Spring Boot 建立RESTFul服務
本文測試並總結Spring官網構建RESTful風格的HTTP服務。
官方地址:https://spring.io/guides/tutorials/bookmarks/
demo倉庫地址:https://github.com/spring-guides/tut-rest
RESTful風格的http服務包含以下特徵:
1、每一個URI代表1種資源;
2、客戶端使用GET、POST、PUT、DELETE4個表示操作方式的動詞對服務端資源進行操作:GET用來獲取資源,POST用來新建資源(也可以用於更新資源),PUT
3、通過操作資源的表現形式來操作資源;
4、資源的表現形式是XML或者HTML;
5、客戶端與服務端之間的互動在請求之間是無狀態的,從客戶端到服務端的每個請求都必須包含理解請求所必需的資訊。
英文描述,RESTful不是標準,只是架構上的一種方法,一種樣式和一組約束。
What’s important to realize is that REST, however ubiquitous, is not a standard, per se, but an approach, a style, a set of constraints on your architecture that can help you build web-scale systems. |
本文結論:
首先:
GET,獲取資源,/employees表示獲取列表資源,/employees/{id}表示獲取單個物件資源。
POST,新增,/employees,body為json物件,表示新增。
PUT,更新,/employees/{id},body為json物件,表示更新。
DELETE,刪除, /employees/{id},表示更新。
其次:
返回資料為列表,則每個物件資源附加自己的資源連結、列表資源連結以及可操作性連結。
{ "_embedded": { "orderList": [ { "id": 3,"description": "MacBook Pro", "status": "COMPLETED", "_links": { "self": { "href": "http://localhost:8080/orders/3" }, "orders": { "href": "http://localhost:8080/orders" } } }, { "id": 4, "description": "iPhone", "status": "IN_PROGRESS", "_links": { "self": { "href": "http://localhost:8080/orders/4" }, "orders": { "href": "http://localhost:8080/orders" }, "cancel": { "href": "http://localhost:8080/orders/4/cancel" }, "complete": { "href": "http://localhost:8080/orders/4/complete" } } } ] }, "_links": { "self": { "href": "http://localhost:8080/orders" } } }
普通的http服務
可以沒有application.properties配置檔案
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 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.htkm.demo</groupId> <artifactId>demo-restful</artifactId> <version>0.0.1-SNAPSHOT</version> <name>demo-restful</name> <description>Demo project for Spring Boot</description> <properties> <java.version>1.8</java.version> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <spring-boot.version>2.3.0.RELEASE</spring-boot.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-hateoas</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId> </dependency> <dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> </dependency> <dependency> <groupId>com.h2database</groupId> <artifactId>h2</artifactId> <scope>runtime</scope> </dependency> </dependencies> <dependencyManagement> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-dependencies</artifactId> <version>${spring-boot.version}</version> <type>pom</type> <scope>import</scope> </dependency> </dependencies> </dependencyManagement> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.8</source> <target>1.8</target> <encoding>UTF-8</encoding> </configuration> </plugin> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
實體類
@Data @Entity public class Employee { @Id @GeneratedValue private Long id; private String name; private String role; public Employee() {} public Employee(String name, String role) { this.name = name; this.role = role; } }
測試資料庫,使用H2記憶體資料庫
@Configuration @Slf4j public class LoadDatabase { @Bean CommandLineRunner initDatabase(EmployeeRepository repository) { return args -> { log.info("Preloading " + repository.save(new Employee("Bilbo Baggins", "burglar"))); log.info("Preloading " + repository.save(new Employee("Frodo Baggins", "thief"))); }; } }
Dao
public interface EmployeeRepository extends JpaRepository<Employee, Long> {}
控制器
