在Java中解析命令行参数的好方法是什么?
当前回答
看看Commons CLI项目,里面有很多好东西。
其他回答
这是谷歌的命令行解析库,作为Bazel项目的一部分是开源的。我个人认为它是最好的,比Apache CLI简单得多。
https://github.com/pcj/google-options
安装
Bazel
maven_jar(
name = "com_github_pcj_google_options",
artifact = "com.github.pcj:google-options:jar:1.0.0",
sha1 = "85d54fe6771e5ff0d54827b0a3315c3e12fdd0c7",
)
Gradle
dependencies {
compile 'com.github.pcj:google-options:1.0.0'
}
Maven
<dependency>
<groupId>com.github.pcj</groupId>
<artifactId>google-options</artifactId>
<version>1.0.0</version>
</dependency>
使用
创建一个扩展OptionsBase并定义@Option(s)的类。
package example;
import com.google.devtools.common.options.Option;
import com.google.devtools.common.options.OptionsBase;
import java.util.List;
/**
* Command-line options definition for example server.
*/
public class ServerOptions extends OptionsBase {
@Option(
name = "help",
abbrev = 'h',
help = "Prints usage info.",
defaultValue = "true"
)
public boolean help;
@Option(
name = "host",
abbrev = 'o',
help = "The server host.",
category = "startup",
defaultValue = ""
)
public String host;
@Option(
name = "port",
abbrev = 'p',
help = "The server port.",
category = "startup",
defaultValue = "8080"
)
public int port;
@Option(
name = "dir",
abbrev = 'd',
help = "Name of directory to serve static files.",
category = "startup",
allowMultiple = true,
defaultValue = ""
)
public List<String> dirs;
}
解析参数并使用它们。
package example;
import com.google.devtools.common.options.OptionsParser;
import java.util.Collections;
public class Server {
public static void main(String[] args) {
OptionsParser parser = OptionsParser.newOptionsParser(ServerOptions.class);
parser.parseAndExitUponError(args);
ServerOptions options = parser.getOptions(ServerOptions.class);
if (options.host.isEmpty() || options.port < 0 || options.dirs.isEmpty()) {
printUsage(parser);
return;
}
System.out.format("Starting server at %s:%d...\n", options.host, options.port);
for (String dirname : options.dirs) {
System.out.format("\\--> Serving static files at <%s>\n", dirname);
}
}
private static void printUsage(OptionsParser parser) {
System.out.println("Usage: java -jar server.jar OPTIONS");
System.out.println(parser.describeOptions(Collections.<String, String>emptyMap(),
OptionsParser.HelpVerbosity.LONG));
}
}
https://github.com/pcj/google-options
我使用过JOpt,发现它非常方便:http://jopt-simple.sourceforge.net/
首页还提供了一个大约8个备选库的列表,检查它们并选择最适合您的需求。
看看这些:
http://commons.apache.org/cli/ http://www.martiansoftware.com/jsap/
或者自己卷:
http://docs.oracle.com/javase/7/docs/api/java/util/Scanner.html
例如,这是你如何使用common -cli来解析2个字符串参数:
import org.apache.commons.cli.*;
public class Main {
public static void main(String[] args) throws Exception {
Options options = new Options();
Option input = new Option("i", "input", true, "input file path");
input.setRequired(true);
options.addOption(input);
Option output = new Option("o", "output", true, "output file");
output.setRequired(true);
options.addOption(output);
CommandLineParser parser = new DefaultParser();
HelpFormatter formatter = new HelpFormatter();
CommandLine cmd = null;//not a good practice, it serves it purpose
try {
cmd = parser.parse(options, args);
} catch (ParseException e) {
System.out.println(e.getMessage());
formatter.printHelp("utility-name", options);
System.exit(1);
}
String inputFilePath = cmd.getOptionValue("input");
String outputFilePath = cmd.getOptionValue("output");
System.out.println(inputFilePath);
System.out.println(outputFilePath);
}
}
命令行用法:
$> java -jar target/my-utility.jar -i asd
Missing required option: o
usage: utility-name
-i,--input <arg> input file path
-o,--output <arg> output file
看看Commons CLI项目,里面有很多好东西。
For Spring users, we should mention also https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/core/env/SimpleCommandLinePropertySource.html and his twin brother https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/core/env/JOptCommandLinePropertySource.html (JOpt implementation of the same functionality). The advantage in Spring is that you can directly bind the command line arguments to attributes, there is an example here https://docs.spring.io/spring/docs/current/javadoc-api/org/springframework/core/env/CommandLinePropertySource.html
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