android存储方式之文件存储

xml存储：sharepreferences 存放在shared_prefs文件夹下

case R.id.button_write:
/**
                 * 以xml格式存储
                 */
SharedPreferences sharedPreferences = getSharedPreferences("myshare",MODE_PRIVATE);
//              SharedPreferences sharedPreferences = getPreferences(MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPreferences.edit();
                editor.putString("data",mEditText.getText().toString());
                editor.commit();
break;
case R.id.button_read:
                SharedPreferences preferences = getSharedPreferences("myshare",MODE_PRIVATE);
//              SharedPreferences preferences = getPreferences(MODE_PRIVATE);
String s = preferences.getString("data","默认值");
mTextView.setText(s);
break;

文件存储：缓存（内部），本地文件存储（外部）

缓存在cache下:

case R.id.button_writecache:

try {
            FileOutputStream outputStream = openFileOutput("hellocache.txt", MODE_PRIVATE);
            PrintWriter writer = new PrintWriter(new OutputStreamWriter(outputStream));
            writer.write(mEditText.getText().toString());
            writer.flush();
            writer.close();
            outputStream.close();
break;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
}

private void readcache() {
try {
        FileInputStream inputStream = openFileInput("hellocache.txt");
        BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
        String line = br.readLine();
mTextView.setText(line);
        br.close();
        inputStream.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void writeCacheDir() {
    File file = new File(getCacheDir(),"helloworld.txt");
if(!file.exists()){
try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
try {
        FileOutputStream outputStream = new FileOutputStream(file);
        PrintWriter writer = new PrintWriter(outputStream);
        writer.write(mEditText.getText().toString());
        writer.flush();
        writer.close();
        outputStream.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void readCacheDir() {
    File fileRead =new File(getCacheDir(),"helloworld");
if(!fileRead.exists()){
try {
            fileRead.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
try {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(fileRead)));
        String data = bufferedReader.readLine();
mTextView.setText(data);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}
外部存储在Sdcard下,需要添加权限：
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
private void readSDcard() {
    File file = new File(Environment.getExternalStorageDirectory(),"hellosdcard");
if(!file.exists()){
try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
try {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(file)));
        String data = bufferedReader.readLine();
mTextView.setText(data);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

private void writeSDcard() {
    File file = new File(Environment.getExternalStorageDirectory(),"hellosdcard.txt");
if(!file.exists()){
try {
            file.createNewFile();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
try {
        FileOutputStream outputStream = new FileOutputStream(file);
        PrintWriter writer = new PrintWriter(outputStream);
        writer.write(mEditText.getText().toString());
        writer.flush();
        writer.close();
        outputStream.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}