@RestController public class EmployeeController { @Autowired private EmployeeRepository repository; @GetMapping("/employees") List<Employee> all() { return repository.findAll(); } @PostMapping("/employees") Employee newEmployee(@RequestBody Employee newEmployee) { return repository.save(newEmployee); } @GetMapping("/employees/{id}") Employee one(@PathVariable Long id) { return repository.findById(id) .orElseThrow(() -> new EmployeeNotFoundException(id)); } @PutMapping("/employees/{id}") Employee replaceEmployee(@RequestBody Employee newEmployee, @PathVariable Long id) { return repository.findById(id) .map(employee -> { employee.setName(newEmployee.getName()); employee.setRole(newEmployee.getRole()); return repository.save(employee); }) .orElseGet(() -> { newEmployee.setId(id); return repository.save(newEmployee); }); } @DeleteMapping("/employees/{id}") void deleteEmployee(@PathVariable Long id) { repository.deleteById(id); } }
自定義異常
public class EmployeeNotFoundException extends RuntimeException { public EmployeeNotFoundException(Long id) { super("Could not find employee " + id); } }
異常處理器
@ControllerAdvice public class EmployeeNotFoundAdvice { @ResponseBody @ExceptionHandler(EmployeeNotFoundException.class) @ResponseStatus(HttpStatus.NOT_FOUND) String employeeNotFoundHandler(EmployeeNotFoundException ex) { return ex.getMessage(); } }
測試執行,使用postman或者curl工具測試
GET http://localhost:8080/employees |
[ { "id":1, "name":"BilboBaggins", "role":"burglar" }, { "id":2, "name":"FrodoBaggins", "role":"thief" } ] |
GET http://localhost:8080/employees/1 |
{ "id":1, "name":"BilboBaggins", "role":"burglar" } |
DELETE http://localhost:8080/employees/1 |
刪除 |
restful的http服務
pom.xml,增加hateoas依賴
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-hateoas</artifactId> </dependency>
控制器更改,在原來的返回json基礎之上附加操作連結,紅色加粗部分可以重構簡化,在下一章節。
@GetMapping("/employees") CollectionModel<EntityModel<Employee>> all() { List<EntityModel<Employee>> employees = repository.findAll().stream() .map(employee -> EntityModel.of(employee, linkTo(methodOn(EmployeeController.class).one(employee.getId())).withSelfRel(), // 附加自身連結 linkTo(methodOn(EmployeeController.class).all()).withRel("employees"))) // 附加all操作連結 .collect(Collectors.toList()); return CollectionModel.of(employees, linkTo(methodOn(EmployeeController.class).all()).withSelfRel()); // 附加自身連結 } @GetMapping("/employees/{id}") EntityModel<Employee> one(@PathVariable Long id) { Employee employee = repository.findById(id) // .orElseThrow(() -> new EmployeeNotFoundException(id)); return EntityModel.of(employee, linkTo(methodOn(EmployeeController.class).one(id)).withSelfRel(), // 附加自身連結 linkTo(methodOn(EmployeeController.class).all()).withRel("employees")); // 附加all操作連結 }
測試執行
GET http://localhost:8080/employees |
{ "_embedded":{ "employeeList":[ { "id":1, "name":"BilboBaggins", "role":"burglar", "_links":{ "self":{ "href":"http://localhost:8080/employees/1" }, "employees":{ "href":"http://localhost:8080/employees" } } }, { "id":2, "name":"FrodoBaggins", "role":"thief", "_links":{ "self":{ "href":"http://localhost:8080/employees/2" }, "employees":{ "href":"http://localhost:8080/employees" } } } ] }, "_links":{ "self":{ "href":"http://localhost:8080/employees" } } } |
GET http://localhost:8080/employees/1 |
{ "id":1, "name":"BilboBaggins", "role":"burglar", "_links":{ "self":{ "href":"http://localhost:8080/employees/1" }, "employees":{ "href":"http://localhost:8080/employees" } } } |
擴充套件的restful服務
擴充套件實體,將name拆分為fristname和lastname,同時通過增加虛擬的get/set保留name屬性
@Data @Entity public class Employee { @Id @GeneratedValue private Long id; private String firstName; private String lastName; private String role; public Employee() {} public Employee(String firstName, String lastName, String role) { this.firstName = firstName; this.lastName = lastName; this.role = role; } public String getName() { return this.firstName + " " + this.lastName; } public void setName(String name) { String[] parts = name.split(" "); this.firstName = parts[0]; this.lastName = parts[1]; } }
重構簡化程式碼,增加物件包裝處理類
@Component class EmployeeModelAssembler implements RepresentationModelAssembler<Employee, EntityModel<Employee>> { @Override public EntityModel<Employee> toModel(Employee employee) { return EntityModel.of(employee, linkTo(methodOn(EmployeeController.class).one(employee.getId())).withSelfRel(), linkTo(methodOn(EmployeeController.class).all()).withRel("employees")); } }
控制器更改
@RestController public class EmployeeController { @Autowired private EmployeeRepository repository; @Autowired private EmployeeModelAssembler assembler; @GetMapping("/employees") CollectionModel<EntityModel<Employee>> all() { List<EntityModel<Employee>> employees = repository.findAll().stream() .map(assembler::toModel) // 包裝物件 .collect(Collectors.toList()); return CollectionModel.of(employees, linkTo(methodOn(EmployeeController.class).all()).withSelfRel()); // 附加自身連結 } @PostMapping("/employees") ResponseEntity<?> newEmployee(@RequestBody Employee newEmployee) { EntityModel<Employee> entityModel = assembler.toModel(repository.save(newEmployee)); return ResponseEntity .created(entityModel.getRequiredLink(IanaLinkRelations.SELF).toUri()) .body(entityModel); // 返回狀態碼201,增加Location頭 http://localhost:8080/employees/3 } @GetMapping("/employees/{id}") EntityModel<Employee> one(@PathVariable Long id) { Employee employee = repository.findById(id) // .orElseThrow(() -> new EmployeeNotFoundException(id)); return assembler.toModel(employee); // 包裝物件 } @PutMapping("/employees/{id}") ResponseEntity<?> replaceEmployee(@RequestBody Employee newEmployee, @PathVariable Long id) { Employee updatedEmployee = repository.findById(id) // .map(employee -> { employee.setName(newEmployee.getName()); employee.setRole(newEmployee.getRole()); return repository.save(employee); }) // .orElseGet(() -> { newEmployee.setId(id); return repository.save(newEmployee); }); EntityModel<Employee> entityModel = assembler.toModel(updatedEmployee); return ResponseEntity .created(entityModel.getRequiredLink(IanaLinkRelations.SELF).toUri()) .body(entityModel); // 返回狀態碼201,增加Location頭 http://localhost:8080/employees/3 } @DeleteMapping("/employees/{id}") ResponseEntity<?> deleteEmployee(@PathVariable Long id) { repository.deleteById(id); return ResponseEntity.noContent().build();// 返回狀態碼204 } }
curl測試執行
curl -v -X POST localhost:8080/employees -H 'Content-Type:application/json' -d '{"name": "Samwise Gamgee", "role": "gardener"}' |
請求相應狀態為201,包含Location響應頭 > POST /employees HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
> Content-Type:application/json
> Content-Length: 46
>
< Location: http://localhost:8080/employees/3 < Content-Type: application/hal+json;charset=UTF-8 < Transfer-Encoding: chunked
< Date: Fri, 10 Aug 2018 19:44:43 GMT
<
{
"id": 3,
"firstName": "Samwise",
"lastName": "Gamgee",
"role": "gardener",
"name": "Samwise Gamgee",
"_links": {
"self": {
"href": "http://localhost:8080/employees/3"
},
"employees": {
"href": "http://localhost:8080/employees"
}
}
}
|
curl -v -X PUT localhost:8080/employees/3 -H 'Content-Type:application/json' -d '{"name": "Samwise Gamgee", "role": "ring bearer"}' |
> PUT /employees/3 HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.54.0
> Accept: */*
> Content-Type:application/json
> Content-Length: 49
>
< HTTP/1.1 201 < Location: http://localhost:8080/employees/3 < Content-Type: application/hal+json;charset=UTF-8
< Transfer-Encoding: chunked
< Date: Fri, 10 Aug 2018 19:52:56 GMT
{
"id": 3,
"firstName": "Samwise",
"lastName": "Gamgee",
"role": "ring bearer",
"name": "Samwise Gamgee",
"_links": {
"self": {
"href": "http://localhost:8080/employees/3"
},
"employees": {
"href": "http://localhost:8080/employees"
}
}
}
|
curl -v -X DELETE localhost:8080/employees/1 |
> DELETE /employees/1 HTTP/1.1 > Host: localhost:8080 > User-Agent: curl/7.54.0 > Accept: */* > < HTTP/1.1 204 < Date: Fri, 10 Aug 2018 21:30:26 GMT |
附加可操作連結的restful服務
訂單實體轉換器,如果訂單狀態為可執行的連結則附加取消和完成連結
@Component public class OrderModelAssembler implements RepresentationModelAssembler<Order, EntityModel<Order>> { @Override public EntityModel<Order> toModel(Order order) { // Unconditional links to single-item resource and aggregate root EntityModel<Order> orderModel = EntityModel.of(order, linkTo(methodOn(OrderController.class).one(order.getId())).withSelfRel(), linkTo(methodOn(OrderController.class).all()).withRel("orders")); // Conditional links based on state of the order if (order.getStatus() == Status.IN_PROGRESS) { orderModel.add(linkTo(methodOn(OrderController.class).cancel(order.getId())).withRel("cancel")); // 附加cancel連結 orderModel.add(linkTo(methodOn(OrderController.class).complete(order.getId())).withRel("complete")); // 附加complete連結 } return orderModel; } }
控制器中取消和完成操作
@DeleteMapping("/orders/{id}/cancel") ResponseEntity<?> cancel(@PathVariable Long id) { Order order = orderRepository.findById(id) .orElseThrow(() -> new OrderNotFoundException(id)); if (order.getStatus() == Status.IN_PROGRESS) { order.setStatus(Status.CANCELLED); return ResponseEntity.ok(assembler.toModel(orderRepository.save(order))); } return ResponseEntity .status(HttpStatus.METHOD_NOT_ALLOWED) .header(HttpHeaders.CONTENT_TYPE, MediaTypes.HTTP_PROBLEM_DETAILS_JSON_VALUE) .body(Problem.create() .withTitle("Method not allowed") .withDetail("You can't cancel an order that is in the " + order.getStatus() + " status")); } @PutMapping("/orders/{id}/complete") ResponseEntity<?> complete(@PathVariable Long id) { Order order = orderRepository.findById(id) .orElseThrow(() -> new OrderNotFoundException(id)); if (order.getStatus() == Status.IN_PROGRESS) { order.setStatus(Status.COMPLETED); return ResponseEntity.ok(assembler.toModel(orderRepository.save(order))); } return ResponseEntity .status(HttpStatus.METHOD_NOT_ALLOWED) .header(HttpHeaders.CONTENT_TYPE, MediaTypes.HTTP_PROBLEM_DETAILS_JSON_VALUE) .body(Problem.create() .withTitle("Method not allowed") .withDetail("You can't complete an order that is in the " + order.getStatus() + " status")); }
PostMan測試執行
GET http://localhost:8080 |
{ "_links":{ "employees":{ "href":"http://localhost:8080/employees" }, "orders":{ "href":"http://localhost:8080/orders" } } } |
GET http://localhost:8080/orders |
{ "_embedded":{ "orderList":[ { "id":3, "description":"MacBookPro", "status":"COMPLETED", "_links":{ "self":{ "href":"http://localhost:8080/orders/3" }, "orders":{ "href":"http://localhost:8080/orders" } } }, { "id":4, "description":"iPhone", "status":"IN_PROGRESS", "_links":{ "self":{ "href":"http://localhost:8080/orders/4" }, "orders":{ "href":"http://localhost:8080/orders" }, "cancel":{ "href":"http://localhost:8080/orders/4/cancel" }, "complete":{ "href":"http://localhost:8080/orders/4/complete" } } } ] }, "_links":{ "self":{ "href":"http://localhost:8080/orders" } } } |
DELETE http://localhost:8080/orders/3/cancel |
{ "title":"Methodnotallowed", "detail":"Youcan'tcancelanorderthatisintheCOMPLETEDstatus" } |
DELETE http://localhost:8080/orders/4/cancel |
{ "id":4, "description":"iPhone", "status":"CANCELLED", "_links":{ "self":{ "href":"http://localhost:8080/orders/4" }, "orders":{ "href":"http://localhost:8080/orders" } } } |
POST localhost:8080/orders Content-Type:application/json {"name": "Samwise Gamgee", "role": "gardener"}' |
{ "id":5, "description":"新的訂單", "status":"IN_PROGRESS", "_links":{ "self":{ "href":"http://localhost:8080/orders/5" }, "orders":{ "href":"http://localhost:8080/orders" }, "cancel":{ "href":"http://localhost:8080/orders/5/cancel" }, "complete":{ "href":"http://localhost:8080/orders/5/complete" } } } |
@Data |
測試資料庫,使用H2記憶體資料庫