java - Spring Boot 不起作用？

Question

我已经使用命令生成了一个标准的 Spring Boot 示例

spring init

结果是一个普通的 Java 项目，其 pom 如下

 <?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.test</groupId>
    <artifactId>demo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>demo</name>
    <description>Demo project for Spring Boot</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.2.3.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <start-class>demo.DemoApplication</start-class>
        <java.version>1.7</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

</project>

当我击中

spring run src/main/java/demo/DemoApplication.java

它会显示一条错误消息，例如

 org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'propertySourceBootstrapConfiguration': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.List org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration.propertySourceLocators; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'configServicePropertySource' defined in class org.springframework.cloud.bootstrap.config.PropertySourceBootstrapConfiguration$PropertySourceLocatorConfiguration: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.config.client.ConfigServicePropertySourceLocator]: Factory method 'configServicePropertySource' threw exception; nested exception is java.lang.NoClassDefFoundError: org/springframework/web/client/HttpServerErrorException

我无法解释。 我做错了什么？

Answer 1

这个问题的标签之一是 spring-mvc，所以我假设您想使用 Web Spring 功能。 要启用 Spring Web 功能，您需要将此 Spring Boot 依赖项添加到 POM 中:

   <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>

我之前没有使用过Spring CLI，因此我不知道为什么它没有生成带有Web依赖项的项目。但我敢打赌，您需要以某种方式明确指定要生成 Web 项目。

因此，您可能生成了没有 Web 依赖项的普通 Spring Boot 项目，并在 application.properties 中添加了一些与 Web 相关的配置。因此 Spring Boot 自动配置器会尝试在您的类路径上查找 Web 依赖项。