Java

Springboot 启动时自动运行某个方法

admin 1153 次阅读 约 2 分钟
java SpringBoot

引言

在项目开发的过程中，有时候需要在项目启动时执行特定方法，比如初始化临时数据库，提前把数据放到缓存里，检查运行环境等等。

👀 运行参数 -a -b -c --name=zunmx

解决方案

静态方法

ℹ：不足之处是不能通过容器进行注入其它方法，可用性比较低，应用有场景，但是并不多。

@Component()
public class AutoRun {
    @Autowired
    private InsideDBO insideDBO;

    static {
        System.out.println("自动运行方法：静态方法");
        System.out.println("    不能通过容器注入方法。"); // 这里是不能使用insideDBO的
    }
}

通过PostConstruct注解

@Component
public class AutoRun2 {

    @Autowired
    private InsideDBO insideDBO;

    @PostConstruct
    public void run() {
        System.out.println("自动运行方法：PostConstruct");
        insideDBO.hello();
    }
}

通过实现ServletContextAware接口

ℹ：这个只限于servlet工程。web应用被加载之后，服务器会创建出代表整个web应用的ServletContext对象，跟随于servlet的生命周期。

@Component
public class AutoRun3 implements ServletContextAware {
    @Autowired
    private InsideDBO insideDBO;

    public AutoRun3(){
        System.out.println("A3类被实例化了");
    }
    @Override
    public void setServletContext(ServletContext servletContext) {
        System.out.println("自动运行方法：实现ServletContextAware接口");
        insideDBO.hello();
    }
}

实现ApplicationRunner接口

ℹ：此方法在Springboot启动完成后指定的调用

@Component
public class AutoRun4 implements ApplicationRunner {
    @Override
    public void run(ApplicationArguments args) throws Exception {
        System.out.println("启动时自动执行 ApplicationRunner 的 run 方法");

        Set<String> optionNames = args.getOptionNames();
        for (String optionName : optionNames) {
            System.out.printf("这是传过来的参数[%s],参数值为%s \n", optionName, args.getOptionValues(optionName));
        }
        String[] sourceArgs = args.getSourceArgs();
        for (String sourceArg : sourceArgs) {
            System.out.printf("这是传过来sourceArgs[%s] \n", sourceArg);
        }
    }
}

执行顺序

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::               (v2.7.14)

2023-08-04 10:47:11.125  INFO 5044 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : Starting DbManagerApplication using Java 1.8.0_151 on ZUNMX with PID 5044 (E:\StudyCode\Java\DBManager\target\classes started by 36083 in E:\StudyCode\Java\DBManager)
2023-08-04 10:47:11.125  INFO 5044 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : No active profile set, falling back to 1 default profile: "default"
2023-08-04 10:47:11.151  INFO 5044 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-08-04 10:47:11.151  INFO 5044 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-08-04 10:47:11.629  INFO 5044 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-08-04 10:47:11.633  INFO 5044 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-08-04 10:47:11.633  INFO 5044 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.78]
2023-08-04 10:47:11.670  INFO 5044 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-08-04 10:47:11.670  INFO 5044 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 519 ms
自动运行方法：静态方法
    不能通过容器注入方法。
A1类被实例化了
A2类被实例化了
自动运行方法：PostConstruct
    这是组件中的方法：hello
A3类被实例化了
自动运行方法：实现ServletContextAware接口
    这是组件中的方法：hello
2023-08-04 10:47:11.830  INFO 5044 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-08-04 10:47:11.847  INFO 5044 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-08-04 10:47:11.853  INFO 5044 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : Started DbManagerApplication in 0.907 seconds (JVM running for 1.587)
启动时自动执行 ApplicationRunner 的 run 方法
    这是组件中的方法：hello
这是传过来的参数[name],参数值为[zunmx] 
这是传过来sourceArgs[-a] 
这是传过来sourceArgs[-b] 
这是传过来sourceArgs[-c] 
这是传过来sourceArgs[--name=zunmx]

如果改变了方法的名称，也就是说，springboot在组件扫描的时候，也是根据类名进行排序，名字在前的先被托管，名字在后的后被托管，结果如下所示

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::               (v2.7.14)

2023-08-04 10:48:19.079  INFO 21316 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : Starting DbManagerApplication using Java 1.8.0_151 on ZUNMX with PID 21316 (E:\StudyCode\Java\DBManager\target\classes started by 36083 in E:\StudyCode\Java\DBManager)
2023-08-04 10:48:19.080  INFO 21316 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : No active profile set, falling back to 1 default profile: "default"
2023-08-04 10:48:19.107  INFO 21316 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-08-04 10:48:19.107  INFO 21316 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-08-04 10:48:19.670  INFO 21316 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-08-04 10:48:19.675  INFO 21316 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-08-04 10:48:19.675  INFO 21316 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.78]
2023-08-04 10:48:19.716  INFO 21316 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-08-04 10:48:19.716  INFO 21316 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 609 ms
A3类被实例化了
自动运行方法：实现ServletContextAware接口
    这是组件中的方法：hello
A2类被实例化了
自动运行方法：PostConstruct
    这是组件中的方法：hello
自动运行方法：静态方法
    不能通过容器注入方法。
A1类被实例化了
2023-08-04 10:48:19.885  INFO 21316 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-08-04 10:48:19.903  INFO 21316 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-08-04 10:48:19.910  INFO 21316 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : Started DbManagerApplication in 1.02 seconds (JVM running for 1.836)
启动时自动执行 ApplicationRunner 的 run 方法
    这是组件中的方法：hello
这是传过来的参数[name],参数值为[zunmx] 
这是传过来sourceArgs[-a] 
这是传过来sourceArgs[-b] 
这是传过来sourceArgs[-c] 
这是传过来sourceArgs[--name=zunmx]

