如何在Java中获取JAVA_HOME和CATALINA_HOME环境变量？

Question

我需要在 Java 中获取 JAVA_HOME 和 CATALINA_HOME 环境变量的值。我是运行一个 JAR（不是 WAR），在 System.getProperties() 中我只能找到 "java.home"。

我在这里阅读了一些关于它的其他问题，尝试了它们，但无法使它们工作 - 我得到了不同的异常或结果只是 null 值。

我记得很多年前用JNA做过类似的事情，但那是在Windows的16位时代。我能找到的最新 JNA jar 是从 2011 年开始的，运行它在 intelliJ 中有效，但是当我在 maven 中构建时，我得到关于找不到一些 classes.

我将继续研究 JNA 方向，很高兴收到任何帮助 and/or 想法。我认为我只是缺少正确的 Maven 依赖项.

这是我 class 到目前为止的源代码：

//  C:\devtools\java-external-jars\jna-4.2.2\jna-platform-4.2.2.jar

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

import java.io.IOException;
import java.io.InputStream;
import java.io.StringWriter;
import java.lang.reflect.InvocationTargetException;
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;

public class WinRegistryHelper {

    public static final String SYSTEM_ENVIRONMENT_KEY_PATH = "SYSTEM\ControlSet001\Control\Session Manager\Environment";

    public static final int HKEY_CURRENT_USER = 0x80000001;
    public static final int HKEY_LOCAL_MACHINE = 0x80000002;
    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;
    private static final Preferences userRoot = Preferences.userRoot();
    private static final Preferences systemRoot = Preferences.systemRoot();
    private static final Class<? extends Preferences> userClass = userRoot.getClass();
    private static final Method regOpenKey;
    private static final Method regCloseKey;
    private static final Method regQueryValueEx;
    private static final Method regEnumValue;
    private static final Method regQueryInfoKey;
    private static final Method regEnumKeyEx;
    private static final Method regCreateKeyEx;
    private static final Method regSetValueEx;
    private static final Method regDeleteKey;
    private static final Method regDeleteValue;

    private WinRegistryHelper() {  }


    /**
     *
     * {@code String stringValue = Advapi32Util.registryGetStringValue(WinReg.HKEY_LOCAL_MACHINE, "SOFTWARE\Microsoft\Windows NT\CurrentVersion", "ProductName");}
     */
    public static String registryGetStringValue(WinReg.HKEY root, String keyPath, String keyName) {
        // Read a string
        String stringValue = Advapi32Util.registryGetStringValue(root, keyPath, keyName);
        System.out.printf(keyName + " value is: %s\n", stringValue);
        return stringValue;
    }

    /**
     *
     * {@code int timeout = Advapi32Util.registryGetIntValue(WinReg.HKEY_LOCAL_MACHINE, "SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows", "ShutdownWarningDialogTimeout");}
     */
    public static int registryGetIntValue(WinReg.HKEY root, String keyPath, String keyName) {
        // Read an int (& 0xFFFFFFFFL for large unsigned int)
        int intValue = Advapi32Util.registryGetIntValue(root, keyPath, keyName);
        System.out.printf(keyName + " value is: %d (%d as unsigned long)\n", intValue, intValue & 0xFFFFFFFFL);
        return intValue;
    }

    /**
     *
     * {@code int timeout = Advapi32Util.registryGetLongValue(WinReg.HKEY_LOCAL_MACHINE, "SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows", "ShutdownWarningDialogTimeout");}
     */
    public static long registryGetLongValue(WinReg.HKEY root, String keyPath, String keyName) {
        // Read an int (& 0xFFFFFFFFL for large unsigned int)
        long longValue = Advapi32Util.registryGetLongValue(root, keyPath, keyName);
        System.out.printf(keyName + " value is: %d (%d as unsigned long)\n", longValue, longValue & 0xFFFFFFFFL);
        return longValue;
    }

    /**
     *
     * {@code Advapi32Util.registryCreateKeyPath(WinReg.HKEY_CURRENT_USER, "SOFTWARE\Whosebug");}
     */
    public static void registryCreateKeyPath(WinReg.HKEY root, String keyPath) {
        // Create a key and write a string
        Advapi32Util.registryCreateKey(root, keyPath);
    }

    /**
     * {@code Advapi32Util.registrySetStringValue(WinReg.HKEY_CURRENT_USER, "SOFTWARE\Whosebug", "url", "");}
     */
    public static void registrySetStringValue(WinReg.HKEY root, String keyPath, String keyName, String keyValue) {
        Advapi32Util.registrySetStringValue(root, keyPath, keyName, keyValue);
    }

    public static void registrySetIntValue(WinReg.HKEY root, String keyPath, String keyName, int keyValue) {
        Advapi32Util.registrySetIntValue(root, keyPath, keyName, keyValue);
    }

    public static void registrySetLongValue(WinReg.HKEY root, String keyPath, String keyName, long keyValue) {
        Advapi32Util.registrySetLongValue(root, keyPath, keyName, keyValue);
    }

    /**
     *
     * {@code Advapi32Util.registryDeleteKey(WinReg.HKEY_CURRENT_USER, "SOFTWARE\Whosebug");}
     */
    public static void registryDeleteKey(WinReg.HKEY root, String keyPath) {
        // Delete a key
        Advapi32Util.registryDeleteKey(root, keyPath);
    }
}

Answer 1

有一个System.getenv方法可以帮助获取指定环境变量的值：

System.getenv("JAVA_HOME");
System.getenv("CATALINA_HOME");

如果安全管理器允许访问环境变量。否则，将抛出 SecurityException。

Answer 2

Tomcat主目录或Catalina目录存放在Java系统属性环境中。如果Java web 应用程序部署到Tomcat web 服务器，我们可以使用以下命令

获取Tomcat 目录

System.out.println(System.getProperty("catalina.base"));
System.out.println(System.getProperty("catalina.home"));

//you can store it in string
String caltelinaHome =System.getProperty("catalina.home");

如何在Java中获取JAVA_HOME和CATALINA_HOME环境变量？

How to get JAVA_HOME and CATALINA_HOME environment variables in Java?

java

environment-variables

jna

java-home