PrintServiceLookup.lookupDefaultPrintService() returns NULL as I have a printer installed and set to default printer.
If I am using this in a simple program it works fine, but when I try to use it in my applet-based program it returns NULL.
Please send me some good solution for this problem.
In order to access the printer (or any resource on the host computer for that matter) the jar file in which the applet code resides has to be signed, and the user must accept the signer as a trusted party.
To sign the jar file, use the jarsigner program, which is part of he JDK. Jarsigner uses its own keystore, so if you have your own certificate, you must import the certificate to a keystore first. It can generate certificates as well, in the case you don't have any other certificate to sign the jar file with.
Documentation of the jarsigner tool can be found here.
Note that newer Java runtimes do ask the user if (s)he allows the code to access the printer, but I found that regardless of the answer, code in an unsigned jar file is prevented from accessing resources.
This code is working in an signed applet in windows with 1.7.0_55:
import javax.print.Doc;
import javax.print.DocFlavor;
import javax.print.DocPrintJob;
import javax.print.PrintService;
import javax.print.PrintServiceLookup;
import javax.print.SimpleDoc;
import javax.print.attribute.HashDocAttributeSet;
import javax.print.attribute.HashPrintRequestAttributeSet;
...
HashDocAttributeSet docAttr=new HashDocAttributeSet();
HashPrintRequestAttributeSet reqAttr=new HashPrintRequestAttributeSet();
try {
PrintService pserv = PrintServiceLookup.lookupDefaultPrintService();
if (pserv == null) {
System.out.println("ERROR-01: no default print service");
}
System.out.println("Printer: " + pserv.getName());
DocPrintJob job = pserv.createPrintJob();
DocFlavor flavor = DocFlavor.BYTE_ARRAY.AUTOSENSE;
String content = makeZplLabel();
Doc doc = new SimpleDoc(content.getBytes(), flavor, docAttr);
job.print(doc, reqAttr);
} catch (Exception e) {
System.out.println("ERROR-02:" + e.getMessage());
}
You must change the security settings for java applets first. By default, java applets cannot print.
Make sure that printer.conf defines <DefaultPrinter name> instead of <Printer name>. JVM seems to only find a default printer that is defined like this.
This code snippet could help out to quickly verify if it works:
import javax.print.PrintServiceLookup;
public class checkDefaultPrinter {
public static void main(String[] args) {
System.out.println(PrintServiceLookup.lookupDefaultPrintService());
}
}
In windows, make sure the Print Spooler service is running. Also, You can test this code while applying the solution
import javax.print.PrintService;
import javax.print.PrintServiceLookup;
public class JavaPrintBug {
public static void main(String[] args) {
// returns an empty array unless a user has opened system printer settings
// only short time ago or an adminstrator has set cupsctl WebInterface=yes
PrintService[] printServices = PrintServiceLookup.lookupPrintServices(null, null);
System.out.println("Number of printers available: " + printServices.length); // zero
// returns null unless a user has opened system printer settings only
// short time ago or an adminstrator has set cupsctl WebInterface=yes
PrintService defaultPrintService = PrintServiceLookup.lookupDefaultPrintService();
if(null != defaultPrintService) { // will not be entered
System.out.println("Default printer: " + defaultPrintService.getName());
}
// before entering this loop make sure that NO user has opened system
// printer settings only short time ago and NO administrator has set
// cupsctl WebInterface=yes (hWebInterface=no)!
while(null == PrintServiceLookup.lookupDefaultPrintService()) {
// while trapped in here, open system printer settings or set
// cupsctl WebInterface=yes and the loop will be left.
// In Windows, enable the Print Spooler service
}
System.out.println("Workaround worked!");
}
}
Reference: https://bugs.openjdk.org/browse/JDK-8178715
Related
I'm a Java programer from China, recently I found a strange thing that the Windows console (eg. cmd.exe) seems to be able to display the characters that are not supported by current Code Page.
Could someone please tell me why?
