在使用Spring Boot的REST Web服務中的GET請求期間，如何修復``HTTP-404''錯誤

Question

我的示例Spring Boot REST Web服務給出了404錯誤，我不確定出了什么問題

package com.in28minutes.springboot.studentservices;
@SpringBootApplication
public class StudentServicesApplication {

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

}

package com.in28minutes.springboot.controller;
@RestController
public class StudentController {

@Autowired
private StudentService studentService;

@GetMapping("/students/{studentId}/courses")
public List<Course> retrieveCoursesForStudent(@PathVariable String 
    studentId) {
    return studentService.retrieveCourses(studentId);
}

@GetMapping("/students/{studentId}/courses/{courseId}")
public Course retrieveDetailsForCourse(@PathVariable String studentId,
        @PathVariable String courseId) {
    return studentService.retrieveCourse(studentId, courseId);
}

}

POSTMan REST請求發件人的我的請求： http：// localhost：8080 / students / stu1 / courses / course1

的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>
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.1.1.RELEASE</version>
    <relativePath/> <!-- lookup parent from repository -->
 </parent>
 <groupId>com.in28minutes.springboot</groupId>
 <artifactId>student-services</artifactId>
 <version>0.0.1-SNAPSHOT</version>
 <name>student-services</name>
 <description>Demo project for Spring Boot</description>

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

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

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
    </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>

響應：

{“ timestamp”：“ 2018-12-28T02：48：00.185 + 0000”，“ status”：404，“ error”：“ Not Found”，“ message”：“無可用消息”，“ path”：“ /學生/ stu1 /課程/課程1“}

Answer 1

假設您在不同的包com.in28minutes.springboot.controller;具有Controller類com.in28minutes.springboot.controller; 和Spring boot主類在不同的com.in28minutes.springboot.studentservices;包中com.in28minutes.springboot.studentservices;

@SpringBootApplication

默認情況下， @SpringBootApplication將僅從聲明此批注的類的包中掃描。

這是一個方便注釋，等效於聲明@ Configuration，@ EnableAutoConfiguration和@ComponentScan。

如果未定義特定的程序包，則將從聲明此批注的類的程序包中進行掃描。

使用@ComponentScan掃描控制器程序包

@ComponentScan(basePackages = {"com.in28minutes.springboot.controller"})
 @SpringBootApplication
 public class StudentServicesApplication {

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

更多信息： 參考

Answer 2

問題已解決，需要將@Component和主應用程序類中的@ComponentScan一起添加到Service類中：

package com.in28minutes.springboot.service;

import java.util.List;
import java.util.Map;
import java.util.stream.Collectors;

import org.springframework.stereotype.Component;

import com.in28minutes.springboot.model.Course;
import com.in28minutes.springboot.model.Student;

@Component
public class StudentService {

public List<Course> retrieveCourses(String studentId) {
    Map<String, Course> courses = Student.getStudentObj(studentId).getCourses();
    List<Course> courseList = 
    courses.values().parallelStream().collect(Collectors.toList());
    return courseList;
 }

 public Course retrieveCourse(String studentId, String courseId) {
    return Student.getStudentObj(studentId).getCourses().get(courseId);
 }

}

package com.in28minutes.springboot;

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

@SpringBootApplication 
@ComponentScan("com.in28minutes.springboot")
public class StudentServicesApplication {

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

}