How is it possible to read/write to the Windows registry using Java?
You don't actually need a 3rd party package. Windows has a reg utility for all registry operations. To get the command format, go to the DOS propmt and type:
reg /?
You can invoke reg through the Runtime class:
Runtime.getRuntime().exec("reg ");
Editing keys and adding new ones is straightforward using the command above. To read the registry, you need to get reg's output, and it's a little tricky. Here's the code:
import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
/**
* @author Oleg Ryaboy, based on work by Miguel Enriquez
*/
public class WindowsReqistry {
/**
*
* @param location path in the registry
* @param key registry key
* @return registry value or null if not found
*/
public static final String readRegistry(String location, String key){
try {
// Run reg query, then read output with StreamReader (internal class)
Process process = Runtime.getRuntime().exec("reg query " +
'"'+ location + "\" /v " + key);
StreamReader reader = new StreamReader(process.getInputStream());
reader.start();
process.waitFor();
reader.join();
String output = reader.getResult();
// Output has the following format:
// \n\n\n\t\t
if( ! output.contains("\t")){
return null;
}
// Parse out the value
String[] parsed = output.split("\t");
return parsed[parsed.length-1];
}
catch (Exception e) {
return null;
}
}
static class StreamReader extends Thread {
private InputStream is;
private StringWriter sw= new StringWriter();
public StreamReader(InputStream is) {
this.is = is;
}
public void run() {
try {
int c;
while ((c = is.read()) != -1)
sw.write(c);
}
catch (IOException e) {
}
}
public String getResult() {
return sw.toString();
}
}
public static void main(String[] args) {
// Sample usage
String value = WindowsReqistry.readRegistry("HKCU\\Software\\Microsoft\\Windows\\CurrentVersion\\"
+ "Explorer\\Shell Folders", "Personal");
System.out.println(value);
}
}