There is example code and test result below.
import java.io.*;
import java.nio.charset.Charset;
public class EncodingTest {
public static void main(String[] args) {
System.out.println("jvm default charset:" + Charset.defaultCharset());
System.out.println(System.getProperty("file.encoding"));
PrintStream ps = new PrintStream(System.out, true);
ps.println("PrintStream测试");
System.out.println("测试哦，就是要测试啊啊");
System.out.println("中文测试");
System.out.println("--------------");
}
}
and here is screenshot of test result:
Screenshot
In Java, I'm dynamically creating a set of files and I'd like to change the file permissions on these files on a linux/unix file system. I'd like to be able to execute the Java equivalent of chmod. Is that possible Java 5? If so, how?
I know in Java 6 the File object has setReadable()/setWritable() methods. I also know I could make a system call to do this, but I'd like to avoid that if possible.
Full control over file attributes is available in Java 7, as part of the "new" New IO facility (NIO.2). For example, POSIX permissions can be set on an existing file with setPosixFilePermissions(), or atomically at file creation with methods like createFile() or newByteChannel().
You can create a set of permissions using EnumSet.of(), but the helper method PosixFilePermissions.fromString() will uses a conventional format that will be more readable to many developers. For APIs that accept a FileAttribute, you can wrap the set of permissions with with PosixFilePermissions.asFileAttribute().
Set<PosixFilePermission> ownerWritable = PosixFilePermissions.fromString("rw-r--r--");
FileAttribute<?> permissions = PosixFilePermissions.asFileAttribute(ownerWritable);
Files.createFile(path, permissions);
In earlier versions of Java, using native code of your own, or exec-ing command-line utilities are common approaches.
Prior to Java 6, there is no support of file permission update at Java level. You have to implement your own native method or call Runtime.exec() to execute OS level command such as chmod.
Starting from Java 6, you can useFile.setReadable()/File.setWritable()/File.setExecutable() to set file permissions. But it doesn't simulate the POSIX file system which allows to set permission for different users. File.setXXX() only allows to set permission for owner and everyone else.
Starting from Java 7, POSIX file permission is introduced. You can set file permissions like what you have done on *nix systems. The syntax is :
File file = new File("file4.txt");
file.createNewFile();
Set<PosixFilePermission> perms = new HashSet<>();
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_WRITE);
Files.setPosixFilePermissions(file.toPath(), perms);
This method can only be used on POSIX file system, this means you cannot call it on Windows system.
For details on file permission management, recommend you to read this post.
In addition to erickson's suggestions, there's also jna, which allows you to call native libraries without using jni. It's shockingly easy to use, and I've used it on a couple of projects with great success.
The only caveat is that it's slower than jni, so if you're doing this to a very large number of files that might be an issue for you.
(Editing to add example)
Here's a complete jna chmod example:
import com.sun.jna.Library;
import com.sun.jna.Native;
public class Main {
private static CLibrary libc = (CLibrary) Native.loadLibrary("c", CLibrary.class);
public static void main(String[] args) {
libc.chmod("/path/to/file", 0755);
}
}
interface CLibrary extends Library {
public int chmod(String path, int mode);
}
For Windows 7 with NIO 2:
public static void main(String[] args) throws IOException {
Path file = Paths.get("c:/touch.txt");
AclFileAttributeView aclAttr = Files.getFileAttributeView(file, AclFileAttributeView.class);
System.out.println(aclAttr.getOwner());
for (AclEntry aclEntry : aclAttr.getAcl()) {
System.out.println(aclEntry);
}
System.out.println();
UserPrincipalLookupService upls = file.getFileSystem().getUserPrincipalLookupService();
UserPrincipal user = upls.lookupPrincipalByName(System.getProperty("user.name"));
AclEntry.Builder builder = AclEntry.newBuilder();
builder.setPermissions( EnumSet.of(AclEntryPermission.READ_DATA, AclEntryPermission.EXECUTE,
AclEntryPermission.READ_ACL, AclEntryPermission.READ_ATTRIBUTES, AclEntryPermission.READ_NAMED_ATTRS,
AclEntryPermission.WRITE_ACL, AclEntryPermission.DELETE
));
builder.setPrincipal(user);
builder.setType(AclEntryType.ALLOW);
aclAttr.setAcl(Collections.singletonList(builder.build()));
}
Just to update this answer unless anyone comes across this later, since JDK 6 you can use
File file = new File('/directory/to/file');
file.setWritable(boolean);
file.setReadable(boolean);
file.setExecutable(boolean);
you can find the documentation on Oracle File(Java Platform SE 7). Bear in mind that these commands only work if the current working user has ownership or write access to that file. I am aware that OP wanted chmod type access for more intricate user configuration. these will set the option across the board for all users.
