安卓如何将TXT文件写到特定路径

其实就一个方法，就不贴所有代码了。

    /**
     * 写入文件方法
     * @param content
     */
    public static void write(String content) {
        try {
            //判断实际是否有SD卡，且应用程序是否有读写SD卡的能力，有则返回true
            if (Environment.getExternalStorageState().equals(
                    Environment.MEDIA_MOUNTED)) {
                // 获取SD卡的目录
                File sdCardDir = Environment.getExternalStorageDirectory();
                String path = "/APP/";
                File dir = new File(sdCardDir+path);
                if (!dir.exists()) {
                    dir.mkdirs();
                }
                File targetFile = new File(sdCardDir.getCanonicalPath() + path+"aaa.txt");
                //使用RandomAccessFile是在原有的文件基础之上追加内容，
                //而使用outputstream则是要先清空内容再写入
                RandomAccessFile raf = new RandomAccessFile(targetFile, "rw");
                //光标移到原始文件最后，再执行写入
                raf.seek(targetFile.length());
                raf.write(content.getBytes());
                raf.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

package com.example.linfeng.myapplication;

import android.os.Environment;

import java.io.File;
import java.io.RandomAccessFile;
import java.text.SimpleDateFormat;
import java.util.Date;

/**
 * Created by LinFeng on 2017/11/13.
 */

public class TextHelper {

    public static void write(String content, String PathName, String FileName) {
        try {
            //判断实际是否有SD卡，且应用程序是否有读写SD卡的能力，有则返回true

            if (Environment.getExternalStorageState().equals(
                    Environment.MEDIA_MOUNTED)) {
                // 获取SD卡的目录
                File sdCardDir = Environment.getExternalStorageDirectory();
                //Log.i("paht",sdCardDir.toString());
                String path = "/" + PathName + "/";
                //如果不存在，就创建目录
                File dir = new File(sdCardDir + path);
                if (!dir.exists()) {
                    dir.mkdirs();
                }
                File targetFile = new File(sdCardDir.getCanonicalPath() + path + FileName + ".dat");
                //使用RandomAccessFile是在原有的文件基础之上追加内容，
                //而使用outputstream则是要先清空内容再写入
                RandomAccessFile raf = new RandomAccessFile(targetFile, "rw");
                //光标移到原始文件最后，再执行写入
                raf.seek(targetFile.length());
                raf.write(content.getBytes());
                raf.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //写头文件，如果不存在写，存在就不写
    public  static  void writeHead(String path,String fileName,char type){

        String string=Environment.getExternalStorageDirectory()+"/" + path + "/"+fileName+".dat";
        if (!fileIsExists(string)){
           switch (type){
               case 'I':
                   String content = "Type=Inventory"+"\r\n"+"Date="+getStringDate()+"\r\n"+"ScannerNo=01";
                   write(content,path,fileName);
                   break;
               case 'M':
                   write("Type=Market"+"\r\n",path,fileName);
                   break;
               case 'R':
                   write("Type=Return"+"\r\n",path,fileName);
                   break;
           }
        }else{

        }
    }

    //判断文件是否存在
    public static boolean fileIsExists(String strFile) {
        try {
            File f = new File(strFile);
            if (!f.exists()) {
                return false;
            }
        } catch (Exception e) {
            return false;
        }
        return true;
    }

    //获取当前时间，格式为：yyyyMMdd HH:mm:ss
    public static String getStringDate() {
        Date currentTime = new Date();
        SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd HH:mm:ss");
        String dateString = formatter.format(currentTime);
        return dateString;
    }
}