springboot-热部署

什么是热部署

事先我创建一个springboot项目，引入web依赖。

当我冷启动的时候，日志如下：

D:\tools\jdk-17.0.3\bin\java.exe -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dspring.jmx.enabled=true -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true -javaagent:D:\tools\IDEA\lib\idea_rt.jar=6005:D:\tools\IDEA\bin -Dfile.encoding=UTF-8 -classpath E:\java\springboot\project_course\hot-start\target\classes;D:\repository\org\springframework\boot\spring-boot-devtools\3.0.2\spring-boot-devtools-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot\3.0.2\spring-boot-3.0.2.jar;D:\repository\org\springframework\spring-context\6.0.4\spring-context-6.0.4.jar;D:\repository\org\springframework\boot\spring-boot-autoconfigure\3.0.2\spring-boot-autoconfigure-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot-starter-web\3.0.2\spring-boot-starter-web-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot-starter\3.0.2\spring-boot-starter-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot-starter-logging\3.0.2\spring-boot-starter-logging-3.0.2.jar;D:\repository\ch\qos\logback\logback-classic\1.4.5\logback-classic-1.4.5.jar;D:\repository\ch\qos\logback\logback-core\1.4.5\logback-core-1.4.5.jar;D:\repository\org\apache\logging\log4j\log4j-to-slf4j\2.19.0\log4j-to-slf4j-2.19.0.jar;D:\repository\org\apache\logging\log4j\log4j-api\2.19.0\log4j-api-2.19.0.jar;D:\repository\org\slf4j\jul-to-slf4j\2.0.6\jul-to-slf4j-2.0.6.jar;D:\repository\jakarta\annotation\jakarta.annotation-api\2.1.1\jakarta.annotation-api-2.1.1.jar;D:\repository\org\yaml\snakeyaml\1.33\snakeyaml-1.33.jar;D:\repository\org\springframework\boot\spring-boot-starter-json\3.0.2\spring-boot-starter-json-3.0.2.jar;D:\repository\com\fasterxml\jackson\core\jackson-databind\2.14.1\jackson-databind-2.14.1.jar;D:\repository\com\fasterxml\jackson\core\jackson-annotations\2.14.1\jackson-annotations-2.14.1.jar;D:\repository\com\fasterxml\jackson\core\jackson-core\2.14.1\jackson-core-2.14.1.jar;D:\repository\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.14.1\jackson-datatype-jdk8-2.14.1.jar;D:\repository\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.14.1\jackson-datatype-jsr310-2.14.1.jar;D:\repository\com\fasterxml\jackson\module\jackson-module-parameter-names\2.14.1\jackson-module-parameter-names-2.14.1.jar;D:\repository\org\springframework\boot\spring-boot-starter-tomcat\3.0.2\spring-boot-starter-tomcat-3.0.2.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-core\10.1.5\tomcat-embed-core-10.1.5.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-el\10.1.5\tomcat-embed-el-10.1.5.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-websocket\10.1.5\tomcat-embed-websocket-10.1.5.jar;D:\repository\org\springframework\spring-web\6.0.4\spring-web-6.0.4.jar;D:\repository\org\springframework\spring-beans\6.0.4\spring-beans-6.0.4.jar;D:\repository\io\micrometer\micrometer-observation\1.10.3\micrometer-observation-1.10.3.jar;D:\repository\io\micrometer\micrometer-commons\1.10.3\micrometer-commons-1.10.3.jar;D:\repository\org\springframework\spring-webmvc\6.0.4\spring-webmvc-6.0.4.jar;D:\repository\org\springframework\spring-aop\6.0.4\spring-aop-6.0.4.jar;D:\repository\org\springframework\spring-expression\6.0.4\spring-expression-6.0.4.jar;D:\repository\org\slf4j\slf4j-api\2.0.6\slf4j-api-2.0.6.jar;D:\repository\org\springframework\spring-core\6.0.4\spring-core-6.0.4.jar;D:\repository\org\springframework\spring-jcl\6.0.4\spring-jcl-6.0.4.jar cn.oesoft.hotstart.HotStartApplication
Java HotSpot(TM) 64-Bit Server VM warning: Options -Xverify:none and -noverify were deprecated in JDK 13 and will likely be removed in a future release.

