);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
        //更新操作
    public void UpdateUser(){
        DatabaseHelper helper = DatabaseHelper.getHelper(context);
        try{
            Users u1 = new Users("lisi", "4b铅笔");
            u1.setId(3);
            helper.getUsersDao().update(u1);
        }catch(Exception e){
            e.printStackTrace();
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

运行结果如下：

好了，Ormlite的简单操作就说这里了。。。。希望对大家有用，不喜勿喷