How to access an Android database file to a memory card _android

Nonsense not much said, directly to everyone to paste the code, the specific code as follows

<?xml version= "1.0" encoding= "Utf-8"?> <linearlayout xmlns:android= "http://schemas.android.com/apk/res/" Android "Android:layout_width=" Match_parent "android:layout_height=" match_parent "android:orientation=" vertical "
> <button android:id= "@+id/save" android:layout_width= "wrap_content" android:layout_height= "Wrap_content" android:text= "Save data (File)"/> <button android:id= "@+id/read" android:layout_width= "Wrap_content" Android:
layout_height= "Wrap_content" android:text= "read data (File)"/> </LinearLayout> package Com.example.yanlei.wifi;
Import Android.os.Bundle;
Import android.os.Environment;
Import android.support.v7.app.AppCompatActivity;
Import Android.view.View;
Import Android.view.View.OnClickListener;
Import Android.widget.Button;
Import Android.widget.Toast;
Import Java.io.File;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import Java.io.PrintStream;
Import Java.util.Scanner; public class MainactiviTy extends appcompatactivity {private button btnsave=null; private button btnread=null; private File file=null; private s
Tatic final String filename= "Data.txt"; @Override protected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate); Setcontentview (
R.layout.activity_main);
Btnsave= (Button) Super.findviewbyid (R.id.save);

Btnread= (Button) Super.findviewbyid (R.id.read);

Btnsave.setonclicklistener (New Onclicklistener () {public void OnClick (View v) {PrintStream ps=null; Determine if the external storage card exists if (! Environment.getexternalstoragestate (). Equals (environment.media_mounted)) {Toast.maketext Getapplicationcontext ( ), "Read failed, SD memory card does not exist!"
", Toast.length_long). Show ();
Return ///Initialize File String path=environment.getexternalstoragedirectory (). toString () +file.separator + "Genwoxue" +
File.separator +filename;

File=new File (path);
If the parent folder for the current file does not exist, create the Genwoxue folder if (!file.getparentfile (). exists ()) File.getparentfile (). Mkdirs (); Write file try {PS = new PrintStream (new FileOutputStream (file)); Ps.println ("Follow me to learn Web site: www.genwoxue.com");
Ps.println ("");
Ps.println ("e-mail: hello@genwoxue.com"); catch (FileNotFoundException e) {e.printstacktrace ();}
finally{ps.close ();} Toast.maketext (Getapplicationcontext (), "Save success!"
", Toast.length_long). Show ();});

Btnread.setonclicklistener (New Onclicklistener () {public void OnClick (View v) {stringbuffer info=new stringbuffer (); Determine if the external storage card exists if (! Environment.getexternalstoragestate (). Equals (environment.media_mounted)) {Toast.maketext Getapplicationcontext ( ), "Read failed, SD memory card does not exist!"
", Toast.length_long). Show ();
Return ///Initialize File String path=environment.getexternalstoragedirectory (). toString () +file.separator + "Genwoxue" +
File.separator +filename;

File=new File (path); if (!file.exists ()) {Toast.maketext (Getapplicationcontext ()), "file does not exist!"
", Toast.length_long). Show ();
Return
//Read the contents of the file Scanner scan=null;
try {scan=new Scanner (new FileInputStream (file)) while (Scan.hasnext ()) {Info.append (Scan.next ()). Append ("☆☆☆\n"); Toast.maketext (Getapplicationcontext(), info.tostring (), Toast.length_long). Show (); catch (FileNotFoundException e) {e.printstacktrace ();}
finally{scan.close ();}
}); }
}

Permissions

<?xml version= "1.0" encoding= "Utf-8"?> <manifest xmlns:android= "http://schemas.android.com/apk/res/" Android "package=" Com.example.yanlei.wifi > <!--Create and delete file permissions in SDcard--> <uses-permission android:name= " Android.permission.MOUNT_UNMOUNT_FILESYSTEMS "/> <!--Write data permissions to SDcard--> <uses-permission android:name=" Android.permission.READ_EXTERNAL_STORAGE "/> <uses-permission android:name=" android.permission.WRITE_ External_storage "/> <application android:allowbackup=" true "android:icon=" @mipmap/ic_launcher "Android:label = "@string/app_name" android:theme= @style/apptheme "> <activity android:name=". Mainactivity "android:label=" @string/app_name "> <intent-filter> <action android:name=" Android.intent.action.MAIN "/> <category android:name=" Android.intent.category.LAUNCHER "/> </ intent-filter> </activity> </application> </manifest> <uses-permission android:name= " Android.permission.READ_EXTERNAL_STORAGE "/> <uses-permission android:name= "Android.permission.WRITE_EXTERNAL_STORAGE"/> 

The above is a small part of the introduction of the Android database file access to the storage card method, I hope to help you, this article is not good to write please heroes forgive me!