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.0.2)

2023-05-11T15:40:21.186+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Starting HotStartApplication using Java 17.0.3 with PID 18892 (E:\java\springboot\project_course\hot-start\target\classes started by Administrator in E:\java\springboot\project_course\hot-start)
2023-05-11T15:40:21.186+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : No active profile set, falling back to 1 default profile: "default"
2023-05-11T15:40:21.273+08:00  INFO 18892 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-05-11T15:40:21.273+08:00  INFO 18892 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : An older version [1.2.36] of the Apache Tomcat Native library is installed, while Tomcat recommends a minimum version of [2.0.1]
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : Loaded Apache Tomcat Native library [1.2.36] using APR version [1.7.2].
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1t  7 Feb 2023]
2023-05-11T15:40:22.561+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-05-11T15:40:22.561+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.5]
2023-05-11T15:40:22.639+08:00  INFO 18892 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-05-11T15:40:22.639+08:00  INFO 18892 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1366 ms
2023-05-11T15:40:22.890+08:00  INFO 18892 --- [  restartedMain] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2023-05-11T15:40:23.015+08:00  INFO 18892 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-05-11T15:40:23.078+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-05-11T15:40:23.094+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Started HotStartApplication in 2.455 seconds (process running for 3.9)
ccc

当我修改了两个Java类，一个是启动类，使它输出aaa，不再是ccc，一个是controller类，热部署的日志如下：

D:\tools\jdk-17.0.3\bin\java.exe -XX:TieredStopAtLevel=1 -noverify -Dspring.output.ansi.enabled=always -Dcom.sun.management.jmxremote -Dspring.jmx.enabled=true -Dspring.liveBeansView.mbeanDomain -Dspring.application.admin.enabled=true -javaagent:D:\tools\IDEA\lib\idea_rt.jar=6005:D:\tools\IDEA\bin -Dfile.encoding=UTF-8 -classpath E:\java\springboot\project_course\hot-start\target\classes;D:\repository\org\springframework\boot\spring-boot-devtools\3.0.2\spring-boot-devtools-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot\3.0.2\spring-boot-3.0.2.jar;D:\repository\org\springframework\spring-context\6.0.4\spring-context-6.0.4.jar;D:\repository\org\springframework\boot\spring-boot-autoconfigure\3.0.2\spring-boot-autoconfigure-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot-starter-web\3.0.2\spring-boot-starter-web-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot-starter\3.0.2\spring-boot-starter-3.0.2.jar;D:\repository\org\springframework\boot\spring-boot-starter-logging\3.0.2\spring-boot-starter-logging-3.0.2.jar;D:\repository\ch\qos\logback\logback-classic\1.4.5\logback-classic-1.4.5.jar;D:\repository\ch\qos\logback\logback-core\1.4.5\logback-core-1.4.5.jar;D:\repository\org\apache\logging\log4j\log4j-to-slf4j\2.19.0\log4j-to-slf4j-2.19.0.jar;D:\repository\org\apache\logging\log4j\log4j-api\2.19.0\log4j-api-2.19.0.jar;D:\repository\org\slf4j\jul-to-slf4j\2.0.6\jul-to-slf4j-2.0.6.jar;D:\repository\jakarta\annotation\jakarta.annotation-api\2.1.1\jakarta.annotation-api-2.1.1.jar;D:\repository\org\yaml\snakeyaml\1.33\snakeyaml-1.33.jar;D:\repository\org\springframework\boot\spring-boot-starter-json\3.0.2\spring-boot-starter-json-3.0.2.jar;D:\repository\com\fasterxml\jackson\core\jackson-databind\2.14.1\jackson-databind-2.14.1.jar;D:\repository\com\fasterxml\jackson\core\jackson-annotations\2.14.1\jackson-annotations-2.14.1.jar;D:\repository\com\fasterxml\jackson\core\jackson-core\2.14.1\jackson-core-2.14.1.jar;D:\repository\com\fasterxml\jackson\datatype\jackson-datatype-jdk8\2.14.1\jackson-datatype-jdk8-2.14.1.jar;D:\repository\com\fasterxml\jackson\datatype\jackson-datatype-jsr310\2.14.1\jackson-datatype-jsr310-2.14.1.jar;D:\repository\com\fasterxml\jackson\module\jackson-module-parameter-names\2.14.1\jackson-module-parameter-names-2.14.1.jar;D:\repository\org\springframework\boot\spring-boot-starter-tomcat\3.0.2\spring-boot-starter-tomcat-3.0.2.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-core\10.1.5\tomcat-embed-core-10.1.5.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-el\10.1.5\tomcat-embed-el-10.1.5.jar;D:\repository\org\apache\tomcat\embed\tomcat-embed-websocket\10.1.5\tomcat-embed-websocket-10.1.5.jar;D:\repository\org\springframework\spring-web\6.0.4\spring-web-6.0.4.jar;D:\repository\org\springframework\spring-beans\6.0.4\spring-beans-6.0.4.jar;D:\repository\io\micrometer\micrometer-observation\1.10.3\micrometer-observation-1.10.3.jar;D:\repository\io\micrometer\micrometer-commons\1.10.3\micrometer-commons-1.10.3.jar;D:\repository\org\springframework\spring-webmvc\6.0.4\spring-webmvc-6.0.4.jar;D:\repository\org\springframework\spring-aop\6.0.4\spring-aop-6.0.4.jar;D:\repository\org\springframework\spring-expression\6.0.4\spring-expression-6.0.4.jar;D:\repository\org\slf4j\slf4j-api\2.0.6\slf4j-api-2.0.6.jar;D:\repository\org\springframework\spring-core\6.0.4\spring-core-6.0.4.jar;D:\repository\org\springframework\spring-jcl\6.0.4\spring-jcl-6.0.4.jar cn.oesoft.hotstart.HotStartApplication
Java HotSpot(TM) 64-Bit Server VM warning: Options -Xverify:none and -noverify were deprecated in JDK 13 and will likely be removed in a future release.

