Android在外部存储器中读取数据

package com.itheima.rwinrom;

import java.io.BufferedReader;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;

import java.io.InputStreamReader;

import org.apache.http.entity.InputStreamEntity;

import com.itheima.rwinsd.R;

import android.os.Bundle;

import android.os.Environment;

import android.annotation.SuppressLint;

import android.app.Activity;

import android.view.Menu;

import android.view.View;

import android.widget.CheckBox;

import android.widget.EditText;

import android.widget.Toast;

public class MainActivity extends Activity {

private EditText et_name;

private EditText et_pass;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

et_name = (EditText) findViewById(R.id.et_name);

et_pass = (EditText) findViewById(R.id.et_pass);

readAccount();

}

public void readAccount(){

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){

File file = new File("sdcard/info.txt");

if(file.exists()){

try {

FileInputStream fis = new FileInputStream(file);

//把字节流转换成字符流

BufferedReader br = new BufferedReader(new InputStreamReader(fis));

//读取txt文件里的用户名和密码

String text = br.readLine();

String[] s = text.split("##");

et_name.setText(s[0]);

et_pass.setText(s[1]);

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

}

}

public void login(View v){

String name = et_name.getText().toString();

String pass = et_pass.getText().toString();

CheckBox cb = (CheckBox) findViewById(R.id.cb);

//判断选框是否被勾选

if(cb.isChecked()){

//MEDIA_UNKNOWN:不能识别sd卡

//MEDIA_REMOVED:没有sd卡

//MEDIA_UNMOUNTED:sd卡存在但是没有挂载

//MEDIA_CHECKING:sd卡正在准备

//MEDIA_MOUNTED：sd卡已经挂载，可用

if(Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)){

//返回一个File对象，其路径是sd卡的真实路径

File file = new File(Environment.getExternalStorageDirectory(), "info.txt");

// File file = new File("sdcard/info.txt");

FileOutputStream fos;

try {

fos = new FileOutputStream(file);

fos.write((name + "##" + pass).getBytes());

fos.close();

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

else{

Toast.makeText(this, "sd卡不可用哟亲么么哒", 0).show();

}

}

//创建并显示吐司对话框

Toast.makeText(this, "登录成功", 0).show();

}

}