如何快速構建基於Spring4.0的Rest API(攻略)
這是關於使用Spring MVC創建Web API的另一個教程。這並不是一個非常精細的教程,而僅僅是一個演習(攻略)。本教程旨在創建一個提供服務器端API的應用,並且使用Mongo作爲它的數據庫,使用Spring Security作爲安全框架。
準備開始——POM
由於我是一個maven腦殘粉,所以這個項目還是基於maven的。現在Spring 4.0 RC2已經發布了,所以我決定使用最新的依賴管理工具。本文使用的pom.xml如下:使用這個配置創建Spring MVC應用確實非常簡單。這裏面比較新鮮的東西就是dependencyManagement 元素。詳解猛戳這兒:http://spring.io/blog/2013/12/03/spring-framework-4-0-rc2-available
配置
這個應用可以使用JavaConfig完成配置。我把它切分爲下面幾個部分:
ServicesConfig(服務配置)
無需掃描組件,配置真的非常簡單:
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@Configuration public
class
ServicesConfig { @Autowired private
AccountRepository accountRepository; @Bean public
UserService userService() { return
new
UserService(accountRepository); } @Bean public
PasswordEncoder passwordEncoder() { return
NoOpPasswordEncoder.getInstance(); } } |
PersistenceConfig(持久層配置)
我們想要一個配置了所有可用倉庫的MONGODB配置。在這個簡單的應用中我們只用了一個倉庫,所以配置也非常的簡單:
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@Configuration class
PersistenceConfig { @Bean public
AccountRepository accountRepository() throws
UnknownHostException { return
new
MongoAccountRepository(mongoTemplate()); } @Bean public
MongoDbFactory mongoDbFactory() throws
UnknownHostException { return
new
SimpleMongoDbFactory( new
Mongo(), "r" ); } @Bean public
MongoTemplate mongoTemplate() throws
UnknownHostException { MongoTemplate
template = new
MongoTemplate(mongoDbFactory(), mongoConverter()); return
template; } @Bean public
MongoTypeMapper mongoTypeMapper() { return
new
DefaultMongoTypeMapper( null ); } @Bean public
MongoMappingContext mongoMappingContext() { return
new
MongoMappingContext(); } @Bean public
MappingMongoConverter mongoConverter() throws
UnknownHostException { MappingMongoConverter
converter = new
MappingMongoConverter(mongoDbFactory(), mongoMappingContext()); converter.setTypeMapper(mongoTypeMapper()); return
converter; } } |
SecurityConfig(安全配置)
理論上,Spring Security 3.2完全可以使用JavaConfig。但對於我這也僅僅是一個理論,所以這裏還是選擇xml配置的方式:
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@Configuration @ImportResource ( "classpath:spring-security-context.xml" ) public
class
SecurityConfig {} |
使用這個xml就讓API能使用基本的安全機制了。
WebAppInitializer(初始化)
我們不想使用web.xml,所以使用下面的代碼配置整個應用:
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@Order ( 2 ) public
class
WebAppInitializer extends
AbstractAnnotationConfigDispatcherServletInitializer { @Override protected
String[] getServletMappings() { return
new
String[]{ "/" }; } @Override protected
Class[] getRootConfigClasses() { return
new
Class[] {ServicesConfig. class ,
PersistenceConfig. class ,
SecurityConfig. class }; } @Override protected
Class[] getServletConfigClasses() { return
new
Class[] {WebMvcConfig. class }; } @Override protected
Filter[] getServletFilters() { CharacterEncodingFilter
characterEncodingFilter = new
CharacterEncodingFilter(); characterEncodingFilter.setEncoding( "UTF-8" ); characterEncodingFilter.setForceEncoding( true ); return
new
Filter[] {characterEncodingFilter}; } @Override protected
void
customizeRegistration(ServletRegistration.Dynamic registration) { registration.setInitParameter( "spring.profiles.active" ,
"default" ); } } |
WebAppSecurityInitializer (安全配置初始化)
相對於Spring3,可以使用下面這種更加新穎的特性來完成配置:
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@Order ( 1 ) public
class
WebAppSecurityInitializer extends
AbstractSecurityWebApplicationInitializer {} |
WebMvcConfig (Mvc配置)
調度控制器配置。這個也非常簡單,僅僅包含了構建一個簡單API的最重要配置:
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@Configuration @ComponentScan (basePackages
= { "pl.codeleak.r"
}, includeFilters = { @Filter (value
= Controller. class )}) public
class
WebMvcConfig extends
WebMvcConfigurationSupport { private
static
final
String MESSAGE_SOURCE = "/WEB-INF/i18n/messages" ; @Override public
RequestMappingHandlerMapping requestMappingHandlerMapping() { RequestMappingHandlerMapping
requestMappingHandlerMapping = super .requestMappingHandlerMapping(); requestMappingHandlerMapping.setUseSuffixPatternMatch( false ); requestMappingHandlerMapping.setUseTrailingSlashMatch( false ); return
requestMappingHandlerMapping; } @Bean (name
= "messageSource" ) public
MessageSource messageSource() { ReloadableResourceBundleMessageSource
messageSource = new
ReloadableResourceBundleMessageSource(); messageSource.setBasename(MESSAGE_SOURCE); messageSource.setCacheSeconds( 5 ); return
messageSource; } @Override public
Validator getValidator() { LocalValidatorFactoryBean
validator = new
LocalValidatorFactoryBean(); validator.setValidationMessageSource(messageSource()); return
validator; } @Override public
void
configureDefaultServletHandling(DefaultServletHandlerConfigurer configurer) { configurer.enable(); } } |
這就是需要的配置,非常簡單吧!
