分布式session

分布式session共享问题：
原因：
在集群环境中，当客户端发来一个请求，在请求到某台服务器，会在这台服务器上创建sesssion，并且将sessionId存放在响应头中返回，浏览器保存在本地，下次请求，将sessionId存放在请求头中，当下次请求的时候可能请求到的是集群中的另一台服务器，session为空，如果第一次创建session参数设置为true，默认也为true,则会在新的服务器上创建一个新的session，覆盖之前的sessionId,如果设置为false，则不会创建新的session,但都是取不到相应的key-value数据；
解决办法：
使用spring-session框架 将session存放到redis缓存中；

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
        <relativePath /> <!-- lookup parent from repository -->
    </parent>
    <properties>
        <weixin-java-mp.version>2.8.0</weixin-java-mp.version>
        <maven.compiler.source>1.8</maven.compiler.source>
        <maven.compiler.target>1.8</maven.compiler.target>
        <maven.compiler.encoding>UTF-8</maven.compiler.encoding>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.build.locales>zh_CN</project.build.locales>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <!-- <exclusions> <exclusion> <groupId>com.fasterxml.jackson.core</groupId> 
                <artifactId>jackson-databind</artifactId> </exclusion> </exclusions> -->
        </dependency>
        <!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
        <!-- Testing Dependencies -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <!--spring session 与redis应用基本环境配置,需要开启redis后才可以使用，不然启动Spring boot会报错 -->
        <dependency>
            <groupId>org.springframework.session</groupId>
            <artifactId>spring-session-data-redis</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
        </dependency>
        <dependency>
            <groupId>redis.clients</groupId>
            <artifactId>jedis</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <maimClass>com.meiteedu.WxMpApplication</maimClass>
                </configuration>
                <executions>
                    <execution>
                        <goals>
                            <goal>repackage</goal>
                        </goals>
                    </execution>
                </executions>
            </plugin>
        </plugins>
    </build>

import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.session.data.redis.config.annotation.web.http.EnableRedisHttpSession;

//这个类用配置redis服务器的连接
//maxInactiveIntervalInSeconds为SpringSession的过期时间（单位：秒）
@EnableRedisHttpSession(maxInactiveIntervalInSeconds = 1800)
public class SessionConfig {

    // 冒号后的值为没有配置文件时，制动装载的默认值
    @Value("${redis.hostname:localhost}")
    String HostName;
    @Value("${redis.port:6379}")
    int Port;

    @Bean
    public JedisConnectionFactory connectionFactory() {
        JedisConnectionFactory connection = new JedisConnectionFactory();
        connection.setPort(Port);
        connection.setHostName(HostName);
        return connection;
    }
}

//初始化Session配置
public class SessionInitializer extends AbstractHttpSessionApplicationInitializer{
    public SessionInitializer() {
        super(SessionConfig.class);
    }
}

应用Token令牌方式替换sesion，因为token本来就是存放在redis里边的；

@Service
public class TokenService {
    @Autowired
    private RedisService redisService;

    // 新增 返回token
    public String put(Object object) {
        String token = getToken();
        redisService.setString(token, object);
        return token;
    }

    // 获取信息
    public String get(String token) {
        String reuslt = redisService.getString(token);
        return reuslt;
    }

    public String getToken() {
        return UUID.randomUUID().toString();
    }

}

@RestController
public class TokenController {
    @Autowired
    private TokenService tokenService;
    @Value("${server.port}")
    private String serverPort;

    @RequestMapping("/put")
    public String put(String nameValue) {
        String token = tokenService.put(nameValue);
        return token + "-" + serverPort;
    }

    @RequestMapping("/get")
    public String get(String token) {
        String value = tokenService.get(token);
        return value + "-" + serverPort;
    }

}

itmayiedu_session.zip 分布式Session一致性问题.docx