package com.xxx.util; import android.os.Environment;import android.util.Log; import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.InputStreamReader;import java.io.RandomAccessFile; /** * 文件工具類 * Created by zst on 2018/2/1. */public class FileUtils {     // 將字符串寫入到文本文件中  public static void writeTxtToFile(String strcontent, String filePath, String fileName) {    //生成文件夾之后，再生成文件，不然會出錯    makeFilePath(filePath, fileName);     String strFilePath = filePath + fileName;    // 每次寫入時，都換行寫    String strContent = strcontent + "/r/n";    try {      File file = new File(strFilePath);      if (!file.exists()) {        Log.d("TestFile", "Create the file:" + strFilePath);        file.getParentFile().mkdirs();        file.createNewFile();      }      RandomAccessFile raf = new RandomAccessFile(file, "rwd");      raf.seek(file.length());      raf.write(strContent.getBytes());      raf.close();    } catch (Exception e) {      Log.e("TestFile", "Error on write File:" + e);    }  }   //生成文件  public static File makeFilePath(String filePath, String fileName) {    File file = null;    makeRootDirectory(filePath);    try {      file = new File(filePath + fileName);      if (!file.exists()) {        file.createNewFile();      }    } catch (Exception e) {      e.printStackTrace();    }    return file;  }   //生成文件夾  public static void makeRootDirectory(String filePath) {    File file = null;    try {      file = new File(filePath);      if (!file.exists()) {        file.mkdir();      }    } catch (Exception e) {      Log.i("error:", e + "");    }  }   //讀取指定目錄下的所有TXT文件的文件內容  public static String getFileContent(File file) {    String content = "";    if (!file.isDirectory()) { //檢查此路徑名的文件是否是一個目錄(文件夾)      if (file.getName().endsWith("txt")) {//文件格式為""文件        try {          InputStream instream = new FileInputStream(file);          if (instream != null) {            InputStreamReader inputreader                = new InputStreamReader(instream, "UTF-8");            BufferedReader buffreader = new BufferedReader(inputreader);            String line = "";            //分行讀取            while ((line = buffreader.readLine()) != null) {              content += line + "/n";            }            instream.close();//關閉輸入流          }        } catch (java.io.FileNotFoundException e) {          Log.d("TestFile", "The File doesn't not exist.");        } catch (IOException e) {          Log.d("TestFile", e.getMessage());        }      }    }    return content;  } }

FileUtils.writeTxtToFile(idPASideBase64, "/sdcard/Gyt/", "idPASide.txt");

String idPASideBase64 = FileUtils.getFileContent(new File("/sdcard/Gyt/idPASide.txt"));