SQlite与android 的数据交互 (android 项目心得三)

首先把db放在res的下方创一个raw文件夹，里面用来放db

创一个DbHelper类，实际代码如下：

    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 数据库的名字          * @param factory 数据库工厂，null          * @param version  数据库的版本          */          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) {          }      }

然后再相同的目录下创一个DbManager类

    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"; //数据库名字          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;   //数据库的绝对路径( /data/data/com.*.*(package name))          private SQLiteDatabase db;          private Context context;          public DbManager(Context context) {              this.context = context;          }          //对外提供的打开数据库接口          public void openDataBase() {              this.db = this.openDataBase(DB_PATH + "/databases");          }          //获取打开后的数据库          public SQLiteDatabase getDb() {              return this.db;          }          // 本地打开数据方法          private SQLiteDatabase openDataBase(String filePath) {              try {                  File file = new File(filePath);                  if (!file.exists()) { //判断文件是否存在                      //通过输入流和输出流，把数据库拷贝到"filePath"下                      file.mkdir();                      File file2=new File(filePath+"/"+DB_NAME);                      if (!file2.exists()) {                          InputStream is = context.getResources().openRawResource(R.raw.wenwen);//获取输入流，使用R.raw.test资源                          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();                      }                  }      //打开数据库                  SQLiteDatabase db =new DbHelper(context,"wenwen.db",null,2).getWritableDatabase();                  return db;              } catch (Exception e) {                  e.printStackTrace();              }              return null;          }          //关闭数据库          public  void closeDataBase()          {              if(this.db!=null)                  db.close();          }      }

最后在你第一个开始运行的activity中，写下以下代码

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

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