简介:本文将帮助您使用 Spring Boot 创建简单的 REST 服务。
你将学习
本教程使用的 rest 服务
在本教程中,我们将使用适当的 URI 和 HTTP 方法创建三个服务:
@GetMapping(“/ students / {studentId} / courses”):您可以使用请求方法 Get 和示例 uri / students / Student1 / courses 来查询特定学生已注册的课程。
@GetMapping(“/students/{studentId}/courses/{courseId}”):您可以使用请求方法 Get 和示例 uri / students / Student1 / courses / Course1 获取特定学生的特定课程。
@PostMapping(“/students/{studentId}/courses”) :您可以通过向 UURI /students/Student1/courses 发送 POST 请求来为学生注册一门课程
您将需要的工具
完整的 spring booot rest Maven 项目代码示例子
我们的 Github 存储库包含所有代码示例 - https://github.com/in28minutes/in28minutes.github.io/tree/master/code-zip-files
带有单元和集成测试的 REST 服务
Website-springbootrestservices-simplerestserviceswithunitandintegrationtests.zip
什么是 REST?
REST 代表 REpresentational State Transfer。REST 指定了一组体系结构约束。任何满足以下这些条件的服务都称为 RESTful 服务。
RESTful Web Service 的五个重要条件:
理查森成熟度模型
Richardson 成熟度模型用于识别 Restful Web Service 的成熟度级别。以下是不同级别和特点:
级别 0:以 REST 风格公开 SOAP Web 服务。公开的操作使用 REST 服务(http:// server / getPosts,http:// server / deletePosts,http:// server / doThis,http:// server / doThat 等)。
级别 1:使用正确的 URI(使用名词)公开资源。例如:http:// server / accounts,http:// server / accounts / 10。但是,HTTP 方法并未使用。
级别 2:资源使用正确的 URI + HTTP 方法。例如,要更新一个账户,你需要做一个 PUT。创建一个帐户,你做一个 POST。Uri 看起来像 posts/1/comments/5 和 accounts/1/friends/1.
等级 3:HATEOAS (Hypermedia as the engine of application state)。您不仅可以了解所请求的信息,还可以了解服务消费者可以采取的下一个可能的操作。当请求有关 Facebook 用户的信息时,REST 服务可以返回用户详细信息以及有关如何获取他最近的帖子,如何获取他最近的评论以及如何检索他朋友的列表的信息。
使用适当的请求方法
始终使用 HTTP 方法。有关每种 HTTP 方法的最佳做法如下所述:
GET:不应该更新任何东西。应该是幂等的(多次调用相同的结果)。可能的返回码 200(OK)+ 404(NOT FOUND)+400(BAD REQUEST)
POST:应该创建新的资源。理想情况下返回 JSON 和链接到新创建的资源。尽可能使用相同的返回码。另外:返回码 201(创建)是可能的。
PUT:更新已知资源。例如:更新客户详细信息。可能的返回码:200(OK)
DELETE:用于删除资源。
项目结构
以下屏幕截图显示了我们将创建的项目的结构。
一些细节:
使用 Spring Initializr 引导创建 REST 服务
用 Spring Initializr 创建一个 REST 服务是非常的容易小菜一碟。我们将使用 Spring Web MVC 作为我们的 web 层框架。
Spring Initializr http://start.spring.io/ 是引导创建 Spring Boot 项目的好工具。
如上图所示,必须执行以下步骤
启动 Spring Initializr 并选择以下内容
选择 com.in28minutes.springboot 为 Group
选择 student-services 为 Artifact
选择以下依赖项
点击生成项目。
将项目导入 Eclipse。文件 - > 导入 - > 现有的 Maven 项目。
如果你想了解这个项目的所有文件,你可以继续向下阅读。
应用业务层实现
所有应用都需要数据。我们将使用 ArrayList 这种内存数据存储,而不是与真实数据库交互。
一名学生可以参加多门课程。课程有一个 ID,名称,说明和完成课程需要完成的步骤列表。学生有一个身份证,姓名,说明和他 / 她目前注册的课程列表。StudentService 提供以下公开方法
public List retrieveAllStudents() - 检索所有学生的详细信息
public Student retrieveStudent(String studentId) - 检索特定的学生详细信息
public List retrieveCourses(String studentId) - 检索学生注册的所有课程
public Course retrieveCourse(String studentId, String courseId) - 检索学生注册的特定课程的详细信息
public Course addCourse(String studentId, Course course) - 为现有学生添加课程
请参阅下面这些文件,具体的实现服务类 StudentService 和模型类 Course 和 Student。
添加几个 GET Rest 服务
Rest 服务 StudentController 暴露了几个 get 服务。
package com.in28minutes.springboot.controller;import java.util.List;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.RestController;import com.in28minutes.springboot.model.Course;import com.in28minutes.springboot.service.StudentService;@RestControllerpublic class StudentController {@Autowiredprivate 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);}}使用 Postman 执行获取服务
我们将向 http:// localhost:8080 / students / Student1 / courses / Course1 发起请求以测试该服务。回应如下所示。
{ "id": "Course1", "name": "Spring", "description": "10 Steps", "steps": [ "Learn Maven", "Import Project", "First Example", "Second Example" ]}下面的图片显示了我们如何执行 Postman 的 Get Service - 我最喜欢的运行 rest 服务的工具。
添加 POST Rest 服务
当资源创建成功时,POST 服务应该返回创建的状态(201)。
@PostMapping("/students/{studentId}/courses")public ResponseEntity<Void> registerStudentForCourse(@PathVariable String studentId, @RequestBody Course newCourse) {Course course = studentService.addCourse(studentId, newCourse);if (course == null)return ResponseEntity.noContent().build();URI location = ServletUriComponentsBuilder.fromCurrentRequest().path("/{id}").buildAndExpand(course.getId()).toUri();return ResponseEntity.created(location).build();}执行 POST Rest 服务
