Question

我正在尝试使用Spring Boot实现简单的演示MVC应用程序，但在执行应用程序时出现404错误。 uri是“http://localhost:8080/”，用于显示名为circle的表中的所有行。

Spring Boot：1.3.3.RELEASE
Java版本：1.8.0_65
数据库：Apache Derby 10.12.1.1

Maven Java Project：

Application.java

package com.nomad.dubbed.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Application  {

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

}

CircleController.java

package com.nomad.dubbed.controller;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.nomad.dubbed.dao.CircleService;
import com.nomad.dubbed.model.Circle;

@RestController
@RequestMapping("/")
public class CircleController {
    @Autowired
    private CircleService circleService;

    @RequestMapping(method=RequestMethod.GET)
    public List<Circle> getAll() {
        return circleService.getAll();
    }

}

CircleRepository.java

package com.nomad.dubbed.dao;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.stereotype.Repository;

import com.nomad.dubbed.model.Circle;

@Repository
public interface CircleRepository extends JpaRepository<Circle, Integer> {

}

CircleService.java

package com.nomad.dubbed.dao;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.nomad.dubbed.model.Circle;

@Service
public class CircleService {
    @Autowired
    private CircleRepository circleRepository;

    @Transactional(propagation=Propagation.REQUIRED)
    public List<Circle> getAll(){
        return circleRepository.findAll();
    }

}

Circle.java

package com.nomad.dubbed.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

@Entity
@Table(name="circle")
public class Circle {
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    private String name;

    public Circle(int id, String name) {
        super();
        this.id = id;
        this.name = name;
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }

}

application.properties

spring.datasource.url=jdbc:derby://localhost:1527/db
spring.datasource.driverClassName=org.apache.derby.jdbc.ClientDriver

logging.level.org.springframework.web:DEBUG
logging.level.org.hibernate:DEBUG

的pom.xml

<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>com.nomad.dubbed</groupId>
  <artifactId>spring-boot-mvc</artifactId>
  <version>0.0.1-SNAPSHOT</version>


    <properties>
        <derby-client.version>10.11.1.1</derby-client.version>
    </properties>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.3.3.RELEASE</version>
        <relativePath />
    </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-remote-shell</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>

        <dependency>
            <groupId>org.apache.derby</groupId>
            <artifactId>derbyclient</artifactId>
            <version>${derby-client.version}</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <build>
        <finalName>spring-boot-mvc</finalName>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

数据库已启动并正在运行，表圈中有5行：

默认的uri（/ beans，/ health ..）工作正常，但无法识别已实现的控制器。控制台中没有显示错误，下面是我发送请求后在控制台中打印的日志转储。

2016-05-03 14:17:26.594 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : DispatcherServlet with name 'dispatcherServlet' processing GET request for [/]
2016-05-03 14:17:26.596 DEBUG 659 --- [nio-8080-exec-3] s.w.s.m.m.a.RequestMappingHandlerMapping : Looking up handler method for path /
2016-05-03 14:17:26.596 DEBUG 659 --- [nio-8080-exec-3] s.w.s.m.m.a.RequestMappingHandlerMapping : Did not find handler method for [/]
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.w.s.handler.SimpleUrlHandlerMapping  : Matching patterns for request [/] are [/**]
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.w.s.handler.SimpleUrlHandlerMapping  : URI Template variables for request [/] are {}
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapping [/] to HandlerExecutionChain with handler [ResourceHttpRequestHandler [locations=[ServletContext resource [/], class path resource [META-INF/resources/], class path resource [resources/], class path resource [static/], class path resource [public/]], resolvers=[org.springframework.web.servlet.resource.PathResourceResolver@6c13019c]]] and 1 interceptor
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Last-Modified value for [/] is: -1
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Null ModelAndView returned to DispatcherServlet with name 'dispatcherServlet': assuming HandlerAdapter completed request handling
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Successfully completed request
2016-05-03 14:17:26.597 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : DispatcherServlet with name 'dispatcherServlet' processing GET request for [/error]
2016-05-03 14:17:26.600 DEBUG 659 --- [nio-8080-exec-3] s.w.s.m.m.a.RequestMappingHandlerMapping : Looking up handler method for path /error
2016-05-03 14:17:26.600 DEBUG 659 --- [nio-8080-exec-3] s.w.s.m.m.a.RequestMappingHandlerMapping : Returning handler method [public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)]
2016-05-03 14:17:26.600 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Last-Modified value for [/error] is: -1
2016-05-03 14:17:26.601 DEBUG 659 --- [nio-8080-exec-3] o.s.w.s.v.ContentNegotiatingViewResolver : Requested media types are [text/html, text/html;q=0.8] based on Accept header types and producible media types [text/html])
2016-05-03 14:17:26.601 DEBUG 659 --- [nio-8080-exec-3] o.s.w.s.v.ContentNegotiatingViewResolver : Returning [org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$SpelView@2f5f8d71] based on requested media type 'text/html'
2016-05-03 14:17:26.601 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Rendering view [org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$SpelView@2f5f8d71] in DispatcherServlet with name 'dispatcherServlet'
2016-05-03 14:17:26.601 DEBUG 659 --- [nio-8080-exec-3] o.s.web.servlet.DispatcherServlet        : Successfully completed request