IndexController (INDEX控制器)
爲了驗證這個配置是正確的,我創建了一個IndexController。功能非常簡單,只是簡單地返回“Hello World”,示例代碼如下:
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@Controller @RequestMapping ( "/" ) public
class
IndexController { @RequestMapping @ResponseBody public
String index() { return
"This is an API endpoint." ; } } |
如果運行一下這個應用,就能夠在瀏覽器中看到返回的“Hello World”文本。
構建API
UserService
爲了完成Spring安全框架配置,還需要完成另一個部分:實現之前創建的UserService。
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public
class
UserService implements
UserDetailsService { private
AccountRepository accountRepository; public
UserService(AccountRepository accountRepository) { this .accountRepository
= accountRepository; } @Override public
UserDetails loadUserByUsername(String username) throws
UsernameNotFoundException { Account
account = accountRepository.findByEmail(username); if (account
== null )
{ throw
new
UsernameNotFoundException( "user
not found" ); } return
createUser(account); } public
void
signin(Account account) { SecurityContextHolder.getContext().setAuthentication(authenticate(account)); } private
Authentication authenticate(Account account) { return
new
UsernamePasswordAuthenticationToken(createUser(account), null ,
Collections.singleton(createAuthority(account))); } private
User createUser(Account account) { return
new
User(account.getEmail(), account.getPassword(), Collections.singleton(createAuthority(account))); } private
GrantedAuthority createAuthority(Account account) { return
new
SimpleGrantedAuthority(account.getRole()); } } |
構建一個API節點需要處理三個方法:獲取當前登陸用戶、獲取所有用戶(可能不是太安全)、創建一個新賬戶。那麼我們就按照這個步驟來進行吧。
Account
Account 將會是我們的第一個Mongo文檔。同樣也是非常簡單:
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@SuppressWarnings ( "serial" ) @Document public
class
Account implements
java.io.Serializable { @Id private
String objectId; @Email @Indexed (unique
= true ) private
String email; @JsonIgnore @NotBlank private
String password; private
String role = "ROLE_USER" ; private
Account() { } public
Account(String email, String password, String role) { this .email
= email; this .password
= password; this .role
= role; } //
getters and setters } |
Repository
先創建一個接口:
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public
interface
AccountRepository { Account
save(Account account); List
findAll(); Account
findByEmail(String email); } |
接下來創建它的Mongo實現:
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public
class
MongoAccountRepository implements
AccountRepository { private
MongoTemplate mongoTemplate; public
MongoAccountRepository(MongoTemplate mongoTemplate) { this .mongoTemplate
= mongoTemplate; } @Override public
Account save(Account account) { mongoTemplate.save(account); return
account; } @Override public
List findAll() { return
mongoTemplate.findAll(Account. class ); } @Override public
Account findByEmail(String email) { return
mongoTemplate.findOne(Query.query(Criteria.where( "email" ).is(email)),
Account. class ); } } |
API控制器
功能快要完成了。我們需要將內容提供給用戶,所以需要創建自己的節點:
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@Controller @RequestMapping ( "api/account" ) class
AccountController { private
AccountRepository accountRepository; @Autowired public
AccountController(AccountRepository accountRepository) { this .accountRepository
= accountRepository; } @RequestMapping (value
= "current" ,
method = RequestMethod.GET) @ResponseStatus (value
= HttpStatus.OK) @ResponseBody @PreAuthorize (value
= "isAuthenticated()" ) public
Account current(Principal principal) { Assert.notNull(principal); return
accountRepository.findByEmail(principal.getName()); } @RequestMapping (method
= RequestMethod.GET) @ResponseStatus (value
= HttpStatus.OK) @ResponseBody @PreAuthorize (value
= "isAuthenticated()" ) public
Accounts list() { List
accounts = accountRepository.findAll(); return
new
Accounts(accounts); } @RequestMapping (method
= RequestMethod.POST) @ResponseStatus (value
= HttpStatus.CREATED) @ResponseBody @PreAuthorize (value
= "permitAll()" ) public
Account create( @Valid
Account account) { accountRepository.save(account); return
account; } private
class
Accounts extends
ArrayList { public
Accounts(List accounts) { super (accounts); } } } |
我希望你能明白:因爲需要直接連接數據庫,所以沒有對密碼進行編碼。如果你比較在意這些小細節,那麼可以稍後修改。目前這種方式是OK的。
完成
最後我考慮到還需要一個錯誤處理器,這樣用戶就可以看到JSON格式的錯誤信息而不是HTML。使用Spring Mvc以及@ControllerAdvice很容易實現這一點:
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@ControllerAdvice public
class
ErrorHandler { @ExceptionHandler (value
= Exception. class ) @ResponseStatus (HttpStatus.BAD_REQUEST) @ResponseBody public
ErrorResponse errorResponse(Exception exception) { return
new
ErrorResponse(exception.getMessage()); } } public
class
ErrorResponse { private
String message; public
ErrorResponse(String message) { this .message
= message; } public
String getMessage() { return
message; } } |
如果你想了解關於Spring4 中@ControllerAdvice的用法,請點擊以下鏈接。
測試一下這個app
作爲一個單元測試極客,本來應該先創建一個單元測試。但是……這次哥想用用新的工具:Postman(Chrome 插件),所以請往下看我是怎麼做的:
獲取所有account(非授權)
提交account(無需授權)
獲取所有account(已授權)
獲取當前account(已授權)
結束語
以上就是所有內容,希望你能像我一樣喜歡這種創建項目的方式。創建這個項目以及寫這篇文章總共花了我大概三個鐘頭。其中絕大多數時間是配置安全框架(我希望它在Java中能夠更加徹底),以及編寫這篇攻略。
原文鏈接: javacodegeeks 翻譯: ImportNew.com - 鄔柏
譯文鏈接: http://www.importnew.com/7903.html
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