保存数据库到本地

// 本地备份
    private void backupDatabaseToSD() {
        AlertDialog.Builder builder = new AlertDialog.Builder(
                SettingActivity.this);
        builder.setTitle("SD卡备份");
        builder.setMessage("备份文件保存在/sdcard/MrBill");
        builder.setPositiveButton("保存", new DialogInterface.OnClickListener() {
            @SuppressLint({ "SdCardPath", "SdCardPath" })
            @Override
            public void onClick(DialogInterface arg0, int arg1) {
                if (Environment.getExternalStorageState().equals(
                        Environment.MEDIA_MOUNTED)) {
                    // File sdCardDir =
                    // Environment.getExternalStorageDirectory();//获取SDCard目录
                    // File saveFile = new File(sdCardDir, "MyBudget.db");
                    File director = new File("/sdcard/MrBill");// 创建目录
                    File file = new File("/sdcard/MrBill/MyBudget.db");// 创建文件
                    if (!director.exists()) {
                        director.mkdirs();
                    }
                    if (!file.exists()) {
                        try {
                            FileInputStream fis = new FileInputStream(
                                    "/data/data/com.coderui.studentbudget/databases/MyBudget.db");
                            FileOutputStream fos = new FileOutputStream(file);
                            byte[] buffer = new byte[1024];
                            int length = 0;
                            while ((length = fis.read(buffer)) > 0) {
                                fos.write(buffer, 0, length);
                            }
                            fos.flush();
                            fos.close();
                            fis.close();
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    } else {
                        file.delete();
                        try {
                            FileInputStream fis = new FileInputStream(
                                    "/data/data/com.coderui.studentbudget/databases/MyBudget.db");
                            FileOutputStream fos = new FileOutputStream(file);
                            byte[] buffer = new byte[1024];
                            int length = 0;
                            while ((length = fis.read(buffer)) > 0) {
                                fos.write(buffer, 0, length);
                            }
                            fos.flush();
                            fos.close();
                            fis.close();
                        } catch (Exception e) {
                            e.printStackTrace();
                        }
                    }
                }
                Toast.makeText(SettingActivity.this, "备份成功", Toast.LENGTH_SHORT)
                        .show();
            }
        });
        builder.setNegativeButton("恢复", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
            }
        });
        builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                // TODO Auto-generated method stub
            }
        });
        builder.create().show();