Answer 1

为您的控制器使用不同的网址。＆＃34; /＆＃34;在spring-boot中映射到位于META-INF / resources和src / main / resources / static /中的静态资源。

编辑：忘记上面并在您的应用程序类中执行以下操作：

<强> Application.java

package com.nomad.dubbed.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@ComponentScan("com.nomad.dubbed")
public class Application  {

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

}

弹簧靴组件扫描未发现您的其余控制器。根据此文档http://docs.spring.io/spring-boot/docs/current/reference/html/ ... spring扫描包含@SpringBootApplication批注的类所在的包下面的包。您的控制器位于并行包中。

Answer 2

我们不应将@ComponentScan批注与@SpringBootApplication一起使用，因为这不是正确的做法。 @SpringBootApplication是03注释@ ComponentScan，@ EnableAutoConfiguration和@Configuration的组合。

答案是Main类，具有@SpringBootApplication批注的应该位于父/超级包中。例如-com.spring.learning是父包，而child是 com.spring.learning.controller，com.spring.learning.service，com.spring.learning.pojo 因此，它将扫描其程序包和子程序包。这是正确的做法。项目布局或结构是Spring Boot中一个突出的概念。

Answer 3

您可以尝试添加@ResponseBody注释

@RequestMapping(method=RequestMethod.GET)
@ResponseBody
    public List<Circle> getAll() {
        return circleService.getAll();
    }

Answer 4

我必须研究更多为什么spring-boot无法识别具有原始包结构的控制器。我将所有java类转储到一个包中，最后运行了演示项目。

修改后的Java项目结构：

还修改了CircleController.java类。我从圆桌会议中删除了所有记录，但未提及具体的请求方法method=RequestMethod.GET。

package com.nomad.dubbed.app;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class CircleController {
    @Autowired
    private CircleService circleService;

    @RequestMapping(value="/circles", method=RequestMethod.GET)
    public List<Circle> getAll() {
        return circleService.getAll();
    }

}

Answer 5

我遇到了同样的问题，我在Application类中添加了 @ComponentScan（basePackages =＆＃34; package.name＆＃34;）。之后，我的休息控制器得到了认可。

package com.nomad.dubbed.app;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@ComponentScan(basePackages = "com.spring.basepkg")
public class Application  {

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

}

Answer 6

在我看来，当我们将组件扫描留给Spring时，就会出现这种可见性问题，它具有使用标准约定查找类的特殊方式。在这种情况下，由于Starter类（应用程序）位于com.nomad.dubbed.app软件包中，因此将Controller置于较低级别将有助于Spring使用默认的组件扫描机制查找类。将CircleController放在com.nomad.dubbed.app.controller下应该可以解决此问题。

Answer 7

我有一个类似的问题。在Application类上添加注释 @SpringBootApplication（scanBasePackages = {“ com.nomad.dubbed”}）很适合我。

Answer 8

这是怎么回事。

@SpringBootApplication注释是@Configuration @EnableAutoConfiguration @ComponentScan的组合。

@ComponentScan（不带参数）告诉框架在同一包及其子包中查找组件/ bean。

用Application注释的@SpringBootApplication类在包com.nomad.dubbed.app中。因此，它将扫描该软件包及其下的子软件包（如com.nomad.dubbed.app.*）。但是您的CircleController位于软件包com.nomad.dubbed.controller中，默认情况下不会对其进行扫描。您的存储库也超出了默认的扫描程序包，因此spring框架也不会发现它们。

那现在该怎么办？，您有两个选择。

选项1

将Application类移动到顶部目录（程序包）。对于您的com.nomad.dubbed包。然后，由于所有控制器和其他存储库都在子包中，因此框架会发现它们。

选项2

将@ComponentScan注释与basePackages参数一起使用，并与@SpringBootApplication类中的Application一起使用，如下所示。

@SpringBootApplication
@ComponentScan(basePackages="com.nomad.dubbed")
public class Application  {

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

Answer 9

实际上springboots会扫描您的核心软件包下的所有组件，例如：

package com.nomad.dubbed.app;

如果您在com.nomad.dubbed.app.controllers，com.nomad.dubbed.app.services，com.nomad.dubbed.app.dao下添加控制器，服务和dao软件包。

然后，您可以轻松地运行rest控制器，但是如果您将所有与springboot核心软件包平行的软件包（例如com.nomad.dubbed.controllers，com.nomad.dubbed.services）添加。

然后您需要扫描@ComponentScan（{“ com.nomad.dubbed.controllers”，“ com.nomad.dubbed.services”}）

如果您选择组件，那么还必须扫描springboot应用程序软件包。

最好的方法是在名为boot.app.xyz的春季启动应用程序下创建所有软件包。

Rest Controller无法识别Spring Boot App中的GET请求

9 个答案: