In java, after getting root permissions, how can I open files with it? Can I open them with File class or do I have to use a command?
You will have to use the su command.
I suggest you have a look at how to use su
Sample code to read a file ( I haven't tested it but it should give you an idea ):
public static void runAsRoot(String[] cmds){
try {
Process p = Runtime.getRuntime().exec("su");
BufferedReader reader = new BufferedReader(p.getInputStream());
StringBuilder out = new StringBuilder();
String line;
while ((line = reader.readLine()) != null) {
out.append(line); // add everything to StringBuilder
// here you can have your logic of comparison.
if(line.toString().equals(".")) {
// do something
}
}
} catch(IOException e) {
e.printStackTrace();
} catch(InterruptedException e) {
e.printStackTrace();
}
Related
I need to create a folder on my remote machine. For testing purpose, I am trying to create folder on my own machine using my machine IP address. My Ubuntu machine IP address is XX.X.X.XX. I want to create a folder called E book on my home directory using the following java code snippet. But the following doesn't create a folder. Please help.
boolean folder = new java.io.File("//XX.X.X.XX/home/EBook").mkdirs();
System.out.println(folder);
You can accomplish this by executing a process in java:
BufferedReader stdError = null;
try
{
// change the you and server accordingly
String command = "ssh you#server \"mkdir /home/name/EBook\"";
Process p = Runtime.getRuntime().exec(command);
stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
// read any errors from the attempted command
System.out.println("Here is the standard error of the command (if any):\n");
String s = null;
while ((s = stdError.readLine()) != null)
{
System.out.println(s);
}
}
catch (IOException e)
{
e.printStackTrace();
}
finally
{
if (stdError != null)
{
try
{
stdError.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
}
I am new to Android development, and I try to access to the internal terminal (/bin/bash, ...) of Android phone using a java method.
Do you know if such java method exist?
Thanks
You can use Runtime and Process to achieve your task.
private static String executeCommand(String command) {
Process process = null;
BufferedReader reader = null;
String result = "";
try {
String line;
process = Runtime.getRuntime().exec(command);
reader = new BufferedReader(new InputStreamReader(process.getInputStream()));
while ((line = reader.readLine()) != null)
result += line + "\n";
} catch (final Exception e) {
e.printStackTrace();
} finally {
try {
if (reader != null)
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
if (process != null)
process.destroy();
} catch (Exception e) {
e.printStackTrace();
}
}
return result;
}
Where command is any available terminal commands like PING 8.8.8.8
I'm not entirely sure as to what you mean by "accessing the internal terminal". But if you would like to execute commands take a look at the documentation of the Runtime class.
Here's an example on how to use it.
I have put a file "template.html" inside RAW folder and I want to read it into a InputStream. But it is returning me null. Can't understand what is wrong in the below code
e.g. fileName passed as parameter is "res/raw/testtemplate.html"
public String getFile(String fileName) {
InputStream input = this.getClass().getClassLoader().getResourceAsStream(fileName);
return getStringFromInputStream(input);
}
Also, there might be a better solution by putting these files in a particular subfolder and putting it inside Asset folder but then I believe I would need to pass context in AssetManager. I don't understand that solution, sorry I am new to android development. Can someone shed some light regarding how this approach can be achieved.
EDIT
I have started implementing this solution with Assets. Below method is supposed to return a string containing the entire text of the file stored as template.html.
getFile("template.html") // I am sending extension this time
Problem getting error getAssets() is undefined.
public String getFile(String fileName) {
BufferedReader reader = null;
StringBuilder sb = new StringBuilder();
String line;
try {
reader = new BufferedReader(new InputStreamReader(getAssets().open(fileName)));
while ((line = reader.readLine()) != null) {
sb.append(line);
}
}
catch (IOException e) {
e.printStackTrace();
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return sb.toString();
}
use this
new BufferedInputStream(getResources().openRawResource(filepath));
this will return a buffered input stream
The file name should be without extension :
InputStream ins = getResources().openRawResource(
getResources().getIdentifier("raw/FILENAME_WITHOUT_EXTENSION",
"raw", getPackageName()));
For this purposes uses assets folder:
assets/
This is empty. You can use it to store raw asset files. Files that you save here are compiled into an .apk file as-is, and the original filename is preserved. You can navigate this directory in the same way as a typical file system using URIs and read files as a stream of bytes using the AssetManager. For example, this is a good location for textures and game data.
So, you could easy get access at assets with context: context.getAssets()
BufferedReader reader = null;
try {
reader = new BufferedReader(
new InputStreamReader(context.getAssets().open("filename.txt")));
}
} catch (IOException e) {
//log the exception
} finally {
if (reader != null) {
try {
reader.close();
} catch (IOException e) {
//log the exception
}
}
}
I have a file with some non-ASCII character like
set myval;[2K[DESC[DESC[D
and I have a Java code to read the file
public static void main(String[] args) {
BufferedReader br = null;
try {
String sCurrentLine;
br = new BufferedReader(new FileReader("output.txt"));
while ((sCurrentLine = br.readLine()) != null) {
System.out.println(sCurrentLine);
}
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (br != null) {
br.close();
}
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
In Netbeans those non ASCII are not shown but in Eclipse console those character are displayed as it is.
