Android數據存儲方案 -- 文件存儲

Android中，文件存儲方案也比較簡單，一般使用 FileOutputStream/BufferedWriter寫入文件，使用FileInputStream/BufferedReader讀出文件內容。不過，文件是存放在/data/data/com.xxx.test/files/文件夾下面。

下面，我們看看示例代碼，

                // Write contents to the file
                String data = "Hello World!";
                FileOutputStream out = null;
                BufferedWriter writer = null;
                try {
                    out = openFileOutput("testFile.txt", Context.MODE_PRIVATE);
                    writer = new BufferedWriter(new OutputStreamWriter(out));
                    writer.write(data);
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    try {
                        if (writer != null) {
                            writer.close();
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }

                // Read the contents from the file
                FileInputStream in = null;
                BufferedReader reader = null;
                StringBuilder content = new StringBuilder();
                try {
                    in = openFileInput("testFile.txt");
                    reader = new BufferedReader(new InputStreamReader(in));
                    String line = "";
                    while ((line = reader.readLine()) != null) {
                        content.append(line);
                    }
                }catch (IOException e) {
                    e.printStackTrace();
                } finally {
                    if (reader != null) {
                        try {
                            reader.close();
                        } catch(IOException e) {
                            e.printStackTrace();
                        }
                    }

                }
                Toast.makeText(this, content.toString(), Toast.LENGTH_SHORT).show();

上述方式的文件，只可以供自身程序使用，如果其他程序想訪問，則沒有權限。下面，我們介紹一種可以讓多個程序一起訪問文件的方式，

Log.e(TAG, copyContent.toString());
 
try {
    File fs = new File(Environment.getExternalStorageDirectory()+"/msc/" + fileName);
    FileOutputStream outputStream =new FileOutputStream(fs);
    outputStream.write(copyContent.getBytes());
    outputStream.flush();
    outputStream.close();
    Toast.makeText(getBaseContext(), "File created successfully", Toast.LENGTH_LONG).show();
    Log.e(TAG, "Successful");
} catch (FileNotFoundException e) {
    e.printStackTrace();
} catch (IOException e) {
    e.printStackTrace();
}

下面是讀外部文件的代碼範例，

mConfigPath = getExternalFilesDirs("test")[0].getAbsolutePath() + File.separator + "config.txt";    

public Map<String, String> getSingleParameters(String mConfigPath) {
        Map<String, String> mParametersList = new LinkedHashMap();
        String mKey = "";
        String mValue = "";

        try {
            FileReader mFileReader = new FileReader(mConfigPath);
            BufferedReader mReader = new BufferedReader(mFileReader);

            String mReadLine;
            while((mReadLine = mReader.readLine()) != null) {
                if (!mReadLine.startsWith("#") && mReadLine.trim().length() > 0) {
                    String[] mKeyValuePair = mReadLine.split("=");
                    mKey = mKeyValuePair[0].trim();
                    mValue = mKeyValuePair[1].trim();
                    mParametersList.put(mKey, mValue);
                }
            }

            mReader.close();
            mFileReader.close();
        } catch (FileNotFoundException var9) {
            var9.printStackTrace();
        } catch (IOException var10) {
            var10.printStackTrace();
        }

        return mParametersList;
    }