<!-- 在SDCard中创建与删除文件权限 -->

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

    <!-- 往SDCard写入数据权限 -->

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

package com.example.yanlei.wifi;

import android.app.AlertDialog;

import android.content.DialogInterface;

import android.os.Bundle;

import android.os.Environment;

import android.support.v7.app.AppCompatActivity;

import android.text.method.ScrollingMovementMethod;

import android.view.Menu;

import android.widget.TextView;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.InputStream;

import java.io.InputStreamReader;

import java.util.ArrayList;

import java.util.List;

import jxl.Cell;

import jxl.Sheet;

import jxl.Workbook;

public class MainActivity extends AppCompatActivity {

    TextView txt = null;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        txt = (TextView)findViewById(R.id.txt_show);

        txt.setMovementMethod(ScrollingMovementMethod.getInstance());

        ShowMessage("ok2");

        //readtxt();

        readExcel();

        ShowMessage("ok3");

    }

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.

        //getMenuInflater().inflate(R.menu.main, menu);

        return true;

    }

    /**

     * 获取内置SD卡路径

     *

     * @return

     */

    public String getInnerSDCardPath() {

        File sdDir = null;

        boolean sdCardExist = Environment.getExternalStorageState()

                .equals(android.os.Environment.MEDIA_MOUNTED);   //判断sd卡是否存在

        if (sdCardExist) {

            sdDir = Environment.getExternalStorageDirectory();//获取跟目录

        }

        String Path = sdDir.toString();

        return Path;

    }

    public String getSDPath() {

        List<String> lResult = new ArrayList<String>();

        try {

            Runtime rt = Runtime.getRuntime();

            Process proc = rt.exec("mount");

            InputStream is = proc.getInputStream();

            InputStreamReader isr = new InputStreamReader(is);

            BufferedReader br = new BufferedReader(isr);

            String line;

            while ((line = br.readLine()) != null) {

                if (line.contains("extSdCard")) {

                    String[] arr = line.split(" ");

                    String path = arr[1];

                    File file = new File(path);

                    if (file.isDirectory()) {

                        lResult.add(path);

                    }

                }

            }

            isr.close();

        } catch (Exception e) {

        }

        int num=lResult.size();

        //ShowMessage("外盘的个数："+num);

        if (num>0) {

            return lResult.get(0).toString();

        }

        else

        {

            return "";

        }

    }

    /* @param path 文件夹路径

       */

    public static boolean isExist(String path) {

        File file = new File(path);

        //判断文件夹是否存在,如果不存在则创建文件夹

        if (!file.exists()) {

            //file.mkdir();

            return false;

        }

        return true;

    }

    //判断文件是否存在

    public boolean fileIsExists(String strFile) {

        try {

            File f = new File(strFile);

            if (!f.exists()) {

                return false;

            }

        } catch (Exception e) {

            return false;

        }

        return true;

    }

    public void ShowMessage(String str) { //

        new AlertDialog.Builder(this)

                .setMessage(str)

                .setPositiveButton("确定",

                        new DialogInterface.OnClickListener() {

                            public void onClick(DialogInterface dialoginterface, int i) {

                                //按钮事件

                            }

                        })

                .show();

    }

    public String getFilePath() {

        String path = getSDPath();

        if (path!="") {

            if (isExist(path + "/qqq.txt")) {

                return path;

            }

        }

        path = getInnerSDCardPath();

        if (isExist(path + "/qqq.txt")) {

            return path;

        }

        return path;

    }

    public static String readFile(String filePathAndName) {

        String fileContent = "";

        try {

            File f = new File(filePathAndName);

            if(f.isFile()&&f.exists()){

                InputStreamReader read = new InputStreamReader(new FileInputStream(f),"gbk");

                BufferedReader reader=new BufferedReader(read);

                String line;

                while ((line = reader.readLine()) != null) {

                    fileContent += line;

                }

                read.close();

            }

        } catch (Exception e) {

            System.out.println("读取文件内容操作出错");

            e.printStackTrace();

        }

        return fileContent;

    }

    public void readtxt() {

        {

            String path=getFilePath();

            ShowMessage("路径:"+path);

            if (path=="")

            {

                ShowMessage("文件："+path+"/qqq.txt"+"不存在");

                return;

            }

            ShowMessage("11111111111111111111" );

            ShowMessage(readFile(path + "/qqq.txt"));

            ShowMessage("222222222" );

        }

    }

}