Android Read and Write File Tool Class Detailed Explanation

This article example for everyone to share Android read and write file tool class specific code, for your reference, the specific content is as follows

public class Utils {
  private static String path1 = Environment.getExternalStorageDirectory().getAbsolutePath();
  private static String path2 = Environment.getDownloadCacheDirectory().getAbsolutePath();
  private static String pathExt = "/111/222/333/444/555/";
  private static String fileName = "6.txt";
 
  public static void write(String str) {
    String filePath = null;
    boolean hasSDCard =Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
    if (hasSDCard) {
      filePath = path1 + pathExt + fileName;
    } else {
      filePath = path2 + pathExt + fileName;
    }
    try {
      File file = new File(filePath);
      if (!file.exists()) {
        //mkdirs() Method to generate multi-layer folders 
        //mkdir() Method generation 1 Layer-by-layer folder 
//        File dir = new File(file.getParent());
//        dir.mkdirs();
        file.getParentFile().mkdirs();// Generate folders on the outer layer of files 
        file.createNewFile();// Generate file 
      }
      FileOutputStream os = new FileOutputStream(file);
      os.write(str.getBytes());
      os.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
 
  public static String read() {
    String content = "";
    String filePath;
 
    boolean sdcard = Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED);
    if (sdcard) {
      filePath = path1 + pathExt + fileName;
    } else {
      filePath = path2 + pathExt + fileName;
    }
    try {
      File file = new File(filePath);
      if (file.exists()) {
        FileInputStream is = new FileInputStream(file);
        InputStreamReader inputReader = new InputStreamReader(is);// Set the stream read mode 
        BufferedReader buffReader = new BufferedReader(inputReader);
        String line;
        try {
          while (null != (line = buffReader.readLine())) {
            content += line + "\n";// File capacity read 
          }
          is.close();// Close the input stream 
        } catch (IOException e) {
          e.printStackTrace();
        } finally {
          try {
            if (null != is) {
              is.close();
            }
          } catch (IOException e) {
            e.printStackTrace();
          }
        }
      }
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    }
    return content;
  }
}

1. Add read and write permissions to the manifest file

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

2. Android 6.0 and above should dynamically apply for read and write permissions

ArrayList<String> permissionList = new ArrayList<>();
private String[] permissions = {
 "android.permission.READ_EXTERNAL_STORAGE",
 "android.permission.WRITE_EXTERNAL_STORAGE" };
// Check whether you have write permission 
// Judge the mobile phone version , If it is lower than 6.0  You do not need to apply for permission , Direct photograph 
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
 if (checkSelfPermission(permissions[0]) != PackageManager.PERMISSION_GRANTED) {
 permissionList.add(permissions[0]);
 }
 if (checkSelfPermission(permissions[1]) != PackageManager.PERMISSION_GRANTED) {
 permissionList.add(permissions[1]);
 }
 
 if (!permissionList.isEmpty()) {
 String[] permissions1 = permissionList.toArray(new String[permissionList.size()]);
 requestPermissions(permissions1, 1);
 } else {
 Utils.write("balabala");
 Utils.read();
 }
} else {
 Utils.write("balabala");
 Utils.read();
}
 
 
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
 switch (requestCode){
 case 1:
  if (PackageManager.PERMISSION_GRANTED == grantResults[0]){
  Utils.write("balabala");
  Utils.read();
  } else {
  Log.d(TAG, "fail: ");
  }
  break;
 }
}