示例请求如下所示。它包含了学生注册课程的所有细节。
{ "name": "Microservices", "description": "10 Steps", "steps": [ "Learn How to Break Things Up", "Automate the hell out of everything", "Have fun" ]}下图显示了我们如何从 Postman 执行 Post 服务 - 我最喜欢的运行 rest 服务的工具。确保你去 Body 选项卡并选择 raw。从下拉菜单中选择 JSON。将上述请求复制到 body 中。
我们使用的 URL 是 http:// localhost:8080 / students / Student1 / courses。
完整的代码示例
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><groupId>com.in28minutes.springboot</groupId><artifactId>student-services</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>student-services</name><description>Demo project for Spring Boot</description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.4.4.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-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>
src/main/java/com/in28minutes/springboot/controller/StudentController.java
import java.net.URI;import java.util.List;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.http.ResponseEntity;import org.springframework.web.bind.annotation.GetMapping;import org.springframework.web.bind.annotation.PathVariable;import org.springframework.web.bind.annotation.PostMapping;import org.springframework.web.bind.annotation.RequestBody;import org.springframework.web.bind.annotation.RestController;import org.springframework.web.servlet.support.ServletUriComponentsBuilder;import com.in28minutes.springboot.model.Course;import com.in28minutes.springboot.service.StudentService;@RestControllerpublic class StudentController {@Autowiredprivate 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);}@PostMapping("/students/{studentId}/courses")public ResponseEntity<Void> registerStudentForCourse(@PathVariable String studentId, @RequestBody Course newCourse) {Course course = studentService.addCourse(studentId, newCourse);if (course == null)return ResponseEntity.noContent().build();URI location = ServletUriComponentsBuilder.fromCurrentRequest().path("/{id}").buildAndExpand(course.getId()).toUri();return ResponseEntity.created(location).build();}}src/main/java/com/in28minutes/springboot/model/Course.java
import java.util.List;public class Course {private String id;private String name;private String description;private List<String> steps;// Needed by Caused by: com.fasterxml.jackson.databind.JsonMappingException:// Can not construct instance of com.in28minutes.springboot.model.Course:// no suitable constructor found, can not deserialize from Object value// (missing default constructor or creator, or perhaps need to add/enable// type information?)public Course() {}public Course(String id, String name, String description, List<String> steps) {super();this.id = id;this.name = name;this.description = description;this.steps = steps;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getDescription() {return description;}public String getName() {return name;}public List<String> getSteps() {return steps;}@Overridepublic String toString() {return String.format("Course [id=%s, name=%s, description=%s, steps=%s]", id, name,description, steps);}@Overridepublic int hashCode() {final int prime = 31;int result = 1;result = prime * result + ((id == null) ? 0 : id.hashCode());return result;}@Overridepublic boolean equals(Object obj) {if (this == obj)return true;if (obj == null)return false;if (getClass() != obj.getClass())return false;Course other = (Course) obj;if (id == null) {if (other.id != null)return false;} else if (!id.equals(other.id))return false;return true;}}src/main/java/com/in28minutes/springboot/model/Student.java
