SQlite與android 的數據交互 (android 項目心得三)

首先把db放在res的下方創一個raw文件夾，裏面用來放db

創一個DbHelper類，實際代碼如下：

    package com.laci.db;  

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

    /** 
     * Created by Laci on 2017/6/25. 
     */  

    public class DbHelper extends SQLiteOpenHelper{  
        /** 
         * 
         * @param context 上下文 
         * @param name 數據庫的名字 
         * @param factory 數據庫工廠，null 
         * @param version  數據庫的版本 
         */  
        public DbHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {  
            super(context, name, factory, version);  
        }  

        @Override  
        public void onCreate(SQLiteDatabase db) {  
        }  

        @Override  
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {  
        }  
    }  

然後再相同的目錄下創一個DbManager類

    package com.laci.db;  

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

    import com.zking.laci.android_project.R;  

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

    /** 
     * Created by Laci on 2017/6/27. 
     */  

    public class DbManager {  
        public static final String DB_NAME = "wenwen.db"; //數據庫名字  
        public static final String PACKAGE_NAME ="com.zking.laci.android_project";//包名  
        public static final String DB_PATH = "/data" + Environment.getDataDirectory().getAbsolutePath() + "/" + PACKAGE_NAME;   //數據庫的絕對路徑( /data/data/com.*.*(package name))  
        private SQLiteDatabase db;  
        private Context context;  

        public DbManager(Context context) {  
            this.context = context;  
        }  

        //對外提供的打開數據庫接口  
        public void openDataBase() {  
            this.db = this.openDataBase(DB_PATH + "/databases");  
        }  

        //獲取打開後的數據庫  
        public SQLiteDatabase getDb() {  
            return this.db;  
        }  

        // 本地打開數據方法  
        private SQLiteDatabase openDataBase(String filePath) {  
            try {  
                File file = new File(filePath);  
                if (!file.exists()) { //判斷文件是否存在  
                    //通過輸入流和輸出流，把數據庫拷貝到"filePath"下  
                    file.mkdir();  
                    File file2=new File(filePath+"/"+DB_NAME);  
                    if (!file2.exists()) {  
                        InputStream is = context.getResources().openRawResource(R.raw.wenwen);//獲取輸入流，使用R.raw.test資源  
                        FileOutputStream fos = new FileOutputStream(file2);  
                        byte[] buffer = new byte[1024];  
                        int readCount;  
                        while ((readCount = is.read(buffer)) > 0) {  
                            fos.write(buffer, 0, readCount);  
                        }  
                        fos.close();  
                        is.close();  
                    }  
                }  
    //打開數據庫  
                SQLiteDatabase db =new DbHelper(context,"wenwen.db",null,2).getWritableDatabase();  
                return db;  
            } catch (Exception e) {  
                e.printStackTrace();  
            }  
            return null;  
        }  

        //關閉數據庫  
        public  void closeDataBase()  
        {  
            if(this.db!=null)  
                db.close();  
        }  
    }  

最後在你第一個開始運行的activity中，寫下以下代碼

DbManager dbManager=new DbManager(getApplicationContext());  
       dbManager.openDataBase();