If you want to set 777 permission to your created file than you can use the following method:
public void setPermission(File file) throws IOException{
Set<PosixFilePermission> perms = new HashSet<>();
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_WRITE);
perms.add(PosixFilePermission.OWNER_EXECUTE);
perms.add(PosixFilePermission.OTHERS_READ);
perms.add(PosixFilePermission.OTHERS_WRITE);
perms.add(PosixFilePermission.OTHERS_EXECUTE);
perms.add(PosixFilePermission.GROUP_READ);
perms.add(PosixFilePermission.GROUP_WRITE);
perms.add(PosixFilePermission.GROUP_EXECUTE);
Files.setPosixFilePermissions(file.toPath(), perms);
}
You can use the methods of the File class:
http://docs.oracle.com/javase/7/docs/api/java/io/File.html
Apache ant chmod (not very elegant, adding it for completeness) credit shared with #msorsky
Chmod chmod = new Chmod();
chmod.setProject(new Project());
FileSet mySet = new FileSet();
mySet.setDir(new File("/my/path"));
mySet.setIncludes("**");
chmod.addFileset(mySet);
chmod.setPerm("+w");
chmod.setType(new FileDirBoth());
chmod.execute();
for Oralce Java 6:
private static int chmod(String filename, int mode) {
try {
Class<?> fspClass = Class.forName("java.util.prefs.FileSystemPreferences");
Method chmodMethod = fspClass.getDeclaredMethod("chmod", String.class, Integer.TYPE);
chmodMethod.setAccessible(true);
return (Integer)chmodMethod.invoke(null, filename, mode);
} catch (Throwable ex) {
return -1;
}
}
works under solaris/linux.
There is an example class on Oracle Docs which works very much similar to the UNIX chmod. It works with java se 7+ though.
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFileAttributes;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;
public class FileAndDirectory1 {
public static void main(String[] args) {
File file = new File("fileTest1.txt");
System.out.println(file.getAbsoluteFile());
try {
//file.createNewFile();
if(!file.exists())
{
//PosixFilePermission is an enum class, PosixFilePermissions is a final class
//create file permissions from string
Set<PosixFilePermission> filePermissions = PosixFilePermissions.fromString("---------"/* "rwxrwxrwx" */);
FileAttribute<?> permissions = PosixFilePermissions.asFileAttribute(filePermissions);
Files.createFile(file.toPath(), permissions);
// printing the permissions associated with the file
System.out.println("Executable: " + file.canExecute());
System.out.println("Readable: " + file.canRead());
System.out.println("Writable: "+ file.canWrite());
file.setExecutable(true);
file.setReadable(true);
file.setWritable(true);
}
else
{
//modify permissions
//get the permission using file attributes
Set<PosixFilePermission> perms = Files.readAttributes(file.toPath(), PosixFileAttributes.class).permissions();
perms.remove(PosixFilePermission.OWNER_WRITE);
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_EXECUTE);
perms.add(PosixFilePermission.GROUP_WRITE);
perms.add(PosixFilePermission.GROUP_READ);
perms.add(PosixFilePermission.GROUP_EXECUTE);
perms.add(PosixFilePermission.OTHERS_WRITE);
perms.add(PosixFilePermission.OTHERS_READ);
perms.add(PosixFilePermission.OTHERS_EXECUTE);
Files.setPosixFilePermissions(file.toPath(), perms);
System.out.println("Executable: " + file.canExecute());
System.out.println("Readable: " + file.canRead());
System.out.println("Writable: "+ file.canWrite());
file.delete();
}
} catch (IOException e) {
e.printStackTrace();
}
Path path = Paths.get(String.valueOf(file));
System.out.println(path);
}
}
Permission 777 is the same as rwxrwxrwx which you can set as follows:
Files.setPosixFilePermissions(path, PosixFilePermissions.fromString("rwxrwxrwx"))
I have problem with Java print service. I need to print a simple text document, to my default printer. I use HP Deskjet as my printer on Windows machine, all driver installed. This is the source code I use:
import java.io.*;
import javax.print.*;
public class PrintTest {
public static void main(String[] args) throws IOException {
File file = new File("print.txt");
InputStream is = new BufferedInputStream(new FileInputStream(file));
//Discover the default print service.