I want to know how Netbeans were able to remove those character as i need to clean up my files for those non ASCII characters.
Thanks
The best way to do this is to read the file as bytes, and then configure a specific CharsetDecoder to remove the bytes you do not want to capture.
Goal: Print the data from a .dat file to the console using Eclipse.
(Long-Term Goal): Executable that I can pass a .dat file to and it creates a new txt file with the data formatted.
The .dat: I know the .dat file contains control points that I will need to create a graph with using ECMAScript.
Eclipse Setup:
Created Java Project
New > Class .. called the Class FileRead
Now I have FileRead.java which is:
1/ package frp;
2/
3/ import java.io.BufferedReader;
4/ import java.io.File;
5/ import java.io.FileReader;
6/
7/ public class FileRead {
8/
9/ public static void main(String[] args) {
10/ FileReader file = new FileReader(new File("dichromatic.dat"));
11/ BufferedReader br = new BufferedReader(file);
12/ String temp = br.readLine();
13/ while (temp != null) {
14/ temp = br.readLine();
15/ System.out.println(temp);
16/ }
17/ file.close();
18/ }
19/
20/ }
Please note this approach was borrowed from here: https://stackoverflow.com/a/18979213/3306651
1st Challenge: FileNotFoundException on LINE 10
Screenshot of Project Explorer:
QUESTION: How to correctly reference the .dat file?
2nd Challenge: Unhandled exception type IOException LINES 12, 14, 17
QUESTION: How to prevent these exceptions?
Thank you for your time and effort to help me, I am recreating Java applets using only JavaScript. So, I'm looking to create java tools that extract data I need to increase productivity. If you are interested in phone/web app projects involving JavaScript, feel free to contact me 8503962891
1. Without changing your code, you must place the file in the project's root folder.
Otherwise, reference it as src/frp/dichromatic.dat
2. Doing something like this:
public static void main(String[] args) {
FileReader file = null;
try {
file = new FileReader(new File("dichromatic.dat"));
} catch (FileNotFoundException e1) {
System.err.println("File dichromatic.dat not found!");
e1.printStackTrace();
}
BufferedReader br = new BufferedReader(file);
String line;
try {
while ((line = br.readLine()) != null) {
System.out.println(line);
}
} catch (IOException e) {
System.err.println("Error when reading");
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
System.err.println("Unexpected error");
e.printStackTrace();
}
}
}
}
3. Creation of a new txt file "formatted". In this example, the formatting will be settings the characters to uppercase.
public static void main(String[] args) {
FileReader file = null;
BufferedWriter bw = null;
File outputFile = new File("output.formatted");
try {
file = new FileReader(new File("dichromatic.dat"));
} catch (FileNotFoundException e1) {
System.err.println("File dichromatic.dat not found!");
e1.printStackTrace();
}
try {
bw = new BufferedWriter(new FileWriter(outputFile));
} catch (IOException e1) {
System.err.println("File is not writtable or is not a file");
e1.printStackTrace();
}
BufferedReader br = new BufferedReader(file);
String line;
String lineformatted;
try {
while ((line = br.readLine()) != null) {
lineformatted = format(line);
bw.write(lineformatted);
// if you need it
bw.newLine();
}
} catch (IOException e) {
System.err.println("Error when processing the file!");
e.printStackTrace();
} finally {
if (br != null) {
try {
br.close();
} catch (IOException e) {
System.err.println("Unexpected error");
e.printStackTrace();
}
}
if (bw != null) {
try {
bw.close();
} catch (IOException e) {
System.err.println("Unexpected error");
e.printStackTrace();
}
}
}
}
public static String format(String line) {
// replace this with your needs
return line.toUpperCase();
}
I would strongly recommend spending some time reading through the Java Trails Tutorials. To answer your specific question, look at Lesson: Exceptions.
To oversimplify, just wrap the file-handling code in a try...catch block. By example:
package frp;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
public class FileRead {
public static void main(String[] args) {
try {
FileReader file = new FileReader(new File("dichromatic.dat"));
BufferedReader br = new BufferedReader(file);
String temp = br.readLine();
while (temp != null) {
temp = br.readLine();
System.out.println(temp);
}
file.close();
} catch (FileNotFoundException fnfe) {
System.err.println("File not found: " + fnfe.getMessage() );
} catch (IOException ioe) {
System.err.println("General IO Error encountered while processing file: " + ioe.getMessage() );
}
}
}
Note that ideally, your try...catch should wrap the smallest possible unit of code. So, wrap the FileReader separately, and "fail-fast" if the file isn't found, and wrap the readLine loop in its own try...catch. For more examples and a better explanation of how to deal with exceptions, please reference the link I provided at the top of this answer.
Edit: issue of file path
Not finding the file has to do with the location of the file relative to the root of the project. In your original post, you reference the file as "dichromatic.dat" but relative to the project root, it is in "src/frp/dichromatic.dat". As rpax recommends, either change the string that points to the file to properly reference the location of the file relative to the project root, or move the file to project root and leave the string as-is.