关于OAuth 2.0，请参见下面这两篇文章（墙裂推荐）：

《OAuth 2.0》

《Spring Security OAuth 2.0》

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纸上得来终觉浅，绝知此事要躬行。理论知识了解以后，最终还是要动手实践，不亲自做一遍永远不知道里面有多少坑。本节的重点是用Spring Security实现授权码模式。

1. maven依赖

<?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.cjs.example</groupId><artifactId>cjs-oauth2-code-server</artifactId><version>0.0.1-SNAPSHOT</version><packaging>jar</packaging><name>cjs-oauth2-code-server</name><description></description><parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.0.2.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-security</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-thymeleaf</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.security.oauth</groupId><artifactId>spring-security-oauth2</artifactId><version>2.3.3.RELEASE</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency><dependency><groupId>org.springframework.security</groupId><artifactId>spring-security-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>

2. 配置Security

package com.cjs.example.config;import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.security.config.annotation.authentication.builders.AuthenticationManagerBuilder;
import org.springframework.security.config.annotation.web.builders.HttpSecurity;
import org.springframework.security.config.annotation.web.builders.WebSecurity;
import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
import org.springframework.security.config.annotation.web.configuration.WebSecurityConfigurerAdapter;
import org.springframework.security.core.userdetails.User;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.core.userdetails.UserDetailsService;
import org.springframework.security.crypto.bcrypt.BCryptPasswordEncoder;
import org.springframework.security.crypto.password.PasswordEncoder;
import org.springframework.security.provisioning.InMemoryUserDetailsManager;@Configuration
@EnableWebSecurity
public class WebSecurityConfig extends WebSecurityConfigurerAdapter {@Overrideprotected void configure(AuthenticationManagerBuilder auth) throws Exception {super.configure(auth);
//        auth.inMemoryAuthentication().withUser("zhangsan").password("$2a$10$qsJ/Oy1RmUxFA.YtDT8RJ.Y2kU3U4z0jvd35YmiMOAPpD.nZUIRMC").roles("USER");}@Overridepublic void configure(WebSecurity web) throws Exception {super.configure(web);}@Overrideprotected void configure(HttpSecurity http) throws Exception {super.configure(http);}@Bean@Overrideprotected UserDetailsService userDetailsService() {User.UserBuilder builder = User.builder();UserDetails user = builder.username("zhangsan").password("$2a$10$GStfEJEyoSHiSxnoP3SbD.R8XRowP1QKOdi.N6/iFEwEJWTQqlSba").roles("USER").build();UserDetails admin = builder.username("lisi").password("$2a$10$GStfEJEyoSHiSxnoP3SbD.R8XRowP1QKOdi.N6/iFEwEJWTQqlSba").roles("USER", "ADMIN").build();return new InMemoryUserDetailsManager(user, admin);}@Beanpublic PasswordEncoder passwordEncoder() {return new BCryptPasswordEncoder();}public static void main(String[] args) {BCryptPasswordEncoder bCryptPasswordEncoder = new BCryptPasswordEncoder();System.out.println(bCryptPasswordEncoder.encode("123456"));System.out.println(bCryptPasswordEncoder.encode("12345678"));}
}

3. 配置授权服务器

package com.cjs.example.config;import org.springframework.context.annotation.Configuration;
import org.springframework.security.oauth2.config.annotation.configurers.ClientDetailsServiceConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configuration.AuthorizationServerConfigurerAdapter;
import org.springframework.security.oauth2.config.annotation.web.configuration.EnableAuthorizationServer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerEndpointsConfigurer;
import org.springframework.security.oauth2.config.annotation.web.configurers.AuthorizationServerSecurityConfigurer;@Configuration
@EnableAuthorizationServer
public class AuthorizationServerConfig extends AuthorizationServerConfigurerAdapter {@Overridepublic void configure(AuthorizationServerSecurityConfigurer security) throws Exception {super.configure(security);}@Overridepublic void configure(ClientDetailsServiceConfigurer clients) throws Exception {clients.inMemory().withClient("my-client-1").secret("$2a$10$0jyHr4rGRdQw.X9mrLkVROdQI8.qnWJ1Sl8ly.yzK0bp06aaAkL9W").authorizedGrantTypes("authorization_code", "refresh_token").scopes("all").redirectUris("http://www.baidu.com");}@Overridepublic void configure(AuthorizationServerEndpointsConfigurer endpoints) throws Exception {super.configure(endpoints);}public static void main(String[] args) {System.out.println(new org.apache.tomcat.util.codec.binary.Base64().encodeAsString("my-client-1:12345678".getBytes()));System.out.println(java.util.Base64.getEncoder().encodeToString("my-client-1:12345678".getBytes()));}
}