PrintService service = PrintServiceLookup.lookupDefaultPrintService();
//Doc flavor specifies the output format of the file.
DocFlavor flavor = DocFlavor.INPUT_STREAM.AUTOSENSE;
// Create the print job
DocPrintJob job = service.createPrintJob();
//Create the Doc
Doc doc = new SimpleDoc(is, flavor, null);
//Order to print
try {
job.print(doc, null);
} catch (PrintException e) {
e.printStackTrace();
}
is.close();
System.out.println("Printing done....");
}
}
I can see the print job on printer queue for several milisecond before its gone. But nothing get printed. I have heard it's because Java Print Service in JDK 1.6 is still buggy. But I'm not entirely sure. Any ideas why?
I know it is a very late answer but I had the same problem on Windows with PDFs (not text). It seems that printers may not be able to deal with native PDFs, so the job is accepted but nothing happens (no error too). I solved this by using a third-party lib, Apache PdfBox, and it worked like a charm.
I wrote some code example by answering a similar question https://stackoverflow.com/a/39271053/935039.
I want a java program for windows in which I can also send the print specification like Layout Orientation,Number of copies,Pages from and to,etc along with the file path to be printed.
M using This Code ,It works bt I can't provide the print Specifications?
import java.awt.Desktop;
import java.io.File;
import java.io.IOException;
public class PrintFile {
public static void fileToPrint(File fis) {
try {
Desktop desktop = null;
if (Desktop.isDesktopSupported())
{
desktop = Desktop.getDesktop();
}
desktop.print(fis);
System.out.print("Printing Document");
}
catch (IOException ioe)
{
ioe.printStackTrace();
}
}
}
Check out Java Print Service API
The javax.print.attribute and javax.print.attribute.standard packages define print attributes which describe the capabilities of a print service, specify the requirements of a print job, and track the progress of the print job.
For example, if you would like to use A4 paper format and print three copies of your document you will have to create a set of the following attributes implementing the PrintRequestAttributeSet interface:
PrintRequestAttributeSet attr_set = new HashPrintRequestAttributeSet();
attr_set.add(MediaSizeName.ISO_A4);
attr_set.add(new Copies(3));
Then you must pass the attribute set to the print job's print method, along with the DocFlavor.
MediaSize.ISO.A4 or MediaSize.ISO_A4 doesn't work. Instead MediaSizeName.ISO_A4 is correct.
In Java, I'm dynamically creating a set of files and I'd like to change the file permissions on these files on a linux/unix file system. I'd like to be able to execute the Java equivalent of chmod. Is that possible Java 5? If so, how?
I know in Java 6 the File object has setReadable()/setWritable() methods. I also know I could make a system call to do this, but I'd like to avoid that if possible.
