sqlite与android交互 (封装)

    学android已经有大概一周时间了吧 ，总感觉自己基础不怎么好，只能通过一点一点积累着敲来巩固平常的知识，有的时候就先不封装的敲一遍，再封装上，有些语句真的记不住，虽然知道他是什么意思，于是乎就反复的敲着，加油吧！少年，下面进入正题吧

　　DBConn.java类 主要是将raw写入到DDMS里的data/data/xxx包/下，代码如下：

　　

package com.tp.soft.util;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;

import com.example.dbcity.R;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.os.Environment;

public class DBConn {
    private static String DB_NAME = "test.db";
    private static String PACKAGE = "com.example.dbcity";
    private static String PATH = "/data" +
                Environment.getDataDirectory().getPath()+
                File.separator + PACKAGE;
    private Context context;
    private SQLiteDatabase database;
    public DBConn(Context context){
        this.context = context;
    }
    
    public static final DBConn getInstance(Context context){
        DBConn conn = new DBConn(context);
        return conn;
    }
    public SQLiteDatabase getDb(){
        database = openDB(PATH + File.separator + DB_NAME);
        return database;
    }
    
    public SQLiteDatabase openDB(String dbFile){
        try{
            if(!isExitFile(dbFile)){
                InputStream is = context.getResources().openRawResource(R.raw.test);
                FileOutputStream fos = new FileOutputStream(dbFile);
                byte[] buffer = new byte[1024];
                int len = -1;
                while((len = is.read(buffer)) != -1){
                    fos.write(buffer, 0, len);
                }
                is.close();
                fos.close();
            }
            
            database = SQLiteDatabase.openOrCreateDatabase(dbFile, null);
            return database;
        }catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    
    public boolean isExitFile(String path){
        File file = new File(path);
        return file.exists();
    }
}

DBManage.java主要是对数据库的封装，目前只做了个查询，待后期完善吧，代码如下：

package com.tp.soft.util;

import java.util.ArrayList;
import java.util.List;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

public class DBManage {
    private SQLiteDatabase db;
    
    public DBManage(Context context) {
        DBConn conn = DBConn.getInstance(context);
        db = conn.getDb();
    }

    public List<String> queryData(String sql, String[] selectionArgs, String property){
        Cursor cursor = null;
        List<String> list = new ArrayList<String>();
        try{
            cursor = db.rawQuery(sql, selectionArgs);
            while(cursor.moveToNext()){
                String str = cursor.getString(cursor.getColumnIndex(property));
                list.add(str);
            }
        }catch (Exception e) {
            e.printStackTrace();
        }finally{
            if(null != cursor){
                cursor.close();
            }
        }
        return list;
    }
    
}

主入口就是一个下拉列表的显示，然后就是调用sqlite数据库了，部分代码如下：

proSelect = (Spinner) findViewById(R.id.proSelect);
        DBManage dbManage = new DBManage(this);
        List<String> proList = dbManage.queryData("select * from au_user", null, "username");
        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_gallery_item, proList);
        proSelect.setAdapter(arrayAdapter);

总结一句话，其实代码敲多了 才去想怎么敲，而不是一点都没敲就去想如何将语句敲到最好 我觉得这个是不可能的，菜鸟自学路程。。。