这里客户端的secret是12345678，存储的是加密后的值

4. 启动类

package com.cjs.example;import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication
public class CjsOauth2CodeServerApplication {public static void main(String[] args) {SpringApplication.run(CjsOauth2CodeServerApplication.class, args);}
}

到目前为止，好像我们就做了两件事情：一、配置用户；二、注册客户端

现在，我们有两个用户（zhangsan和lisi）以及一个已注册的客户端（my-client-1）

接下来，用postman模拟客户端请求获取access_token

5. 协议端点

我们知道，在获取access_token之前需要用户授权，然后返回一个code，最后用code换access_token

在这个过程中涉及到三个服务器端点：授权端点、重定向端点、令牌端点

通过控制台看看启动日志可能会加深理解：

  .   ____          _            __ _ _/\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/  ___)| |_)| | | | | || (_| |  ) ) ) )'  |____| .__|_| |_|_| |_\__, | / / / /=========|_|==============|___/=/_/_/_/:: Spring Boot ::        (v2.0.3.RELEASE)2018-06-26 09:44:09.575  INFO 6528 --- [           main] c.c.e.CjsOauth2CodeServerApplication     : Starting CjsOauth2CodeServerApplication on USER-20170302XK with PID 6528 (E:\cjsworkspace\cjs-oauth2-example\cjs-oauth2-code-server\target\classes started by Administrator in E:\cjsworkspace\cjs-oauth2-example\cjs-oauth2-code-server)
2018-06-26 09:44:09.597  INFO 6528 --- [           main] c.c.e.CjsOauth2CodeServerApplication     : No active profile set, falling back to default profiles: default
2018-06-26 09:44:09.762  INFO 6528 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@22635ba0: startup date [Tue Jun 26 09:44:09 CST 2018]; root of context hierarchy
2018-06-26 09:44:12.931  INFO 6528 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2018-06-26 09:44:12.997  INFO 6528 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-06-26 09:44:12.998  INFO 6528 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.31
2018-06-26 09:44:13.200  INFO 6528 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-06-26 09:44:13.200  INFO 6528 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 3448 ms
2018-06-26 09:44:13.379  INFO 6528 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-06-26 09:44:13.379  INFO 6528 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-06-26 09:44:13.379  INFO 6528 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-06-26 09:44:13.379  INFO 6528 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-06-26 09:44:13.379  INFO 6528 --- [ost-startStop-1] .s.DelegatingFilterProxyRegistrationBean : Mapping filter: 'springSecurityFilterChain' to: [/*]
2018-06-26 09:44:13.380  INFO 6528 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
2018-06-26 09:44:13.529  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/authorize]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.security.oauth2.provider.endpoint.AuthorizationEndpoint.authorize(java.util.Map<java.lang.String, java.lang.Object>,java.util.Map<java.lang.String, java.lang.String>,org.springframework.web.bind.support.SessionStatus,java.security.Principal)
2018-06-26 09:44:13.530  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/authorize],methods=[POST],params=[user_oauth_approval]}" onto public org.springframework.web.servlet.View org.springframework.security.oauth2.provider.endpoint.AuthorizationEndpoint.approveOrDeny(java.util.Map<java.lang.String, java.lang.String>,java.util.Map<java.lang.String, ?>,org.springframework.web.bind.support.SessionStatus,java.security.Principal)
2018-06-26 09:44:13.530  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/token],methods=[POST]}" onto public org.springframework.http.ResponseEntity<org.springframework.security.oauth2.common.OAuth2AccessToken> org.springframework.security.oauth2.provider.endpoint.TokenEndpoint.postAccessToken(java.security.Principal,java.util.Map<java.lang.String, java.lang.String>) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-06-26 09:44:13.531  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/token],methods=[GET]}" onto public org.springframework.http.ResponseEntity<org.springframework.security.oauth2.common.OAuth2AccessToken> org.springframework.security.oauth2.provider.endpoint.TokenEndpoint.getAccessToken(java.security.Principal,java.util.Map<java.lang.String, java.lang.String>) throws org.springframework.web.HttpRequestMethodNotSupportedException
2018-06-26 09:44:13.531  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/check_token]}" onto public java.util.Map<java.lang.String, ?> org.springframework.security.oauth2.provider.endpoint.CheckTokenEndpoint.checkToken(java.lang.String)
2018-06-26 09:44:13.531  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/confirm_access]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.security.oauth2.provider.endpoint.WhitelabelApprovalEndpoint.getAccessConfirmation(java.util.Map<java.lang.String, java.lang.Object>,javax.servlet.http.HttpServletRequest) throws java.lang.Exception
2018-06-26 09:44:13.531  INFO 6528 --- [           main] .s.o.p.e.FrameworkEndpointHandlerMapping : Mapped "{[/oauth/error]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.security.oauth2.provider.endpoint.WhitelabelErrorEndpoint.handleError(javax.servlet.http.HttpServletRequest)
2018-06-26 09:44:13.760  INFO 6528 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-26 09:44:14.019  INFO 6528 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@22635ba0: startup date [Tue Jun 26 09:44:09 CST 2018]; root of context hierarchy
2018-06-26 09:44:14.049  INFO 6528 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-06-26 09:44:14.049  INFO 6528 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-06-26 09:44:14.062  INFO 6528 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-26 09:44:14.063  INFO 6528 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-26 09:44:14.103  WARN 6528 --- [           main] ion$DefaultTemplateResolverConfiguration : Cannot find template location: classpath:/templates/ (please add some templates or check your Thymeleaf configuration)
2018-06-26 09:44:14.865  INFO 6528 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-06-26 09:44:14.901  INFO 6528 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2018-06-26 09:44:14.904  INFO 6528 --- [           main] c.c.e.CjsOauth2CodeServerApplication     : Started CjsOauth2CodeServerApplication in 6.298 seconds (JVM running for 8.287)

