公司响应式网站建设平台,哪里可以做网站优化,牛博网站建设,wordpress 登录页美化外部存储#xff0c;个人理解是在app作用域之外存储#xff0c;就是数据没有和app做关联#xff0c;app卸载后#xff0c;它依旧存在而不再是之前手机本身存储空间和sd卡的区别#xff0c;现在安卓手机已经不携带可拆卸的SD卡androidManifest.xml 需要写入读写权限简单布局…外部存储个人理解是在app作用域之外存储就是数据没有和app做关联app卸载后它依旧存在而不再是之前手机本身存储空间和sd卡的区别现在安卓手机已经不携带可拆卸的SD卡androidManifest.xml 需要写入读写权限简单布局:java代码: 需要动态权限android8以后真机都需要模拟器可能不需要package com.example.handleproject;import androidx.annotation.NonNull;import androidx.appcompat.app.AppCompatActivity;import androidx.core.app.ActivityCompat;import androidx.core.content.ContextCompat;import android.Manifest;import android.content.pm.PackageManager;import android.os.Bundle;import android.os.Environment;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.TextView;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;public class externalActivity extends AppCompatActivity {private TextView mTextView;private Button save;private Button read;private TextView showText;Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_external);mTextViewfindViewById(R.id.text);savefindViewById(R.id.save);readfindViewById(R.id.read);showTextfindViewById(R.id.showTxt);int permisson ContextCompat.checkSelfPermission(this, Manifest.permission.WRITE_EXTERNAL_STORAGE);if(permisson! PackageManager.PERMISSION_GRANTED){// TODO: 2020-08-14 动态申请权限ActivityCompat.requestPermissions(this,new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE},1);}}public void oprerate(View v){String path Environment.getExternalStorageDirectory().getAbsolutePath()/imooc.txt;Log.d(External, path);switch (v.getId()){case R.id.save:File fnew File(path);try{if(!f.exists()){f.createNewFile();}//用追加的模式写入FileOutputStream fosnew FileOutputStream(path,true);String strmTextView.getText().toString();fos.write(str.getBytes());}catch (IOException E){Log.d(External err, E.getMessage());}break;case R.id.read:try{FileInputStream fisnew FileInputStream(path);byte[] bnew byte[1024];int lenfis.read(b);String str2new String(b,0,len);showText.setText(str2);fos.close();//不要忘记关闭写入}catch (IOException E){E.printStackTrace();}break;}}Overridepublic void onRequestPermissionsResult(int requestCode, NonNull String[] permissions, NonNull int[] grantResults) {super.onRequestPermissionsResult(requestCode, permissions, grantResults);}}存储地址在mnt/sdcard(androidStudio上面查看) 的更目录下面在手机上看时候其实是在根目录下(手机文件管理器显示是内部存储,也可能是其他的)更详细的说明
