Android学习之操作SQLite

基本上写程序总会要和数据库打交道，最近学习android,熟悉了下sqlite,额，也不能说熟悉把，就是大体上看了下，晓得怎么用了，把我写的贴上来。

关于Sqlite数据库这里就不多少了，谷歌下网上一大堆。

 

package org.leepood.sqlite;

 import android.content.Context;
 import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
//自定义的数据库通用访问类，简单地写了下创建，插入，查询数据库
public class DBAdapter  {
    private Context context;
    private SQLiteDatabase database;
    public DBAdapter(Context context)
    {
        this.context=context;
    }
    //打开或者创建数据库
    public void OpenOrCreateDB(String DBName)
    {
        database=context.openOrCreateDatabase(DBName,0, null);
        
    }
    //创建表结构
    //参数tablaename表示表名
    //fields表示字段
    public void CreateTable(String tablename,Object[] fields)
    {
        StringBuffer sb=new StringBuffer();
        String allfields=new String();
        //构造字段字符串，android的表里必须有个_id字段且为主键，sqlite会忽略其他字段的类型
        for(Object obj :fields)
        {
            allfields+=obj.toString()+",";
        }
        allfields=allfields.substring(0, allfields.length()-1);
        sb.append("Create table if not exists ").append(tablename).append("(_id integer primary key,").append(allfields).append(")");
        //Log.i("sql", sb.toString());
        database.execSQL(sb.toString());
    }
    //插入数据，fields和values长度必须相同，字段和字段的值一一对应
    public void Insert(String tablename,Object[] fields,Object[] values)
    {
        if(fields.length==values.length)
        {
            StringBuffer sb=new StringBuffer();
            String allfields=new String();
            String allvalues=new String();
            for(int i=0;i<fields.length;i++)
            {
                allfields+=fields[i].toString()+",";
                allvalues+="\""+values[i].toString()+"\""+",";
            }
            allfields=allfields.substring(0,allfields.length()-1);
            allvalues=allvalues.substring(0,allvalues.length()-1);
            sb.append("insert into ").append(tablename).append("(").append(allfields).append(") ").append("values(")
                .append(allvalues).append(")");
            //Log.i("sqlinsert", sb.toString());
            database.execSQL(sb.toString());
            
            
        }
    }
    //查询数据，返回cursor
    public Cursor getCursor(String tablename,String condition,Object[] fields) throws Exception
    {
        
        StringBuffer sb=new StringBuffer();
        String allfields =new String();
        if(fields==null)
        {
            allfields="*";
        }
        else
        {
            for(int i=0;i<fields.length;i++)
            {
            allfields+=fields[i].toString()+",";    
            }
        allfields=allfields.substring(0,allfields.length()-1);
        }
        
        sb.append("select ").append(allfields).append(" from ").append(tablename).append(" where ").append(condition);
        Log.i("sqlquery", sb.toString());
        return database.rawQuery(sb.toString(), null);
        
    }

}

下面的代码是调用这个类来操作数据库:

 

package org.leepood.sqlite;

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;

public class MainActive extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
       DBAdapter dbadapter= new DBAdapter(this.getApplicationContext());
       dbadapter.OpenOrCreateDB("lacus");
17
18
       dbadapter.CreateTable("leepood", new Object[]{"name","age","sex"});
       dbadapter.Insert("leepood", new Object[]{"name","age","sex"}, new Object[]{"leepood","13","男"});
       dbadapter.Insert("leepood", new Object[]{"name","age","sex"}, new Object[]{"iagyje","132","男"});
       dbadapter.Insert("leepood", new Object[]{"name","age","sex"}, new Object[]{"lee","33","男"});
       dbadapter.Insert("leepood", new Object[]{"name","age","sex"}, new Object[]{"sunlinyu","23","男"});
       try {
        Cursor cursor=dbadapter.getCursor("leepood", "1=1", null);
        while(cursor.moveToNext())
        {
            Log.i("cursor_id", Integer.toString(cursor.getInt(0)));
            Log.i("cursor_name",cursor.getString(1));
        }
        //Log.i("coloumncount", Integer.toString(cursor.getColumnCount()));
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
        
    }
}

最后看下导出来的数据库:

运行效果: