user_session_management.png

服务器端需要对客户端发起访问的进行合法性校验：

• 证明你是你
• 鉴权(本文不涉及此内容)

分配 UserAccessToken 流程

+----------+     +-----------------+
|   auth   +---->+   accessToken   |
+----------+     +-----------------+

用户鉴权之后 Server 为用户分配一个访问令牌，后续所有请求 Header中 均携带此令牌供服务器校验。

校验

服务器来承认这个令牌（AccessToken）由它颁发的并且有效。

1. 令牌生成时服务器存储 userId/accessToken/exprieIn
2. 令牌校验时服务器查询存储中是否包含此记录且没过期

存储

服务器内存(分布式内存框架)/传统RDMS/NoSQL(Redis/Memcached)

DynamoDB

• 存储大
• 延迟低
• 扩展快

DynamoDBUserAccessToken.java

@DynamoDBTable(tableName = "user_access_token")
public class DynamoDBUserAccessToken {

    private Long uid;
    private String accessToken;
    private Long expiresIn;
    private String refreshToken;
    private Date refreshTime = new Date();
    private Date createTime = new Date();

    public DynamoDBUserAccessToken() {
    }

    public DynamoDBUserAccessToken(Long uid) {
        super();
        this.uid = uid;
    }

    @DynamoDBHashKey(attributeName = "uid")
    public Long getUid() {
        return uid;
    }

    @DynamoDBAttribute(attributeName = "access_token")
    public String getAccessToken() {
        return accessToken;
    }

    @DynamoDBAttribute(attributeName = "expires_in")
    public Long getExpiresIn() {
        return expiresIn;
    }

    @DynamoDBAttribute(attributeName = "refresh_token")
    public String getRefreshToken() {
        return refreshToken;
    }

    @DynamoDBAttribute(attributeName = "refresh_time")
    public Date getRefreshTime() {
        return refreshTime;
    }

    @DynamoDBAttribute(attributeName = "create_time")
    public Date getCreateTime() {
        return createTime;
    }
// .. 省略 setter 方法
}

DynamoDBConfig.java

@Configuration
public class DynamoDBConfig {

    @Bean
    AmazonDynamoDB amazonDynamoDB() {
        return AmazonDynamoDBClientBuilder
                .standard()
                .withRegion(Regions.US_WEST_2)
                .withCredentials(new PropertiesFileCredentialsProvider("/data/aws-credentials/clipchat-dev.properties"))
                .build();
    }

    @Bean
    DynamoDBMapper dynamoDBMapper() {
        return new DynamoDBMapper(amazonDynamoDB(), new TableNameOverride("user_access_token").config());
    }

    @Bean
    AccessTokenConverter accessTokenConverter() {
        return new AccessTokenConverter(new DefaultDynamoDBUserAccessTokenConverter(),
                new DefaultUserAccessTokenConverter());
    }
    
}

UserAccessTokenRepository.java

@Repository
public class UserAccessTokenRepository {

    @Autowired
    private DynamoDBMapper dynamoDBMapper;

    @Autowired
    private AccessTokenConverter accessTokenConverter;

    public UserAccessToken getUserAccessToken(Long uid) {

        DynamoDBUserAccessToken dynamoDBUserAccessToken = dynamoDBMapper.load(new DynamoDBUserAccessToken(uid));
        if (null != dynamoDBUserAccessToken) {
            accessTokenConverter.toUserAccessToken(dynamoDBUserAccessToken);
        }
        return null;

    }

    public void deleteUserAccessToken(Long uid) {
        dynamoDBMapper.delete(new DynamoDBUserAccessToken(uid));
    }

    public void saveUserAccessToken(UserAccessToken userAccessToken) {
        dynamoDBMapper.save(accessTokenConverter.toDynamoUserAccessToken(userAccessToken));
    }

}

至此，关键代码部分已罗列完毕