SPRINGBOOT啟動命令參數(shù)及源碼詳析

java -jar xxx.jar abc def 

java -jar -Dserver.port=8081 xxx.jar

@RestController
public class ArgumentsController {
  @Resource
  private ApplicationArguments arguments;
}

@RestController
public class ParamController {
  @Value("${server.port}")
  private String serverPort;
}

String systemServerPort = System.getProperty("server.port");

java -jar --server.port=8081 xxx.jar

@RestController
public class ArgumentsController {
  @Resource
  private ApplicationArguments arguments;
  @GetMapping("/args")
  public String getArgs() {
    System.out.println("# 非選項參數(shù)數(shù)量: " + arguments.getNonOptionArgs().size());
    System.out.println("# 選項參數(shù)數(shù)量: " + arguments.getOptionNames().size());
    System.out.println("# 非選項具體參數(shù):");
    arguments.getNonOptionArgs().forEach(System.out::println);
    System.out.println("# 選項參數(shù)具體參數(shù):");
    arguments.getOptionNames().forEach(optionName -> {
      System.out.println("--" + optionName + "=" + arguments.getOptionValues(optionName));
    });
    return "success";
  }
}

public interface ApplicationArguments {
  /**
   * 原始參數(shù)數(shù)組（未經(jīng)過處理的參數(shù)）
   */
  String[] getSourceArgs();
  /**
   * 選項參數(shù)名稱
   */
  Set<String> getOptionNames();
  /**
   * 根據(jù)名稱校驗是否包含選項參數(shù)
   */
  boolean containsOption(String name);
  /**
   * 根據(jù)名稱獲得選項參數(shù)
   */
  List<String> getOptionValues(String name);
  /**
   * 獲取非選項參數(shù)列表
   */
  List<String> getNonOptionArgs();
}

public ConfigurableApplicationContext run(String... args) {
  try {
    ApplicationArguments applicationArguments = new DefaultApplicationArguments(args);
    // ...
    prepareContext(context, environment, listeners, // ...
  } catch (Throwable ex) {
    // ...
  }
  return context;
}

public class DefaultApplicationArguments implements ApplicationArguments {
  private final Source source;
  private final String[] args;
  public DefaultApplicationArguments(String... args) {
    Assert.notNull(args, "Args must not be null");
    this.source = new Source(args);
    this.args = args;
  }
  // ...
  @Override
  public List<String> getOptionValues(String name) {
    List<String> values = this.source.getOptionValues(name);
    return (values != null) ? Collections.unmodifiableList(values) : null;
  }
  private static class Source extends SimpleCommandLinePropertySource {
    Source(String[] args) {
      super(args);
    }
    // ...
  }
}

public SimpleCommandLinePropertySource(String... args) {
  super(new SimpleCommandLineArgsParser().parse(args));
}

class SimpleCommandLineArgsParser {
  public CommandLineArgs parse(String... args) {
    CommandLineArgs commandLineArgs = new CommandLineArgs();
    for (String arg : args) {
      // --開頭的選參數(shù)解析
      if (arg.startsWith("--")) {
        // 獲得key=value或key值
        String optionText = arg.substring(2, arg.length());
        String optionName;
        String optionValue = null;
        // 如果是key=value格式則進(jìn)行解析
        if (optionText.contains("=")) {
          optionName = optionText.substring(0, optionText.indexOf('='));
          optionValue = optionText.substring(optionText.indexOf('=')+1, optionText.length());
        } else {
          // 如果是僅有key（--foo）則獲取其值
          optionName = optionText;
        }
        // 如果optionName為空或者optionValue不為空但optionName為空則拋出異常
        if (optionName.isEmpty() || (optionValue != null && optionValue.isEmpty())) {
          throw new IllegalArgumentException("Invalid argument syntax: " + arg);
        }
        // 封裝入CommandLineArgs
        commandLineArgs.addOptionArg(optionName, optionValue);
      } else {
        commandLineArgs.addNonOptionArg(arg);
      }
    }
    return commandLineArgs;
  }
}

private void prepareContext(ConfigurableApplicationContext context, ConfigurableEnvironment environment,
    SpringApplicationRunListeners listeners, ApplicationArguments applicationArguments, Banner printedBanner) {
  // ...
  ConfigurableListableBeanFactory beanFactory = context.getBeanFactory();
  // 通過beanFactory將ApplicationArguments的對象注入Spring容器
  beanFactory.registerSingleton("springApplicationArguments", applicationArguments);
  // ...
}