使用IntelliJ部署支持嵌入式tomcat的spring-boot应用程序

Question

Caused by: java.lang.IllegalStateException: Failed to introspect annotated methods on class org.springframework.boot.web.support.SpringBootServletInitializer
    at org.springframework.core.type.StandardAnnotationMetadata.getAnnotatedMethods(StandardAnnotationMetadata.java:163) ~[spring-core-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.retrieveBeanMethodMetadata(ConfigurationClassParser.java:380) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.doProcessConfigurationClass(ConfigurationClassParser.java:314) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.processConfigurationClass(ConfigurationClassParser.java:245) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:198) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    at org.springframework.context.annotation.ConfigurationClassParser.parse(ConfigurationClassParser.java:167) ~[spring-context-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    ... 17 common frames omitted
Caused by: java.lang.NoClassDefFoundError: javax/servlet/ServletContext
    at java.lang.Class.getDeclaredMethods0(Native Method) ~[na:1.8.0_144]
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2701) ~[na:1.8.0_144]
    at java.lang.Class.getDeclaredMethods(Class.java:1975) ~[na:1.8.0_144]
    at org.springframework.core.type.StandardAnnotationMetadata.getAnnotatedMethods(StandardAnnotationMetadata.java:152) ~[spring-core-4.3.8.RELEASE.jar:4.3.8.RELEASE]
    ... 22 common frames omitted
Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletContext
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_144]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_144]
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335) ~[na:1.8.0_144]
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_144]
    ... 26 common frames omitted

我使用的是IntelliJ IDEA 2017.2（只是在构建为IDEA-IU-172.3317.76的情况下），作为一个SSCCE，让我们使用spring-boot的入门示例，并应用为传统部署提出的更改（第一个链接），我们将得到以下文件

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.springframework</groupId>
    <artifactId>gs-spring-boot</artifactId>
    <version>0.1.0</version>
    <packaging>war</packaging>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.6.RELEASE</version>
    </parent>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
            <scope>provided</scope>
        </dependency>
    </dependencies>

    <properties>
        <java.version>1.8</java.version>
    </properties>


    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

那么我们将有application.java

package hello;

import java.util.Arrays;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.support.SpringBootServletInitializer;
import org.springframework.context.ApplicationContext;

@SpringBootApplication
public class Application extends SpringBootServletInitializer {

    public static void main(String[] args) {
        ApplicationContext ctx = SpringApplication.run(Application.class, args);

        System.out.println("Let's inspect the beans provided by Spring Boot:");

        String[] beanNames = ctx.getBeanDefinitionNames();
        Arrays.sort(beanNames);
        for (String beanName : beanNames) {
            System.out.println(beanName);
        }
    }

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(Application.class);
    }

}

package hello;

import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.bind.annotation.RequestMapping;

@RestController
public class HelloController {

    @RequestMapping("/")
    public String index() {
        return "Greetings from Spring Boot!";
    }

}

Answer 1

注意：此答案参考了Spring V1.5.6.版本（当前版本）的文档

分析：

从IJ运行main类就像从命令行执行应用程序一样。因此，类路径将只包括compile和runtime范围的依赖项。provided表示在编译期间需要它，但您希望JDK或容器在运行时为应用程序提供它：

默认情况下，重新打包和运行目标都将包括项目中定义的任何提供的依赖项。基于引导的项目应将提供的依赖项视为运行应用程序所需的容器依赖项。

结论和解决方案：

所以这是一个类路径配置问题。正如您提到的，对于war打包或传统部署，您应该排除嵌入式servlet容器。但是，为了能够在开发过程中运行应用程序，您需要嵌入式容器。

作为一种解决方案或解决方案，您至少有以下2个选项：

<profiles>
    <profile>
        <id>dev</id>
        <dependencies>
            <dependency>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-starter-tomcat</artifactId>
            </dependency>
        </dependencies>
    </profile>
</profiles>