貌似顺序和文件名有关

那么如果他们之间有依赖关系，那么spring会如何处理呢？
我们稍微改一下AutoRun2 3 4，给他们都加上下面的代码

public void hello() {
        System.out.println("        hello2 或者 3 或者 4");
    }

执行结果

[#] initialize starting
11:02:08.604 [Thread-1] DEBUG org.springframework.boot.devtools.restart.classloader.RestartClassLoader - Created RestartClassLoader org.springframework.boot.devtools.restart.classloader.RestartClassLoader@45c59d95
[#] initialize starting

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::               (v2.7.14)

2023-08-04 11:02:08.801  INFO 30172 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : Starting DbManagerApplication using Java 1.8.0_151 on ZUNMX with PID 30172 (E:\StudyCode\Java\DBManager\target\classes started by 36083 in E:\StudyCode\Java\DBManager)
2023-08-04 11:02:08.802  INFO 30172 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : No active profile set, falling back to 1 default profile: "default"
2023-08-04 11:02:08.827  INFO 30172 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2023-08-04 11:02:08.827  INFO 30172 --- [  restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2023-08-04 11:02:09.325  INFO 30172 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-08-04 11:02:09.330  INFO 30172 --- [  restartedMain] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-08-04 11:02:09.330  INFO 30172 --- [  restartedMain] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.78]
2023-08-04 11:02:09.367  INFO 30172 --- [  restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-08-04 11:02:09.367  INFO 30172 --- [  restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 540 ms
A1自动运行方法：静态方法
A1    不能通过容器注入方法。
A1类被实例化了
A2类被实例化了
A3类被实例化了
A4类被实例化了
A3自动运行方法：实现ServletContextAware接口
    这是组件中的方法：hello
        hello4
A2自动运行方法：PostConstruct
    这是组件中的方法：hello
        hello3
2023-08-04 11:02:09.545  INFO 30172 --- [  restartedMain] o.s.b.d.a.OptionalLiveReloadServer       : LiveReload server is running on port 35729
2023-08-04 11:02:09.565  INFO 30172 --- [  restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-08-04 11:02:09.571  INFO 30172 --- [  restartedMain] t.zunmx.dbmanager.DbManagerApplication   : Started DbManagerApplication in 0.962 seconds (JVM running for 1.664)
A4启动时自动执行 ApplicationRunner 的 run 方法
    这是组件中的方法：hello
A4这是传过来的参数[name],参数值为[zunmx] 
A4这是传过来sourceArgs[-a] 
A4这是传过来sourceArgs[-b] 
A4这是传过来sourceArgs[-c] 
A4这是传过来sourceArgs[--name=zunmx] 
[#] initialize done

完整代码实例

AutoRun.java

package top.zunmx.dbmanager.utils;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component()
public class AutoRun {
    @Autowired
    private InsideDBO insideDBO;

    public AutoRun(){
        System.out.println("A1类被实例化了");
    }
    static {
        System.out.println("A1自动运行方法：静态方法");
        System.out.println("A1    不能通过容器注入方法。");
    }

    public void hello(){
        System.out.println("        hello1");
    }
}

AutoRun2.java

package top.zunmx.dbmanager.utils;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component()
public class AutoRun {
    @Autowired
    private InsideDBO insideDBO;

    public AutoRun(){
        System.out.println("A1类被实例化了");
    }
    static {
        System.out.println("A1自动运行方法：静态方法");
        System.out.println("A1    不能通过容器注入方法。");
    }

    public void hello(){
        System.out.println("        hello1");
    }
}

AutoRun3.java

package top.zunmx.dbmanager.utils;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.context.ServletContextAware;

import javax.servlet.ServletContext;

@Component
public class AutoRun3 implements ServletContextAware {
    @Autowired
    private InsideDBO insideDBO;
    @Autowired
    private AutoRun4 autoRun4;

    public AutoRun3(){
        System.out.println("A3类被实例化了");
    }
    @Override
    public void setServletContext(ServletContext servletContext) {
        System.out.println("A3自动运行方法：实现ServletContextAware接口");
        insideDBO.hello();
        autoRun4.hello();
    }

    public void hello(){
        System.out.println("        hello3");
    }
}

AutoRun4.java

package top.zunmx.dbmanager.utils;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.stereotype.Component;

import java.util.Set;

@Component
public class AutoRun4 implements ApplicationRunner {

    @Autowired
    private InsideDBO insideDBO;

    public AutoRun4(){

        System.out.println("A4类被实例化了");
    }
    @Override
    public void run(ApplicationArguments args) throws Exception {
        System.out.println("A4启动时自动执行 ApplicationRunner 的 run 方法");
        insideDBO.hello();
        Set<String> optionNames = args.getOptionNames();
        for (String optionName : optionNames) {
            System.out.printf("A4这是传过来的参数[%s],参数值为%s \n", optionName, args.getOptionValues(optionName));
        }
        String[] sourceArgs = args.getSourceArgs();
        for (String sourceArg : sourceArgs) {
            System.out.printf("A4这是传过来sourceArgs[%s] \n", sourceArg);
        }
    }


    public void hello(){
        System.out.println("        hello4");
    }
}

InsideDBO.java

package top.zunmx.dbmanager.utils;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component
@Scope("singleton")
public class InsideDBO {

    public void hello() {
        System.out.println("    这是组件中的方法：hello");
    }
}

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