在shell工具中，有专门的getopt函数，使用方法如下所示：
while getopts "d:t:vh" opt; do
case "${opt}" in
"d")
DATE="${OPTARG}"
;;
"t")
ID="${OPTARG}"
ID2=`echo $ID | awk -F "_" '{print $2}'`
;;
"v")
printVersionInfo
exit 0
;;
"h")
printHelpInfo
exit 0
;;
esac
done
其中的”d:t:vh”就是可以接收的选项类型，其中-d和-t意味着可以其后面可以接收参数，而-v和-h后面因为没有：，表示不可以接收参数，只用于单独使用。于是使用这个shell脚本的方式就大概如下：
./example.sh –d “d的参数” –t “t的参数”
./example.sh –h
./example.sh –v
GetOpt在Java1.8的全称为：
com.sun.org.apache.xalan.internal.xsltc.cmdline.getopt.GetOpt
Java程序员不能调用sun.*的相关包，以下是oracle给出的原因：
http://www.oracle.com/technetwork/java/faq-sun-packages-142232.html
既然不能够直接调用，就拷贝过来，反正依赖也不多。
只需要少许改动，解除与ErrorMsg类的依赖，删除一个MissingOptException（同样改成IllegalArgumentException），就可以直接使用了，以下就是修改后的代码：
/*
* Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
/*
* Copyright 2001-2004 The Apache Software Foundation.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* $Id: GetOpt.java,v 1.2.4.1 2005/08/31 11:46:04 pvedula Exp $
*/
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
/**
* GetOpt is a Java equivalent to the C getopt() library function
* discussed in man page getopt(3C). It provides command line
* parsing for Java applications. It supports the most rules of the
* command line standard (see man page intro(1)) including stacked
* options such as '-sxm' (which is equivalent to -s -x -m); it
* handles special '--' option that signifies the end of options.
* Additionally this implementation of getopt will check for
* mandatory arguments to options such as in the case of
* '-d ' it will throw a MissingOptArgException if the
* option argument '' is not included on the commandline.
* getopt(3C) does not check for this.
*
* @author G Todd Miller
*/
public class GetOpt {
public static final String ILLEGAL_CMDLINE_OPTION_ERR = "ILLEGAL_CMDLINE_OPTION_ERR";
public GetOpt(String[] args, String optString) {
theOptions = new ArrayList();
int currOptIndex = 0;
theCmdArgs = new ArrayList();
theOptionMatcher = new OptionMatcher(optString);
// fill in the options list
for (int i = 0; i < args.length; i++) {
String token = args[i];
int tokenLength = token.length();
if (token.equals("--")) { // end of opts
currOptIndex = i + 1; // set index of first operand
break; // end of options
} else if (token.startsWith("-") && tokenLength == 2) {
// simple option token such as '-s' found
theOptions.add(new Option(token.charAt(1)));
} else if (token.startsWith("-") && tokenLength > 2) {
// stacked options found, such as '-shm'
// iterate thru the tokens after the dash and
// add them to theOptions list
for (int j = 1; j < tokenLength; j++) {
theOptions.add(new Option(token.charAt(j)));
}
} else if (!token.startsWith("-")) {
// case 1- there are not options stored yet therefore
// this must be an command argument, not an option argument
if (theOptions.size() == 0) {
currOptIndex = i;
break; // stop processing options
} else {
// case 2-
// there are options stored, check to see if
// this arg belong to the last arg stored
int indexoflast = 0;
indexoflast = theOptions.size() - 1;
Option op = (Option) theOptions.get(indexoflast);
char opLetter = op.getArgLetter();
if (!op.hasArg() && theOptionMatcher.hasArg(opLetter)) {
op.setArg(token);
} else {
// case 3 -
// the last option stored does not take
// an argument, so again, this argument
// must be a command argument, not
// an option argument
currOptIndex = i;
break; // end of options
}
}
}// end option does not start with "-"
} // end for args loop
// attach an iterator to list of options
theOptionsIterator = theOptions.listIterator();
// options are done, now fill out cmd arg list with remaining args
for (int i = currOptIndex; i < args.length; i++) {
String token = args[i];
theCmdArgs.add(token);
}
}
/**
* debugging routine to print out all options collected
*/
public void printOptions() {
for (ListIterator it = theOptions.listIterator(); it.hasNext(); ) {
Option opt = (Option) it.next();
System.out.print("OPT =" + opt.getArgLetter());
String arg = opt.getArgument();
if (arg != null) {
System.out.print(" " + arg);
}
System.out.println();
}
}
/**
* gets the next option found in the commandline. Distinguishes
* between two bad cases, one case is when an illegal option
* is found, and then other case is when an option takes an
* argument but no argument was found for that option.
* If the option found was not declared in the optString, then
* an IllegalArgumentException will be thrown (case 1).
* If the next option found has been declared to take an argument,
* and no such argument exists, then a MissingOptArgException
* is thrown (case 2).
