spring boot学习(4): 命令行启动

在使用spring boot 构建应用启动时，我们在工作中都是通过命令行来启动应用，有时候会需要一些特定的参数以在应用启动时，做一些初始化的操作。spring boot 提供了 CommandLineRunner 和 ApplicationRunner 这两个接口供用户使用。1. CommandLineRunner1.1 声明:@FunctionalInterfacepublic interface CommandLineRunner { /** * Callback used to run the bean. * @param args incoming main method arguments * @throws Exception on error / void run(String… args) throws Exception;}1.2 使用:package com.example.consoleapplication;import org.springframework.boot.CommandLineRunner;import org.springframework.stereotype.Component;@Componentpublic class TestRunner implements CommandLineRunner { @Override public void run(String… args) { // Do something… for(String arg: args){ System.out.println(arg); } System.out.print(“test command runner”); }}1.3 运行结果运行： java -jar build/libs/consoleapplication-0.0.1-SNAPSHOT.jar -sdfsaf sdfas,结果如下：2019-03-16 17:31:56.544 INFO 18679 — [ main] c.e.consoleapplication.DemoApplication : No active profile set, falling back to default profiles: default2019-03-16 17:31:57.195 INFO 18679 — [ main] c.e.consoleapplication.DemoApplication : Started DemoApplication in 16.172 seconds (JVM running for 16.65)-sdfsafsdfastest command runner%2. ApplicationRunner2.1 声明/* * Interface used to indicate that a bean should <em>run</em> when it is contained within * a {@link SpringApplication}. Multiple {@link ApplicationRunner} beans can be defined * within the same application context and can be ordered using the {@link Ordered} * interface or {@link Order @Order} annotation. * * @author Phillip Webb * @since 1.3.0 * @see CommandLineRunner /@FunctionalInterfacepublic interface ApplicationRunner { /* * Callback used to run the bean. * @param args incoming application arguments * @throws Exception on error */ void run(ApplicationArguments args) throws Exception;}2.2 使用ApplicationRunner 和 CommandLineRunner 的使用是有差别的：CommandLineRunner 的使用，只是把参数根据空格分割。ApplicationRunner 会根据 是否匹配 –key=value 来解析参数，能匹配，则为 optional 参数， 可用getOptionValues获取参数值。不匹配则是 non optional 参数。package com.example.consoleapplication;import org.springframework.boot.ApplicationRunner;import org.springframework.stereotype.Component;import org.springframework.boot.ApplicationArguments;@Componentpublic class TestApplicationRunner implements ApplicationRunner { @Override public void run(ApplicationArguments args) throws Exception { // Do something… System.out.println(“option arg names” + args.getOptionNames()); System.out.println(“non option+” + args.getNonOptionArgs()); }}2.3 运行结果运行命令 java -jar build/libs/consoleapplication-0.0.1-SNAPSHOT.jar -non1 non2 –option=1， 结果为:2019-03-16 18:08:08.528 INFO 19778 — [ main] c.e.consoleapplication.DemoApplication : No active profile set, falling back to default profiles: default2019-03-16 18:08:09.166 INFO 19778 — [ main] c.e.consoleapplication.DemoApplication : Started DemoApplication in 16.059 seconds (JVM running for 16.56)testoption arg names[option]non option+[-non1, non2]-non1non2–option=1test%可以看到， optional 参数名有 option, non optional 参数有 -non1 和 non23. 小结CommandLineRunner 和 ApplicationRunner 都能实现命令行应用启动时根据参数获取我们需要的值，做特殊的逻辑。但两者有所不同，推荐使用 ApplicationRunner 的 optional 参数, 方便扩展。4. 参考文档https://docs.spring.io/spring…