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.0.2)

2023-05-11T15:40:21.186+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Starting HotStartApplication using Java 17.0.3 with PID 18892 (E:\java\springboot\project_course\hot-start\target\classes started by Administrator in E:\java\springboot\project_course\hot-start)
2023-05-11T15:40:21.186+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : No active profile set, falling back to 1 default profile: "default"
2023-05-11T15:40:21.273+08:00  INFO 18892 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-05-11T15:40:21.273+08:00  INFO 18892 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : An older version [1.2.36] of the Apache Tomcat Native library is installed, while Tomcat recommends a minimum version of [2.0.1]
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : Loaded Apache Tomcat Native library [1.2.36] using APR version [1.7.2].
2023-05-11T15:40:22.545+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1t  7 Feb 2023]
2023-05-11T15:40:22.561+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-05-11T15:40:22.561+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.5]
2023-05-11T15:40:22.639+08:00  INFO 18892 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-05-11T15:40:22.639+08:00  INFO 18892 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1366 ms
2023-05-11T15:40:22.890+08:00  INFO 18892 --- [  restartedMain] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2023-05-11T15:40:23.015+08:00  INFO 18892 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-05-11T15:40:23.078+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-05-11T15:40:23.094+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Started HotStartApplication in 2.455 seconds (process running for 3.9)
ccc
2023-05-11T15:53:21.057+08:00  INFO 18892 --- [   File Watcher] rtingClassPathChangeChangedEventListener : Restarting due to 2 class path changes (0 additions, 2 deletions, 0 modifications)
2023-05-11T15:53:21.135+08:00  INFO 18892 --- [       Thread-5] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.0.2)

2023-05-11T15:53:21.259+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Starting HotStartApplication using Java 17.0.3 with PID 18892 (E:\java\springboot\project_course\hot-start\target\classes started by Administrator in E:\java\springboot\project_course\hot-start)
2023-05-11T15:53:21.259+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : No active profile set, falling back to 1 default profile: "default"
2023-05-11T15:53:21.615+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-05-11T15:53:21.615+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : An older version [1.2.36] of the Apache Tomcat Native library is installed, while Tomcat recommends a minimum version of [2.0.1]
2023-05-11T15:53:21.615+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : Loaded Apache Tomcat Native library [1.2.36] using APR version [1.7.2].
2023-05-11T15:53:21.615+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1t  7 Feb 2023]
2023-05-11T15:53:21.615+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-05-11T15:53:21.615+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.5]
2023-05-11T15:53:21.633+08:00  INFO 18892 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-05-11T15:53:21.633+08:00  INFO 18892 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 374 ms
2023-05-11T15:53:21.725+08:00  INFO 18892 --- [  restartedMain] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2023-05-11T15:53:21.788+08:00  INFO 18892 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-05-11T15:53:21.804+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-05-11T15:53:21.819+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Started HotStartApplication in 0.612 seconds (process running for 782.628)
2023-05-11T15:53:21.819+08:00  INFO 18892 --- [  restartedMain] .ConditionEvaluationDeltaLoggingListener : Condition evaluation unchanged
ccc
2023-05-11T15:53:24.225+08:00  INFO 18892 --- [   File Watcher] rtingClassPathChangeChangedEventListener : Restarting due to 2 class path changes (2 additions, 0 deletions, 0 modifications)
2023-05-11T15:53:24.272+08:00  INFO 18892 --- [       Thread-7] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::                (v3.0.2)