*
* @return int - the next option found.
* @throws IllegalArgumentException, MissingOptArgException.
*/
public int getNextOption() throws IllegalArgumentException {
int retval = -1;
if (theOptionsIterator.hasNext()) {
theCurrentOption = (Option) theOptionsIterator.next();
char c = theCurrentOption.getArgLetter();
boolean shouldHaveArg = theOptionMatcher.hasArg(c);
String arg = theCurrentOption.getArgument();
if (!theOptionMatcher.match(c)) {
// ErrorMsg msg = new ErrorMsg(ErrorMsg.ILLEGAL_CMDLINE_OPTION_ERR,
// new Character(c));
throw (new IllegalArgumentException(String.format("%s : %s", ILLEGAL_CMDLINE_OPTION_ERR, new Character(c))));
} else if (shouldHaveArg && (arg == null)) {
throw (new IllegalArgumentException(String.format("%s : %s", ILLEGAL_CMDLINE_OPTION_ERR, new Character(c))));
}
retval = c;
}
return retval;
}
/**
* gets the argument for the current parsed option. For example,
* in case of '-d ', if current option parsed is 'd' then
* getOptionArg() would return ''.
*
* @return String - argument for current parsed option.
*/
public String getOptionArg() {
String retval = null;
String tmp = theCurrentOption.getArgument();
char c = theCurrentOption.getArgLetter();
if (theOptionMatcher.hasArg(c)) {
retval = tmp;
}
return retval;
}
/**
* gets list of the commandline arguments. For example, in command
* such as 'cmd -s -d file file2 file3 file4' with the usage
* 'cmd [-s] [-d ] ...', getCmdArgs() would return
* the list {file2, file3, file4}.
*
* @return String[] - list of command arguments that may appear
* after options and option arguments.
* @params none
*/
public String[] getCmdArgs() {
String[] retval = new String[theCmdArgs.size()];
int i = 0;
for (ListIterator it = theCmdArgs.listIterator(); it.hasNext(); ) {
retval[i++] = (String) it.next();
}
return retval;
}
private Option theCurrentOption = null;
private ListIterator theOptionsIterator;
private List theOptions = null;
private List theCmdArgs = null;
private OptionMatcher theOptionMatcher = null;
///
//
// Inner Classes
//
///
// inner class to model an option
class Option {
private char theArgLetter;
private String theArgument = null;
public Option(char argLetter) {
theArgLetter = argLetter;
}
public void setArg(String arg) {
theArgument = arg;
}
public boolean hasArg() {
return (theArgument != null);
}
public char getArgLetter() {
return theArgLetter;
}
public String getArgument() {
return theArgument;
}
} // end class Option
// inner class to query optString for a possible option match,
// and whether or not a given legal option takes an argument.
//
class OptionMatcher {
public OptionMatcher(String optString) {
theOptString = optString;
}
public boolean match(char c) {
boolean retval = false;
if (theOptString.indexOf(c) != -1) {
retval = true;
}
return retval;
}
public boolean hasArg(char c) {
boolean retval = false;
int index = theOptString.indexOf(c) + 1;
if (index == theOptString.length()) {
// reached end of theOptString
retval = false;
} else if (theOptString.charAt(index) == ':') {
retval = true;
}
return retval;
}
private String theOptString = null;
} // end class OptionMatcher
}// end class GetOpt
我们先看GetOpt的构造函数，接收两个参数，第一个就是通过public static void main(String[] args)来指定的，也就是传过来的参数；第二个参数就更加重要了，这个是用来设置可接受选项类型的，这也是与shell中的getopt函数有着相同的含义。
下面就是一段关于getOpt函数的简单使用说明，对于每个选项，不用考虑其出现的顺序，这里也同样接收四种类型选项，其中d,t带具体的附加参数，而v,h没有附加参数，只作为帮助以及版本信息显示使用。
GetOpt getOpt = new GetOpt(args, "d:t:vh");
while ((c = getOpt.getNextOption()) != -1) {
System.out.println((char)c);
switch (c) {
case 'd':
dateString = getOpt.getOptionArg();
break;
case 't':
campaignId = getOpt.getOptionArg();
break;
case 'h' :
printHelpInfo();
break;
case 'v':
printVersionInfo();
break;
}
}
使用getNextOption()函数来逐个获取下一个选项，直到返回-1表示没有下一个参数可以处理。通过switch/case语句对每个选项的附加参数进行区分，并结合getOptionArg()返回该选项中的附件参数，并进行处理。
如果输入了不合法的参数字符，就会抛出以下的错误信息（表明a是未定义的参数字符）：
java.lang.IllegalArgumentException: ILLEGAL_CMDLINE_OPTION_ERR : a
at.utils.GetOpt.getNextOption(GetOpt.java:151)
以上就是java中使用getOpt函数的总体介绍，这对于处理linux形式的参数有着非常好的支持，并且符合程序员的习惯。