Android菜鸟成长记12 -- ORMLite的简单使用

　　在我们的开发中，为了提高开发效率，我们一般都会使用到框架，ormilte则是我们必不可少的数据库框架。

　　对于ORMLite我也是今天才刚刚接触，我们先从一个简单的项目来了解它吧。

ORMLite jar

　　要想使用ormlite，我们要先下载其jar包。

　　下载方法：

　　　　我们可以到官网去下载：http://ormlite.com/releases/

　　　　下载的时候，我们要下载一个core的jar和android的jar，本人用的是ormlite-android-5.0.jar和ormlite-core-5.0.jar

 　　　　然后把我们下载好的jar放在我项目中的lib下，然后加载到项目中即可

　　　

编写Bean类

package com.example.bean;

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

@DatabaseTable(tableName="t_student")
public class student {

    //generatedId表示该字段名为主键，却自增长
    @DatabaseField(generatedId=true)
    private int stuId;
    @DatabaseField(columnName="stuName")
    private String stuName;
    @DatabaseField(columnName="age")
    private int age;
    public int getStuId() {
        return stuId;
    }
    public void setStuId(int stuId) {
        this.stuId = stuId;
    }
    public String getStuName() {
        return stuName;
    }
    public void setStuName(String stuName) {
        this.stuName = stuName;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    
}

 @DatabaseTable(tableName = "tb_user")，标明这是数据库中的一张表

@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

编写ORMilte的dao包

package com.example.ormlitetest;

import java.sql.SQLException;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.util.Log;

import com.example.bean.student;
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 DataBaseHelp extends OrmLiteSqliteOpenHelper{

    private static final int version = 1;
    private static final String DB_NAME = "text_data.db";
    //每张表对应一个
    private Dao<student,Integer> studao ;
    
    public Dao<student,Integer> getDao() throws SQLException{
        if(studao == null){
            studao = getDao(student.class);
        }
        return studao;
    }
    
    public DataBaseHelp(Context context) {
        super(context, DB_NAME, null, version);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db, ConnectionSource connectionSource) {
        try {
            TableUtils.createTable(connectionSource, student.class);
            Log.i("tag", "创建数据库success");
        } catch (Exception e) {
            Log.i("tag", "错误");
        }
        
    }

    @Override
    public void onUpgrade(SQLiteDatabase arg0, ConnectionSource arg1, int arg2,
            int arg3) {
        // TODO Auto-generated method stub
        
    }
    
    
    @Override
    public void close() {
        // TODO Auto-generated method stub
        super.close();
        studao = 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);

MainActivity类通用数据库

package com.example.ormlitetest;

import java.sql.SQLException;
import java.util.*;

import com.example.bean.student;

import android.app.Activity;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends Activity {

    
    private SQLiteDatabase db;
    private ListView lv;
    private List<student> stulist = new ArrayList<student>();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        DataBaseHelp help = new DataBaseHelp(MainActivity.this);
        
        for (int i = 0; i < 100; i++) {
            student s = new student();
            s.setStuName("好无聊" + i);
            s.setAge(i);
            try {
                help.getDao().create(s);
            } catch (SQLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        try {
            stulist = help.getDao().queryForAll();
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        lv = (ListView) findViewById(R.id.listView1);
        lv.setAdapter(new BaseAdapter() {

            public View getView(int position, View convertView, ViewGroup parent) {
                View view = null;
                if (convertView == null) {
                    Log.i("info:", "没有缓存，重新生成" + position);
                    LayoutInflater inflater = MainActivity.this
                            .getLayoutInflater();
                    // 因为getView()返回的对象，adapter会自动赋给ListView
                    view = inflater
                            .inflate(R.layout.list_item, null);
                } else {
                    Log.i("info:", "有缓存，不需要重新生成" + position);
                    view = convertView;
                }
                student s = stulist.get(position);

                TextView tv_userName = (TextView) view
                        .findViewById(R.id.tv_stuName);
                tv_userName.setText(s.getStuName());
                tv_userName.setTextSize(15);

                TextView tv_lastMessage = (TextView) view
                        .findViewById(R.id.tv_age);
                tv_lastMessage.setText(s.getAge()+"");
                tv_lastMessage.setTextSize(12);

                return view;
            }

            @Override
            public long getItemId(int arg0) {
                // TODO Auto-generated method stub
                return 0;
            }

            @Override
            public Object getItem(int arg0) {
                // TODO Auto-generated method stub
                return null;
            }

            @Override
            public int getCount() {
                // TODO Auto-generated method stub
                return stulist.size();
            }
        });
        help.close();
    }

}

然后我们运行一下程序看一下

好了， 这就是本人对于ORMLite的初步了解。