Full control over file attributes is available in Java 7, as part of the "new" New IO facility (NIO.2). For example, POSIX permissions can be set on an existing file with setPosixFilePermissions(), or atomically at file creation with methods like createFile() or newByteChannel().
You can create a set of permissions using EnumSet.of(), but the helper method PosixFilePermissions.fromString() will uses a conventional format that will be more readable to many developers. For APIs that accept a FileAttribute, you can wrap the set of permissions with with PosixFilePermissions.asFileAttribute().
Set<PosixFilePermission> ownerWritable = PosixFilePermissions.fromString("rw-r--r--");
FileAttribute<?> permissions = PosixFilePermissions.asFileAttribute(ownerWritable);
Files.createFile(path, permissions);
In earlier versions of Java, using native code of your own, or exec-ing command-line utilities are common approaches.
Prior to Java 6, there is no support of file permission update at Java level. You have to implement your own native method or call Runtime.exec() to execute OS level command such as chmod.
Starting from Java 6, you can useFile.setReadable()/File.setWritable()/File.setExecutable() to set file permissions. But it doesn't simulate the POSIX file system which allows to set permission for different users. File.setXXX() only allows to set permission for owner and everyone else.
Starting from Java 7, POSIX file permission is introduced. You can set file permissions like what you have done on *nix systems. The syntax is :
File file = new File("file4.txt");
file.createNewFile();
Set<PosixFilePermission> perms = new HashSet<>();
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_WRITE);
Files.setPosixFilePermissions(file.toPath(), perms);
This method can only be used on POSIX file system, this means you cannot call it on Windows system.
For details on file permission management, recommend you to read this post.
In addition to erickson's suggestions, there's also jna, which allows you to call native libraries without using jni. It's shockingly easy to use, and I've used it on a couple of projects with great success.
The only caveat is that it's slower than jni, so if you're doing this to a very large number of files that might be an issue for you.
(Editing to add example)
Here's a complete jna chmod example:
import com.sun.jna.Library;
import com.sun.jna.Native;
public class Main {
private static CLibrary libc = (CLibrary) Native.loadLibrary("c", CLibrary.class);
public static void main(String[] args) {
libc.chmod("/path/to/file", 0755);
}
}
interface CLibrary extends Library {
public int chmod(String path, int mode);
}
For Windows 7 with NIO 2:
public static void main(String[] args) throws IOException {
Path file = Paths.get("c:/touch.txt");
AclFileAttributeView aclAttr = Files.getFileAttributeView(file, AclFileAttributeView.class);
System.out.println(aclAttr.getOwner());
for (AclEntry aclEntry : aclAttr.getAcl()) {
System.out.println(aclEntry);
}
System.out.println();
UserPrincipalLookupService upls = file.getFileSystem().getUserPrincipalLookupService();
UserPrincipal user = upls.lookupPrincipalByName(System.getProperty("user.name"));
AclEntry.Builder builder = AclEntry.newBuilder();
builder.setPermissions( EnumSet.of(AclEntryPermission.READ_DATA, AclEntryPermission.EXECUTE,
AclEntryPermission.READ_ACL, AclEntryPermission.READ_ATTRIBUTES, AclEntryPermission.READ_NAMED_ATTRS,
AclEntryPermission.WRITE_ACL, AclEntryPermission.DELETE
));
builder.setPrincipal(user);
builder.setType(AclEntryType.ALLOW);
aclAttr.setAcl(Collections.singletonList(builder.build()));
}
Just to update this answer unless anyone comes across this later, since JDK 6 you can use
File file = new File('/directory/to/file');
file.setWritable(boolean);
file.setReadable(boolean);
file.setExecutable(boolean);
you can find the documentation on Oracle File(Java Platform SE 7). Bear in mind that these commands only work if the current working user has ownership or write access to that file. I am aware that OP wanted chmod type access for more intricate user configuration. these will set the option across the board for all users.