package com.in28minutes.springboot.model;import java.util.List;public class Student {private String id;private String name;private String description;private List<Course> courses;public Student(String id, String name, String description,List<Course> courses) {super();this.id = id;this.name = name;this.description = description;this.courses = courses;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getDescription() {return description;}public void setDescription(String description) {this.description = description;}public List<Course> getCourses() {return courses;}public void setCourses(List<Course> courses) {this.courses = courses;}@Overridepublic String toString() {return String.format("Student [id=%s, name=%s, description=%s, courses=%s]", id,name, description, courses);}}src/main/java/com/in28minutes/springboot/service/StudentService.java
package com.in28minutes.springboot.service;import java.math.BigInteger;import java.security.SecureRandom;import java.util.ArrayList;import java.util.Arrays;import java.util.List;import org.springframework.stereotype.Component;import com.in28minutes.springboot.model.Course;import com.in28minutes.springboot.model.Student;@Componentpublic class StudentService {private static List<Student> students = new ArrayList<>();static {//Initialize DataCourse course1 = new Course("Course1", "Spring", "10 Steps", Arrays.asList("Learn Maven", "Import Project", "First Example","Second Example"));Course course2 = new Course("Course2", "Spring MVC", "10 Examples",Arrays.asList("Learn Maven", "Import Project", "First Example","Second Example"));Course course3 = new Course("Course3", "Spring Boot", "6K Students",Arrays.asList("Learn Maven", "Learn Spring","Learn Spring MVC", "First Example", "Second Example"));Course course4 = new Course("Course4", "Maven","Most popular maven course on internet!", Arrays.asList("Pom.xml", "Build Life Cycle", "Parent POM","Importing into Eclipse"));Student ranga = new Student("Student1", "Ranga Karanam","Hiker, Programmer and Architect", new ArrayList<>(Arrays.asList(course1, course2, course3, course4)));Student satish = new Student("Student2", "Satish T","Hiker, Programmer and Architect", new ArrayList<>(Arrays.asList(course1, course2, course3, course4)));students.add(ranga);students.add(satish);}public List<Student> retrieveAllStudents() {return students;}public Student retrieveStudent(String studentId) {for (Student student : students) {if (student.getId().equals(studentId)) {return student;}}return null;}public List<Course> retrieveCourses(String studentId) {Student student = retrieveStudent(studentId);if (student == null) {return null;}return student.getCourses();}public Course retrieveCourse(String studentId, String courseId) {Student student = retrieveStudent(studentId);if (student == null) {return null;}for (Course course : student.getCourses()) {if (course.getId().equals(courseId)) {return course;}}return null;}private SecureRandom random = new SecureRandom();public Course addCourse(String studentId, Course course) {Student student = retrieveStudent(studentId);if (student == null) {return null;}String randomId = new BigInteger(130, random).toString(32);course.setId(randomId);student.getCourses().add(course);return course;}}src/main/java/com/in28minutes/springboot/StudentServicesApplication.java
package com.in28minutes.springboot;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class StudentServicesApplication {public static void main(String[] args) {SpringApplication.run(StudentServicesApplication.class, args);}}以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持武林网。