Read/write to Windows registry using Java

Question

How is it possible to read/write to the Windows registry using Java?

Answer 1

This was crazy... I took the code from one of the posts here, failed to see there were 18 more comments in which one stated that it does not read a dword value...

In any case, I've refactored the hell of that code into something with less ifs and methods...

The Enum could be refined a bit, but as soon as I've fought my way to read a numeric value or byte array and failed, I've given up...

So here it is:

package com.nu.art.software.utils;


import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.List;
import java.util.prefs.Preferences;

/**
 *
 * @author TacB0sS
 */
public class WinRegistry_TacB0sS {

    public static final class RegistryException
            extends Exception {

        private static final long serialVersionUID = -8799947496460994651L;

        public RegistryException(String message, Throwable e) {
            super(message, e);
        }

        public RegistryException(String message) {
            super(message);
        }


    }

    public static final int KEY_WOW64_32KEY = 0x0200;

    public static final int KEY_WOW64_64KEY = 0x0100;

    public static final int REG_SUCCESS = 0;

    public static final int REG_NOTFOUND = 2;

    public static final int REG_ACCESSDENIED = 5;

    private static final int KEY_ALL_ACCESS = 0xf003f;

    private static final int KEY_READ = 0x20019;

    public enum WinRegistryKey {
        User(Preferences.userRoot(), 0x80000001), ;

        // System(Preferences.systemRoot(), 0x80000002);

        private final Preferences preferencesRoot;

        private final Integer key;

        private WinRegistryKey(Preferences preferencesRoot, int key) {
            this.preferencesRoot = preferencesRoot;
            this.key = key;
        }
    }

    private enum WinRegistryMethod {
        OpenKey("WindowsRegOpenKey", int.class, byte[].class, int.class) {

            @Override
            protected void verifyReturnValue(Object retValue)
                    throws RegistryException {
                int[] retVal = (int[]) retValue;
                if (retVal[1] != REG_SUCCESS)
                    throw new RegistryException("Action Failed, Return Code: " + retVal[1]);
            }
        },
        CreateKeyEx("WindowsRegCreateKeyEx", int.class, byte[].class) {

            @Override
            protected void verifyReturnValue(Object retValue)
                    throws RegistryException {
                int[] retVal = (int[]) retValue;
                if (retVal[1] != REG_SUCCESS)
                    throw new RegistryException("Action Failed, Return Code: " + retVal[1]);
            }
        },
        DeleteKey("WindowsRegDeleteKey", int.class, byte[].class) {

            @Override
            protected void verifyReturnValue(Object retValue)
                    throws RegistryException {
                int retVal = ((Integer) retValue).intValue();
                if (retVal != REG_SUCCESS)
                    throw new RegistryException("Action Failed, Return Code: " + retVal);
            }
        },
        DeleteValue("WindowsRegDeleteValue", int.class, byte[].class) {

            @Override
            protected void verifyReturnValue(Object retValue)
                    throws RegistryException {
                int retVal = ((Integer) retValue).intValue();
                if (retVal != REG_SUCCESS)
                    throw new RegistryException("Action Failed, Return Code: " + retVal);
            }
        },
        CloseKey("WindowsRegCloseKey", int.class),
        QueryValueEx("WindowsRegQueryValueEx", int.class, byte[].class),
        EnumKeyEx("WindowsRegEnumKeyEx", int.class, int.class, int.class),
        EnumValue("WindowsRegEnumValue", int.class, int.class, int.class),
        QueryInfoKey("WindowsRegQueryInfoKey", int.class),
        SetValueEx("WindowsRegSetValueEx", int.class, byte[].class, byte[].class);

        private Method method;

        private WinRegistryMethod(String methodName, Class... classes) {
            // WinRegistryKey.User.preferencesRoot.getClass().getMDeclaredMethods()
            try {
                method = WinRegistryKey.User.preferencesRoot.getClass().getDeclaredMethod(methodName, classes);
            } catch (Exception e) {
                System.err.println("Error");
                System.err.println(e);
            }
            method.setAccessible(true);
        }

        public Object invoke(Preferences root, Object... objects)
                throws RegistryException {
            Object retValue;
            try {
                retValue = method.invoke(root, objects);
                verifyReturnValue(retValue);
            } catch (Throwable e) {
                String params = "";
                if (objects.length > 0) {
                    params = objects[0].toString();
                    for (int i = 1; i < objects.length; i++) {
                        params += ", " + objects[i];
                    }
                }
                throw new RegistryException("Error invoking method: " + method + ", with params: (" + params + ")", e);
            }
            return retValue;
        }

        protected void verifyReturnValue(Object retValue)
                throws RegistryException {}
    }

    private WinRegistry_TacB0sS() {}

    public static String readString(WinRegistryKey regKey, String key, String valueName)
            throws RegistryException {
        int retVal = ((int[]) WinRegistryMethod.OpenKey.invoke(regKey.preferencesRoot, regKey.key, toCstr(key),
                new Integer(KEY_READ)))[0];

        byte[] retValue = (byte[]) WinRegistryMethod.QueryValueEx.invoke(regKey.preferencesRoot, retVal,
                toCstr(valueName));
        WinRegistryMethod.CloseKey.invoke(regKey.preferencesRoot, retVal);

