为什么org.springframework.boot导入不起作用，但是org.springframework.web呢？

Question

我正在尝试构建这个RESTful服务示例：https://spring.io/guides/gs/rest-service/ GreetingController.java导入没有错误：

package hello;

import java.util.concurrent.atomic.AtomicLong;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class GreetingController {
    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @RequestMapping(value = "/greeting", method = RequestMethod.GET)
    public Greeting greeting(@RequestParam(value = "name", required = false, defaultValue = "World") String name) {
        return new Greeting(counter.incrementAndGet(), String.format(template, name));
    }
}

但是Application.java我得到了：

我收到以下错误：The import org.springframework.boot cannot be resolved.我已将Spring 4库添加到包含所有jar的项目中。为什么第一次导入工作而第二次导入不起作用？ @ComponentScan注释我也没有错误，但是@EnableAutoConfiguration注释出错了。

Answer 1

我终于努力让它发挥作用。问题出在Spring网站上发布的pom.xml文件中：它需要一些修改。这是我使用的版本：

<?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-rest-service</artifactId>
    <version>0.1.0</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.1.6.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
    <properties>
        <start-class>hello.Application</start-class>
    </properties>
    <build>
        <plugins>
            <plugin>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>2.3.2</version>
                <configuration>
                    <source>1.7</source>
                    <target>1.7</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-releases</id>
            <url>http://repo.spring.io/libs-release</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-releases</id>
            <url>http://repo.spring.io/libs-release</url>
        </pluginRepository>
    </pluginRepositories>
</project>

然后我继续用Maven，Eclipse插件构建项目。有一个进程占据了8080端口所以我杀了它。我运行了我从Maven构建的.jar，它运行了！谢谢你们指出这个问题。我需要Maven来定义依赖项而不是手动包含库。我想我迟早要学习Maven。 ：）

Answer 2

<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/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.dugu.acc.dev</groupId>
    <artifactId>FirstSpringBootApp</artifactId>
    <packaging>war</packaging>
    <version>0.0.1-SNAPSHOT</version>
    <name>FirstSpringBootApp Maven Webapp</name>
    <url>http://maven.apache.org</url>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.1.6.RELEASE</version>
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
    </dependencies>
    <build>
        <finalName>FirstSpringBootApp</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

它对我有用。