ormlite 的简单应用

在android开发中还有哪些技术可以方便的操作数据库，我不大清楚，今天学习了一下 ormlite，觉得还不错，非常方便。

ormlite官网下载：http://ormlite.com/releases/

1、引入jar包

2、写实体类

package com.example.aandroidtest;

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

@DatabaseTable
public class User {
	@DatabaseField(generatedId=true)//自增长的主键
	private int id;
	@DatabaseField
	private String userName;
	@DatabaseField
	private String password;
	
	//必须有一个无参的构造函数
	public User() {
		super();
	}
	
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	public String getUserName() {
		return userName;
	}
	public void setUserName(String userName) {
		this.userName = userName;
	}
	public String getPassword() {
		return password;
	}
	public void setPassword(String password) {
		this.password = password;
	}
}

3、创建一个helper类

package com.example.aandroidtest;

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;

public class DBHelper extends OrmLiteSqliteOpenHelper {
	/*一张表对应一个dao*/
	private Dao<User, Integer> userDao;
	
	private final static int DB_VERSION = 1;  
    private static final String DB_NAME = "orm";  
	
	/**构造函数，貌似是必须有的
	 * @param context
	 */
	public DBHelper(Context context) {
		super(context, DB_NAME, null, DB_VERSION);
	}
	
	@Override
	public void onCreate(SQLiteDatabase arg0, ConnectionSource arg1) {
		try {
			TableUtils.createTable(arg1, User.class);
		} catch (SQLException e) {
			e.printStackTrace();
		}
	}

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

	public Dao<User, Integer> getUserDao() throws SQLException {
		if(userDao == null) {
			userDao = getDao(User.class);
		}
		return userDao;
	}
}

4、Activity 继承 OrmLiteBaseActivity ，至此就可以方便的使用了，增删查改。

package com.example.aandroidtest;

import java.sql.SQLException;
import java.util.List;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;
import android.view.Menu;

import com.j256.ormlite.android.apptools.OrmLiteBaseActivity;
import com.j256.ormlite.dao.Dao;

public class MainActivity extends OrmLiteBaseActivity<DBHelper> {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        try {
        	//先获取userDao
			Dao<User, Integer> userDao = this.getHelper().getUserDao();
			
			//增
			User user = new User();
			user.setUserName("qiantu");
			user.setPassword("000000");
			userDao.create(user);
			
			//删
			userDao.deleteById(1);
			
			//查
			String str = "";
			List<User> list = userDao.queryForAll();
//			List<User> list = userDao.queryForEq("id", 2);
			for(User u : list) {
				str += "id="+String.valueOf(u.getId())+"\tusername="
						+u.getUserName()+"\tpassword="+u.getPassword()+"\n";
			}
			//显示dialog查看数据
			new AlertDialog.Builder(this)
				.setTitle("提示")
				.setMessage(str)
				.setNegativeButton("取消", new OnClickListener() {
					@Override
					public void onClick(DialogInterface dialog, int which) {
						
					}
				})
				.show();
			
			//改
			User u = userDao.queryForId(3);
			u.setUserName("我已经该了名字");
			userDao.update(u);
			
		} catch (SQLException 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;
    }
}