        /*
         * Should this return an Empty String.
         */
        return (retValue != null ? new String(retValue).trim() : null);
    }

    public static Map readStringValues(WinRegistryKey regKey, String key)
            throws RegistryException {
        HashMap results = new HashMap();
        int retVal = ((int[]) WinRegistryMethod.OpenKey.invoke(regKey.preferencesRoot, regKey.key, toCstr(key),
                new Integer(KEY_READ)))[0];

        int[] info = (int[]) WinRegistryMethod.QueryInfoKey.invoke(regKey.preferencesRoot, retVal);

        int count = info[2]; // count
        int maxlen = info[3]; // value length max
        for (int index = 0; index < count; index++) {
            byte[] name = (byte[]) WinRegistryMethod.EnumValue.invoke(regKey.preferencesRoot, retVal,
                    new Integer(index), new Integer(maxlen + 1));
            String value = readString(regKey, key, new String(name));
            results.put(new String(name).trim(), value);
        }

        WinRegistryMethod.CloseKey.invoke(regKey.preferencesRoot, retVal);
        return results;
    }

    public static List readStringSubKeys(WinRegistryKey regKey, String key)
            throws RegistryException {
        List results = new ArrayList();
        int retVal = ((int[]) WinRegistryMethod.OpenKey.invoke(regKey.preferencesRoot, regKey.key, toCstr(key),
                new Integer(KEY_READ)))[0];

        int[] info = (int[]) WinRegistryMethod.QueryInfoKey.invoke(regKey.preferencesRoot, retVal);

        int count = info[0]; // Fix: info[2] was being used here with wrong results. Suggested by davenpcj, confirmed by
                                // Petrucio
        int maxlen = info[3]; // value length max
        for (int index = 0; index < count; index++) {
            byte[] name = (byte[]) WinRegistryMethod.EnumValue.invoke(regKey.preferencesRoot, retVal,
                    new Integer(index), new Integer(maxlen + 1));
            results.add(new String(name).trim());
        }

        WinRegistryMethod.CloseKey.invoke(regKey.preferencesRoot, retVal);
        return results;
    }

    public static void createKey(WinRegistryKey regKey, String key)
            throws RegistryException {
        int[] retVal = (int[]) WinRegistryMethod.CreateKeyEx.invoke(regKey.preferencesRoot, regKey.key, toCstr(key));
        WinRegistryMethod.CloseKey.invoke(regKey.preferencesRoot, retVal[0]);
    }

    public static void writeStringValue(WinRegistryKey regKey, String key, String valueName, String value)
            throws RegistryException {
        int retVal = ((int[]) WinRegistryMethod.OpenKey.invoke(regKey.preferencesRoot, regKey.key, toCstr(key),
                new Integer(KEY_ALL_ACCESS)))[0];

        WinRegistryMethod.SetValueEx.invoke(regKey.preferencesRoot, retVal, toCstr(valueName), toCstr(value));
        WinRegistryMethod.CloseKey.invoke(regKey.preferencesRoot, retVal);
    }

    public static void deleteKey(WinRegistryKey regKey, String key)
            throws RegistryException {
        WinRegistryMethod.DeleteKey.invoke(regKey.preferencesRoot, regKey.key, toCstr(key));
    }

    public static void deleteValue(WinRegistryKey regKey, String key, String value)
            throws RegistryException {
        int retVal = ((int[]) WinRegistryMethod.OpenKey.invoke(regKey.preferencesRoot, regKey.key, toCstr(key),
                new Integer(KEY_ALL_ACCESS)))[0];
        WinRegistryMethod.DeleteValue.invoke(regKey.preferencesRoot, retVal, toCstr(value));
        WinRegistryMethod.CloseKey.invoke(regKey.preferencesRoot, retVal);
    }

    // utility
    private static byte[] toCstr(String str) {
        byte[] result = new byte[str.length() + 1];

        for (int i = 0; i < str.length(); i++) {
            result[i] = (byte) str.charAt(i);
        }
        result[str.length()] = '\0';
        return result;
    }
}

NOTE: THIS DOES NOT READ ANYTHING ELSE BUT STRINGS!!!!!