5.1. 授权端点

请求

参数名称	描述
response_type	必填。将其值设置为code表示如果成功的话将收到一个授权码。
client_id	必填。客户端标识。
redirect_uri	可选。重定向URI虽然不是必须的，但是你的服务应该会需要它。而且，这个URL必须和授权服务端注册的redirect_id一致。
scope	可选。请求可能会有一个或多个scope值。授权服务器会把客户端请求的范围(scope)展示给用户看。
state	推荐。state参数用于应用存储特定的请求数据的可以防止CSRF攻击。授权服务器必须原封不动地将这个值返回给应用。

例如：

http://localhost:8080/oauth/authorize?response_type=code&client_id=my-client-1&redirect_uri=http://www.baidu.com&scope=all

响应

参数名称	描述
code	授权码，稍后用此授权码交换访问令牌
state	请求时带的state参数

例如：

https://www.baidu.com/?code=7Zudn6

5.2. 令牌端点

请求

参数名称	描述
grant_type	必填。参数值必须是"authorization_code"
code	必填。之前收到的授权码
redirect_uri	可能是必填的。如果授权请求的时候有redirect_uri，那么token请求的时候也必须带上这个参数，二者的值必须是一样的。
client_id	客户端标识，如果没有其它的客户端认证存在的话这个参数是必须的。

关于客户端认证补充一点

授权服务器可以通过HTTP Basic Auth方式对客户端进行认证，也可以通过在请求中加一个client_secret参数来对客户端进行认证。

不建议将客户端的secret直接作为参数放到client_secret中，而且这种方式下client_id和client_secret都是必填参数。

特别注意，用户（资源所有者）的用户名和密码跟客户端的用户名和密码（client_id、client_secret）不是一套，它们是两个东西。

那么，通过HTTP Basic Auth如何对客户端进行认证呢？客户端需要怎样传参呢？

需要在请求header中设置Authorization，它的值是Basic + 空格 + Base64加密后的client_id:secret

至于为什么，那是协议要求的，具体可以参考https://tools.ietf.org/html/rfc2617#page-5，格式如下：

例如：

POST /oauth/token HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Authorization: Basic bXktY2xpZW50LTE6MTIzNDU2Nzg=
cache-control: no-cache
Postman-Token: baf729b9-f030-41c1-b6fb-d740b0c5c573
User-Agent: PostmanRuntime/7.1.1
Accept: */*
Host: localhost:8080
cookie: JSESSIONID=45EAF00C9829B9F569579DB08533D850; UISESSION=2A65FF6FC8C6BE415DE3C043E3EDAAA4
accept-encoding: gzip, deflate
content-length: 103
Connection: keep-alivegrant_type=authorization_code&code=7Zudn6&redirect_uri=http%3A%2F%2Fwww.baidu.com&client_id=my-client-1

6. 客户端请求

直接在浏览器中输入以下地址，然后会跳到登录授权页面

http://localhost:8080/oauth/authorize?response_type=code&client_id=my-client-1&redirect_uri=http://www.baidu.com&scope=all

上面这两个页面都是默认自带的

授权成功以后重定向

有了授权码以后就可以换取access_token了

这个请求中唯一需要注意的一个参数就是Authorization，这是用于认证客户端的，本例中它是这样算出来的

public static void main(String[] args) {System.out.println(new org.apache.tomcat.util.codec.binary.Base64().encodeAsString("my-client-1:12345678".getBytes()));System.out.println(java.util.Base64.getEncoder().encodeToString("my-client-1:12345678".getBytes()));
}

所以，最终是Basic bXktY2xpZW50LTE6MTIzNDU2Nzg=

到此为止，我们只是获得了access_token，下一节将讲解如何配置资源服务器，以及客户端访问受保护的资源。

另外，本例中关于令牌的存储，以及客户端注册都是在内存中，实际生产过程中肯定是要存储到数据库中的，这一部分以后有时间再写吧！