If you want to set 777 permission to your created file than you can use the following method:
public void setPermission(File file) throws IOException{
Set<PosixFilePermission> perms = new HashSet<>();
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_WRITE);
perms.add(PosixFilePermission.OWNER_EXECUTE);
perms.add(PosixFilePermission.OTHERS_READ);
perms.add(PosixFilePermission.OTHERS_WRITE);
perms.add(PosixFilePermission.OTHERS_EXECUTE);
perms.add(PosixFilePermission.GROUP_READ);
perms.add(PosixFilePermission.GROUP_WRITE);
perms.add(PosixFilePermission.GROUP_EXECUTE);
Files.setPosixFilePermissions(file.toPath(), perms);
}
You can use the methods of the File class:
http://docs.oracle.com/javase/7/docs/api/java/io/File.html
Apache ant chmod (not very elegant, adding it for completeness) credit shared with #msorsky
Chmod chmod = new Chmod();
chmod.setProject(new Project());
FileSet mySet = new FileSet();
mySet.setDir(new File("/my/path"));
mySet.setIncludes("**");
chmod.addFileset(mySet);
chmod.setPerm("+w");
chmod.setType(new FileDirBoth());
chmod.execute();
import java.io.File;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.FileAttribute;
import java.nio.file.attribute.PosixFileAttributes;
import java.nio.file.attribute.PosixFilePermission;
import java.nio.file.attribute.PosixFilePermissions;
import java.util.Set;
public class FileAndDirectory1 {
public static void main(String[] args) {
File file = new File("fileTest1.txt");
System.out.println(file.getAbsoluteFile());
try {
//file.createNewFile();
if(!file.exists())
{
//PosixFilePermission is an enum class, PosixFilePermissions is a final class
//create file permissions from string
Set<PosixFilePermission> filePermissions = PosixFilePermissions.fromString("---------"/* "rwxrwxrwx" */);
FileAttribute<?> permissions = PosixFilePermissions.asFileAttribute(filePermissions);
Files.createFile(file.toPath(), permissions);
// printing the permissions associated with the file
System.out.println("Executable: " + file.canExecute());
System.out.println("Readable: " + file.canRead());
System.out.println("Writable: "+ file.canWrite());
file.setExecutable(true);
file.setReadable(true);
file.setWritable(true);
}
else
{
//modify permissions
//get the permission using file attributes
Set<PosixFilePermission> perms = Files.readAttributes(file.toPath(), PosixFileAttributes.class).permissions();
perms.remove(PosixFilePermission.OWNER_WRITE);
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_EXECUTE);
perms.add(PosixFilePermission.GROUP_WRITE);
perms.add(PosixFilePermission.GROUP_READ);
perms.add(PosixFilePermission.GROUP_EXECUTE);
perms.add(PosixFilePermission.OTHERS_WRITE);
perms.add(PosixFilePermission.OTHERS_READ);
perms.add(PosixFilePermission.OTHERS_EXECUTE);
Files.setPosixFilePermissions(file.toPath(), perms);
System.out.println("Executable: " + file.canExecute());
System.out.println("Readable: " + file.canRead());
System.out.println("Writable: "+ file.canWrite());
file.delete();
}
} catch (IOException e) {
e.printStackTrace();
}
Path path = Paths.get(String.valueOf(file));
System.out.println(path);
}
}
for Oralce Java 6:
private static int chmod(String filename, int mode) {
try {
Class<?> fspClass = Class.forName("java.util.prefs.FileSystemPreferences");
Method chmodMethod = fspClass.getDeclaredMethod("chmod", String.class, Integer.TYPE);
chmodMethod.setAccessible(true);
return (Integer)chmodMethod.invoke(null, filename, mode);
} catch (Throwable ex) {
return -1;
}
}
works under solaris/linux.
There is an example class on Oracle Docs which works very much similar to the UNIX chmod. It works with java se 7+ though.
Permission 777 is the same as rwxrwxrwx which you can set as follows:
Files.setPosixFilePermissions(path, PosixFilePermissions.fromString("rwxrwxrwx"))