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Read/Write Windows Registry using JNATag(s): Environment JNA


JNA (Java Native Access) provides Java programs easy access to native shared libraries (DLLs on Windows) without writing anything but Java code - no JNI or native code is required.

In previous HowTo, we were accessing the registry using the REG.EXE utility or hacking the Preferences class. This HowTo with JNA is lot cleaner.

The package com.sun.jna.platform.win32.Advapi32Util gives a simple interface to manipulates the registry.

Be careful, Windows registry is a sensitive thing. Modification to the registry can cause serious problems that may require you to reinstall Windows! 




import java.util.Map;



import com.sun.jna.platform.win32.Advapi32Util;

import static com.sun.jna.platform.win32.WinReg.HKEY_CURRENT_USER;

import static com.sun.jna.platform.win32.WinReg.HKEY_LOCAL_MACHINE;



public class Advapi32UtilTest {



    // https://github.com/twall/jna#readme

    //  you need 2 jars : jna-3.5.1.jar and platform-3.5.1.jar



    public static void main(String[] args) {

        System.out.println(Advapi32Util.registryGetStringValue

                (HKEY_CURRENT_USER,

                 "Software\\Microsoft\\Internet Explorer\\Main", "Search Page")

        );

        System.out.println(Advapi32Util.registryGetStringValue

                (HKEY_LOCAL_MACHINE,

                 "Software\\Microsoft\\Windows\\CurrentVersion\\App Paths\\AcroRd32.exe",

                 ""));

        System.out.println(Advapi32Util.registryGetStringValue

                (HKEY_LOCAL_MACHINE,

                 "Software\\Microsoft\\Windows\\CurrentVersion\\App Paths\\AcroRd32.exe",

                 "Path"));

        System.out.println(Advapi32Util.registryGetIntValue

                (HKEY_LOCAL_MACHINE,

                 "Software\\Wow6432Node\\Javasoft\\Java Update\\Policy",

                "Frequency"));

        String [] keys = Advapi32Util.registryGetKeys

                (HKEY_CURRENT_USER,

                 "Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings"

                 );

        for (String key : keys) {

            System.out.println(key);

        }

        Map <String, Object>values = Advapi32Util.registryGetValues

        (HKEY_CURRENT_USER,

         "Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings"

         );

        for (String value : values.keySet()) {

            System.out.println(value);

        }



        System.out.println(Advapi32Util.registryKeyExists(HKEY_CURRENT_USER, "Software\\RealHowTo"));

        Advapi32Util.registryCreateKey(HKEY_CURRENT_USER, "Software\\RealHowTo");

        System.out.println(Advapi32Util.registryKeyExists(HKEY_CURRENT_USER, "Software\\RealHowTo"));

        Advapi32Util.registrySetStringValue

            (HKEY_CURRENT_USER, "Software\\RealHowTo", "url", "http://www.rgagnon.com");

        System.out.println(Advapi32Util.registryValueExists(HKEY_CURRENT_USER, "Software\\RealHowTo", "url"));

        System.out.println(Advapi32Util.registryValueExists(HKEY_CURRENT_USER, "Software\\RealHowTo", "foo"));

    }



}