Android sd卡读取数据库实例代码

android sd卡读取数据库实例代码

前言：

本文主要给大家讲解如何利用android sd卡读取数据库，提供一些代码如下。先在 manifest 里添加权限：

<span style="font-size:16px;"><uses-permission android:name="android.permission.write_external_storage" /> 
<uses-permission android:name="android.permission.mount_unmount_filesystems" /></span> 

然后在 mainactivity 添加方法

<span style="font-size:16px;">sqlitedatabase db; 
  private final string database_path = android.os.environment 
      .getexternalstoragedirectory().getabsolutepath() + "/vote"; 
  private string database_filename = "db_vote.db"; 
 
 
// 初始化数据库 
  private sqlitedatabase opendatabase() { 
    try { 
      string databasefilename = database_path + "/" + database_filename; 
      file dir = new file(database_path); 
      if (!dir.exists()) 
        dir.mkdir(); 
      if (!(new file(databasefilename)).exists()) { 
        inputstream is = getresources().openrawresource(r.raw.db_vote); 
        fileoutputstream fos = new fileoutputstream(databasefilename); 
        byte[] buffer = new byte[8192]; 
        int count = 0; 
        while ((count = is.read(buffer)) > 0) { 
          fos.write(buffer, 0, count); 
        } 
        fos.close(); 
        is.close(); 
      } 
      db = sqlitedatabase.openorcreatedatabase(databasefilename, null); 
      return db; 
    } catch (exception e) { 
      e.printstacktrace(); 
    } 
    return null; 
  }</span> 

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