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. commandlinerunner
1.1 声明:
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@functionalinterface public 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:
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package com.example.consoleapplication; import org.springframework.boot.commandlinerunner; import org.springframework.stereotype.component; @component public 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: default
2019-03-16 17:31:57.195 info 18679 --- [ main] c.e.consoleapplication.demoapplication : started demoapplication in 16.172 seconds (jvm running for 16.65)
-sdfsaf
sdfas
test command runner%
2. applicationrunner
2.1 声明
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/** * 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 */ @functionalinterface public 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。
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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。
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package com.example.consoleapplication; import org.springframework.boot.applicationrunner; import org.springframework.stereotype.component; import org.springframework.boot.applicationarguments; @component public 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: default
2019-03-16 18:08:09.166 info 19778 --- [ main] c.e.consoleapplication.demoapplication : started demoapplication in 16.059 seconds (jvm running for 16.56)
test
option arg names[option]
non option+[-non1, non2]-non1
non2
--option=1
test%
可以看到, optional 参数名有 option, non optional 参数有 -non1 和 non2
3. 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
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持服务器之家。
原文链接:https://segmentfault.com/a/1190000018530137