2023-05-11T15:53:24.366+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Starting HotStartApplication using Java 17.0.3 with PID 18892 (E:\java\springboot\project_course\hot-start\target\classes started by Administrator in E:\java\springboot\project_course\hot-start)
2023-05-11T15:53:24.366+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : No active profile set, falling back to 1 default profile: "default"
2023-05-11T15:53:24.660+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-05-11T15:53:24.660+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : An older version [1.2.36] of the Apache Tomcat Native library is installed, while Tomcat recommends a minimum version of [2.0.1]
2023-05-11T15:53:24.660+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : Loaded Apache Tomcat Native library [1.2.36] using APR version [1.7.2].
2023-05-11T15:53:24.660+08:00  INFO 18892 --- [  restartedMain] o.a.catalina.core.AprLifecycleListener   : OpenSSL successfully initialized [OpenSSL 1.1.1t  7 Feb 2023]
2023-05-11T15:53:24.660+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-05-11T15:53:24.660+08:00  INFO 18892 --- [  restartedMain] o.apache.catalina.core.StandardEngine    : Starting Servlet engine: [Apache Tomcat/10.1.5]
2023-05-11T15:53:24.676+08:00  INFO 18892 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-05-11T15:53:24.676+08:00  INFO 18892 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 294 ms
2023-05-11T15:53:24.740+08:00  INFO 18892 --- [  restartedMain] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2023-05-11T15:53:24.785+08:00  INFO 18892 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-05-11T15:53:24.801+08:00  INFO 18892 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-05-11T15:53:24.801+08:00  INFO 18892 --- [  restartedMain] cn.oesoft.hotstart.HotStartApplication   : Started HotStartApplication in 0.465 seconds (process running for 785.615)
2023-05-11T15:53:24.801+08:00  INFO 18892 --- [  restartedMain] .ConditionEvaluationDeltaLoggingListener : Condition evaluation unchanged
aaa

分析如下：

热部署始终使用同一个进程，冷启动创建一个新的进程。在热部署例子中，修改了两个类，但类路径上是先删除后增加两个字节码文件，导致两次热部署，但明显用时比冷启动要短。在类路径上删除启动类字节码后，热部署时不会删除它，要是删除它，应用就运行不了，但删除controller类字节码后，热部署时spring容器就会删除它，导致某段时间访问时，出现404。

结论：

热部署就是重启：自定义开发代码，包括类、页面、配置文件等，加载位置是restart类加载器,如下：

18:22:39.453 [Thread-0] DEBUG org.springframework.boot.devtools.restart.classloader.RestartClassLoader - Created RestartClassLoader org.springframework.boot.devtools.restart.classloader.RestartClassLoader@316ec5b4

 冷启动的话还包括重载：jar包，加载位置是base类加载器。 

如何实现热部署

springboot使用内嵌的Tomcat，Tomcat也是spring容器的一个对象，那么这个对象如何知道自定义代码发生了变化？需要有个工具帮助它，如下：

在pom文件中添加spring-boot-devtools热部署依赖

    org.springframework.boot
    spring-boot-devtools

手动热部署：

build-》build project，激活热部署

自动热部署：

设置自动构建

eclipse：

idea：

IDEA配置热部署_idea热部署配置_微风粼粼的博客-CSDN博客

1、file-》settings-》build..-》compiler->build project automatically

2、ctrl+Alt+shift+/ ->registry...->选中compiler.automake.allow.when.app.running(如果存在)  

激活方式：焦点离开idea 5秒后 重启

热部署测试

修改HelloController的方法的返回值

热部署配置范围

默认不触发重启的目录列表

/META-INF/maven

/META-INF/resources

/resources

/static

/public

/templates

设置不触发重启的项

spring.devtools.restart.exclude=config/application.properties,static/**

禁用热部署

spring.devtools.restart.enabled=false

由于其他人也会通过配置启用热部署，导致自己的配置失效，那么我们可以在更高一层配置。

先看下属性加载优先顺序（由低到高）

参看 https://docs.spring.io/spring-boot/docs/current/reference/html/spring-boot-features.html#boot-features-external-config

 我们可以通过第六级完成更高一层的配置

@SpringBootApplication
public class HotStartApplication {

    public static void main(String[] args) {
        System.setProperty("spring.devtools.restart.enabled","false");
        SpringApplication.run(HotStartApplication.class, args);
    }

}