当可执行文件应该找到 64 位时却找到了 32 位 Java

Question

我正在从 PowerShell 脚本编写一个可执行文件，该脚本需要将正确版本的 Java3D 放到客户端计算机上。通过正确的版本，我的意思是当用户打开 CMD 并输入“java -version”时，它会提供 32 或 64 位。我需要为正确的体系结构选择 dll 文件。

问题是，我找到了一个64位W7系统的测试用例，同时安装了32位和64位JDK。 PATH 环境变量中仅包含 64 位版本。但是，当我运行批处理脚本或可执行文件并 echo java -version 时，会出现 32 位 java。因此，它安装 32 位 dll，当用户转到 cmd 时，它使用 64 位，因此不兼容。

由于 32 位 JDK 不包含在 PATH 变量中，为什么脚本运行 32 位 java 以及它从哪里获取此链接？

Answer 1

Google Chrome 和 Firefox 仍然是 64 位 Windows 操作系统下的 32 位应用程序，因此您可能正在 SysWOW64 下执行它们安装的 32 位 java - 特别是如果您使用在其中之一运行的 Java Web Start 安装应用程序浏览器。

我遇到了完全相同的问题，并且我已经实现了对已安装 java 的系统范围搜索，以便我可以创建一个批处理文件，以正确的位数调用确切的 java.exe。

这就是您所需要的：

/**
 * Java Finder by petrucio@stackoverflow(828681) is licensed under a Creative Commons Attribution 3.0 Unported License.
 * Needs WinRegistry.java. Get it at: https://stackoverflow.com/questions/62289/read-write-to-windows-registry-using-java
 *
 * JavaFinder - Windows-specific classes to search for all installed versions of java on this system
 * Author: petrucio@stackoverflow (828681)
 *****************************************************************************/

import java.util.*;
import java.io.*;

/**
 * Helper class to fetch the stdout and stderr outputs from started Runtime execs
 * Modified from http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html?page=4
 *****************************************************************************/
class RuntimeStreamer extends Thread {
    InputStream is;
    String lines;

    RuntimeStreamer(InputStream is) {
        this.is = is;
        this.lines = "";
    }
    public String contents() {
        return this.lines;
    }

    public void run() {
        try {
            InputStreamReader isr = new InputStreamReader(is);
            BufferedReader    br  = new BufferedReader(isr);
            String line = null;
            while ( (line = br.readLine()) != null) {
                this.lines += line + "\n";
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();  
        }
    }

    /**
     * Execute a command and wait for it to finish
     * @return The resulting stdout and stderr outputs concatenated
     ****************************************************************************/
    public static String execute(String[] cmdArray) {
        try {
            Runtime runtime = Runtime.getRuntime();
            Process proc = runtime.exec(cmdArray);
            RuntimeStreamer outputStreamer = new RuntimeStreamer(proc.getInputStream());
            RuntimeStreamer errorStreamer  = new RuntimeStreamer(proc.getErrorStream());
            outputStreamer.start();
            errorStreamer.start();
            proc.waitFor();
            return outputStreamer.contents() + errorStreamer.contents();
        } catch (Throwable t) {
            t.printStackTrace();
        }
        return null;
    }
    public static String execute(String cmd) {
        String[] cmdArray = { cmd };
        return RuntimeStreamer.execute(cmdArray);
    }
}

/**
 * Helper struct to hold information about one installed java version
 ****************************************************************************/
class JavaInfo {
    public String  path;        //! Full path to java.exe executable file
    public String  version;     //! Version string. "Unkown" if the java process returned non-standard version string
    public boolean is64bits;    //! true for 64-bit javas, false for 32

    /**
     * Calls 'javaPath -version' and parses the results
     * @param javaPath: path to a java.exe executable
     ****************************************************************************/
    public JavaInfo(String javaPath) {
        String versionInfo = RuntimeStreamer.execute( new String[] { javaPath, "-version" } );
        String[] tokens = versionInfo.split("\"");

        if (tokens.length < 2) this.version = "Unkown";
        else this.version = tokens[1];
        this.is64bits = versionInfo.toUpperCase().contains("64-BIT");
        this.path     = javaPath;
    }

    /**
     * @return Human-readable contents of this JavaInfo instance
     ****************************************************************************/
    public String toString() {
        return this.path + ":\n  Version: " + this.version + "\n  Bitness: " + (this.is64bits ? "64-bits" : "32-bits");
    }
}

/**
 * Windows-specific java versions finder
 *****************************************************************************/
public class JavaFinder {

