Spring 启动 REST API 404 错误

Question

I am trying to create a basic spring boot application (JDK 1.8) with a REST API . The following is my application code

package org.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan("org.demo")
@EnableAutoConfiguration
public class DemoApplication {

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

I have added a simple controller as follows

    package org.demo.controllers;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

@RestController(value = "/hello")
public class HelloController {

    @GetMapping
    @ResponseBody
    public String hello() {
        return "Hello";
    }
}

The POM file of my project is as follows

    <?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.demo</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>2.0.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

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

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

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

    </dependencies>

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


</project>

When I run this application, it starts successfully. However, when I try to hit the URL localhost:8080 or loclahost:8080/hello, I get the 404 error message

The following are the startup logs :: Spring Boot :: (v2.0.1.RELEASE)

2018-04-24 21:51:38.888  INFO 12068 --- [           main] org.demo.DemoApplication                 : Starting DemoApplication on DESKTOP-G2QR23G with PID 12068 (I:\demo\spring-boot\demo\target\classes started by chirayu in I:\demo\spring-boot\demo)
2018-04-24 21:51:38.892  INFO 12068 --- [           main] org.demo.DemoApplication                 : No active profile set, falling back to default profiles: default
2018-04-24 21:51:38.970  INFO 12068 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@5745ca0e: startup date [Tue Apr 24 21:51:38 IST 2018]; root of context hierarchy
2018-04-24 21:51:39.617  INFO 12068 --- [           main] f.a.AutowiredAnnotationBeanPostProcessor : JSR-330 'javax.inject.Inject' annotation found and supported for autowiring
2018-04-24 21:51:39.999  INFO 12068 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2018-04-24 21:51:40.030  INFO 12068 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-04-24 21:51:40.030  INFO 12068 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.29
2018-04-24 21:51:40.043  INFO 12068 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [I:\Program Files\Java\jdk1.8.0_66\bin;C:\WINDOWS\Sun\Java\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\ProgramData\Oracle\Java\javapath;C:\Program Files (x86)\Intel\iCLS Client\;C:\Program Files\Intel\iCLS Client\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files\Intel\Intel(R) Management Engine Components\DAL;C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files\Intel\Intel(R) Management Engine Components\IPT;C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\System32\Wbem;C:\WINDOWS\System32\WindowsPowerShell\v1.0\;I:\Program Files\Java\jdk1.8.0_66\bin;I:\Program Files\nodejs\;C:\Program Files (x86)\GtkSharp\2.12\bin;C:\Program Files (x86)\Skype\Phone\;I:\MinGW\bin;C:\Program Files (x86)\MySQL\MySQL Fabric 1.5 ^& MySQL Utilities 1.5\;C:\Program Files (x86)\MySQL\MySQL Fabric 1.5 ^& MySQL Utilities 1.5\Doctrine extensions for PHP\;I:\Program Files (x86)\maven\apache-maven-3.3.9\bin\;I:\Program Files (x86)\Heroku\bin;C:\Program Files (x86)\git\cmd;I:\Program Files\Git\cmd;I:\Program Files\PostgreSQL\9.6\bin;I:\RailsInstaller\Git\cmd;I:\RailsInstaller\Ruby2.2.0\bin;I:\Program Files (x86)\Python\Scripts\;I:\Program Files (x86)\Python\;C:\Users\chirayu\AppData\Roaming\npm;C:\Users\chirayu\AppData\Local\Microsoft\WindowsApps;I:\Program Files (x86)\Microsoft VS Code\bin;;.]
2018-04-24 21:51:40.164  INFO 12068 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-04-24 21:51:40.164  INFO 12068 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 1198 ms
2018-04-24 21:51:40.215  INFO 12068 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-04-24 21:51:40.598  INFO 12068 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-04-24 21:51:40.633  INFO 12068 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2018-04-24 21:51:40.638  INFO 12068 --- [           main] org.demo.DemoApplication                 : Started DemoApplication in 2.2 seconds (JVM running for 2.797)

I am not sure what I might be missing. Please help.

Answer 1

I got the solution. It was due to package visibility. Main class was not able to found package in which controller class is present. So added all classes under same package. You can also place application class one level up. Got help from below link:

Spring Boot: Cannot access REST Controller on localhost (404)

Answer 2

Test as follow... did the trick for me remove the path from the notation @RestController then add the path @GetMapping notation as follow @GetMapping("/hello") test http://localhost:8080/hello you should get a correct response in order to have a response for this request http://localhost:8080/hello/hello need to add the follow:

@RestController
@RequestMapping(value = "/hello")

Answer 3

change to :

@RestController
@RequestMapping(value = "hello-controller")
public class HelloController {

@GetMapping(value="hello")
@ResponseBody
public String hello() {
    return "Hello";
}
}

so you can use your api from : localhost:8080/hello-controller/hello

1. value in @RequestMapping below @RestController is define your class address.
2. value in @GetMapping is for your API address.

Hope this explanation help you.