Android access to file permissions four modes introduction _android

Access permissions for Linux files

* In Android, each application is an independent user
* DRWXRWXRWX
* 1th: D means folder,-indicates file
* 第2-4位: rwx, representing the owner of this file (the application that created the file) the user's permissions to the file
* R: Read
* W: Write
* x: Execute

* 第5-7位: RWX, which represents the permissions of users in the same group as the file owner user to the file

* 第8-10位: rwx, which means that users of other user groups have permissions to the file

Four modes of Openfileoutput

* MODE_PRIVATE:-RW-RW----

* MODE_APPEND:-RW-RW----

* mode_world_writeable:-rw-rw--w-

* mode_world_readable:-rw-rw-r--

The following combat:

Finish the layout first

<linearlayout xmlns:android= "http://schemas.android.com/apk/res/android"


xmlns:tools= "http:// Schemas.android.com/tools "
android:layout_width=" match_parent "
android:layout_height=" Match_parent "
android:orientation= "vertical"
android:paddingbottom= "@dimen/activity_vertical_margin"
android: paddingleft= "@dimen/activity_horizontal_margin"
android:paddingright= "@dimen/activity_horizontal_margin"
android:paddingtop= "@dimen/activity_vertical_margin"
tools:context= ". Mainactivity ">
<button
android:layout_width=" wrap_content "
android:layout_height=" Wrap_ Content "
android:text=" button 1 "
android:onclick=" click1/>
</LinearLayout>

Add button Event

public void Click1 (View v) {
//data/data/com.wuyudong.permission.files
try {
FileOutputStream fos = Openfileoutput ("Info1.txt", mode_private);
Fos.write ("Private Mode". GetBytes ());
Fos.close ();
} catch (Exception e) {
//TODO auto-generated catch block
e.printstacktrace ();
}
}

Click on the button to form the corresponding file Info1.txt, as shown

And then generate the other button layouts:

The corresponding code is as follows:

Package com.wuyudong.permission;
Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import Android.os.Bundle;
Import android.app.Activity;
Import Android.view.View; public class Mainactivity extends activity {@Override protected void onCreate (Bundle savedinstancestate) {super.oncreate
(savedinstancestate);
Setcontentview (R.layout.activity_main); } public void Click1 (View v) {//Data/data/com.wuyudong.permission.files try {fileoutputstream fos = openfileoutput ("inf
O1.txt ", mode_private);
Fos.write ("Private Mode". GetBytes ());
Fos.close ();
catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();}} public void Click2 (View v) {//Data/data/com.wuyudong.permission.files try {fileoutputstream fos = openfileoutput ("Info2
. txt ", mode_append);
Fos.write ("Append mode". GetBytes ());
Fos.close ();
catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();}} public void Click3 (View v) {//Data/data/com.wuyudong.permission.files try {FILEOUTPUTstream fos = openfileoutput ("Info3.txt", mode_world_readable);
Fos.write ("Global readable Mode". GetBytes ());
Fos.close ();
catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();}} public void Click4 (View v) {//Data/data/com.wuyudong.permission.files try {fileoutputstream fos = openfileoutput ("Info4
. txt ", mode_world_writeable);
Fos.write ("Private Mode". GetBytes ());
Fos.close ();
catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();}} }

Click the button in turn to generate the appropriate permissions file:

Create an application to read the previously generated info3.txt file

 package com.wuyudong.other; import java.io.BufferedReader; import java.io.File; import
Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import Java.io.InputStreamReader;
Import Android.os.Bundle;
Import android.app.Activity;
Import Android.view.Menu;
Import Android.view.View;
Import Android.widget.Toast; public class Mainactivity extends activity {@Override protected void onCreate (Bundle savedinstancestate) {super.oncreate
(savedinstancestate);
Setcontentview (R.layout.activity_main); public void Click (View v) {File File = new file ("Data/data/com.wuyudong.permission/files/info3.txt"); try {fileinputst
Ream FIS = new FileInputStream (file);
Convert byte flows to character streams bufferedreader br = new BufferedReader (new InputStreamReader (FIS));
String text = Br.readline ();
Toast.maketext (this, text, 0). Show ();
catch (Exception e) {//TODO auto-generated catch block E.printstacktrace ();}} }

The above is a small set to introduce the Android access to file permissions of four of the relevant content, I hope to help you, if you want to learn more content please pay attention to cloud Habitat community website!