    /**
     * @return: A list of javaExec paths found under this registry key (rooted at HKEY_LOCAL_MACHINE)
     * @param wow64  0 for standard registry access (32-bits for 32-bit app, 64-bits for 64-bits app)
     *               or WinRegistry.KEY_WOW64_32KEY to force access to 32-bit registry view,
     *               or WinRegistry.KEY_WOW64_64KEY to force access to 64-bit registry view
     * @param previous: Insert all entries from this list at the beggining of the results
     *************************************************************************/
    private static List<String> searchRegistry(String key, int wow64, List<String> previous) {
        List<String> result = previous;
        try {
            List<String> entries = WinRegistry.readStringSubKeys(WinRegistry.HKEY_LOCAL_MACHINE, key, wow64);
            for (int i = 0; entries != null && i < entries.size(); i++) {
                String val = WinRegistry.readString(WinRegistry.HKEY_LOCAL_MACHINE, key + "\\" + entries.get(i), "JavaHome", wow64);
                if (!result.contains(val + "\\bin\\java.exe")) {
                    result.add(val + "\\bin\\java.exe");
                }
            }
        } catch (Throwable t) {
            t.printStackTrace();
        }
        return result;
    }

    /**
     * @return: A list of JavaInfo with informations about all javas installed on this machine
     * Searches and returns results in this order:
     *   HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment (32-bits view)
     *   HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Runtime Environment (64-bits view)
     *   HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Development Kit     (32-bits view)
     *   HKEY_LOCAL_MACHINE\SOFTWARE\JavaSoft\Java Development Kit     (64-bits view)
     *   WINDIR\system32
     *   WINDIR\SysWOW64
     ****************************************************************************/
    public static List<JavaInfo> findJavas() {
        List<String> javaExecs = new ArrayList<String>();

        javaExecs = JavaFinder.searchRegistry("SOFTWARE\\JavaSoft\\Java Runtime Environment", WinRegistry.KEY_WOW64_32KEY, javaExecs);
        javaExecs = JavaFinder.searchRegistry("SOFTWARE\\JavaSoft\\Java Runtime Environment", WinRegistry.KEY_WOW64_64KEY, javaExecs);
        javaExecs = JavaFinder.searchRegistry("SOFTWARE\\JavaSoft\\Java Development Kit",     WinRegistry.KEY_WOW64_32KEY, javaExecs);
        javaExecs = JavaFinder.searchRegistry("SOFTWARE\\JavaSoft\\Java Development Kit",     WinRegistry.KEY_WOW64_64KEY, javaExecs);

        javaExecs.add(System.getenv("WINDIR") + "\\system32\\java.exe");
        javaExecs.add(System.getenv("WINDIR") + "\\SysWOW64\\java.exe");

        List<JavaInfo> result = new ArrayList<JavaInfo>();
        for (String javaPath: javaExecs) {
            if (!(new File(javaPath).exists())) continue;
            result.add(new JavaInfo(javaPath));
        }
        return result;
    }

    /**
     * @return: The path to a java.exe that has the same bitness as the OS
     * (or null if no matching java is found)
     ****************************************************************************/
    public static String getOSBitnessJava() {
        String arch      = System.getenv("PROCESSOR_ARCHITECTURE");
        String wow64Arch = System.getenv("PROCESSOR_ARCHITEW6432");
        boolean isOS64 = arch.endsWith("64") || (wow64Arch != null && wow64Arch.endsWith("64"));

        List<JavaInfo> javas = JavaFinder.findJavas();
        for (int i = 0; i < javas.size(); i++) {
            if (javas.get(i).is64bits == isOS64) return javas.get(i).path;
        }
        return null;
    }

    /**
     * Standalone testing - lists all Javas in the system
     ****************************************************************************/
    public static void main(String [] args) {
        List<JavaInfo> javas = JavaFinder.findJavas();
        for (int i = 0; i < javas.size(); i++) {
            System.out.println("\n" + javas.get(i));
        }
    }
}

您还需要更新的 WinRegistry.java 来从 Windows 注册表的 32 位和 64 位部分读取值：https://stackoverflow.com/a/11854901/828681

我通常不是java程序员，所以我的代码可能不会遵循java约定。告我吧

以下是我的 Win 7 64 位机器上 JavaFinder.findJavas() 的结果：

>java JavaFinder

C:\Program Files (x86)\Java\jre6\bin\java.exe:
  Version: 1.6.0_31
  Bitness: 32-bits

C:\Program Files\Java\jre6\bin\java.exe:
  Version: 1.6.0_31
  Bitness: 64-bits

D:\Dev\Java\jdk1.6.0_31\bin\java.exe:
  Version: 1.6.0_31
  Bitness: 64-bits

C:\Windows\system32\java.exe:
  Version: 1.6.0_31
  Bitness: 64-bits

C:\Windows\SysWOW64\java.exe:
  Version: 1.6.0_31
  Bitness: 32-bits

注意，SysWOW64 下有一个 32 位 java.exe - 当在 Chrome 或 Firefox 中运行时，它会被 Web Starter 调用，因为它们是 32 位位应用程序 - 除非您使用 JavaFinder 找到正确位的 java.exe 并使用它的完整路径。