privatestatic String checkHadoopHome() {// first check the Dflag hadoop.home.dir with JVM scopeString home = System.getProperty("hadoop.home.dir");// fall back to the system/user-global env variableif (home == null) {home = System.getenv("HADOOP_HOME");}try {// couldn't find either setting for hadoop's home directoryif (home == null) {thrownew IOException("HADOOP_HOME or hadoop.home.dir are not set.");}if (home.startsWith("\"") && home.endsWith("\"")) {home = home.substring(1, home.length()-1);}// check that the home setting is actually a directory that existsFile homedir = new File(home);if (!homedir.isAbsolute() || !homedir.exists() || !homedir.isDirectory()) {thrownew IOException("Hadoop home directory " + homedir+ " does not exist, is not a directory, or is not an absolute path.");}home = homedir.getCanonicalPath();} catch (IOException ioe) {if (LOG.isDebugEnabled()) {LOG.debug("Failed to detect a valid hadoop home directory", ioe);}home = null;}    return home;}

　　private?static?String?HADOOP_HOME_DIR?=?checkHadoopHome();

publicstaticfinal String getQualifiedBinPath(String executable) throws IOException {// construct hadoop bin path to the specified executableString fullExeName = HADOOP_HOME_DIR + File.separator + "bin" + File.separator + executable;File exeFile = new File(fullExeName);if (!exeFile.exists()) {thrownew IOException("Could not locate executable " + fullExeName+ " in the Hadoop binaries.");}return exeFile.getCanonicalPath();}/** a Windows utility to emulate Unix commands */publicstaticfinal String WINUTILS = getWinUtilsPath();publicstaticfinal String getWinUtilsPath() {String winUtilsPath = null;try {if (WINDOWS) {winUtilsPath = getQualifiedBinPath("winutils.exe");}} catch (IOException ioe) {LOG.error("Failed to locate the winutils binary in the hadoop binary path",ioe);}return winUtilsPath;}