Java秒杀系统方案优化1

第1章 项目开发环境与框架搭建

前面项目搭建就跳过了，直接来到了搭建Mybatis这一步了。

1.搭建Mybatis

项目使用springboot +mybaits来搭建的，所以所有的配置信息都存放在了properties文件或者yml文件中，我在项目中使用哦的是properties文件，其中mybatis的配置信息如下：

# mybatis
mybatis.type-aliases-package=com.imooc.miaosha.domain
mybatis.configuration.map-underscore-to-camel-case=true
mybatis.configuration.default-fetch-size=100
mybatis.configuration.default-statement-timeout=3000
mybatis.mapperLocations = classpath:com/imooc/miaosha/dao/*.xml

mybatis.type-aliases-package：是别名的意思不需要写很长的包名
mybatis.mapperLocations：指定mapper问位置信息，就是指定到dao层
类似的登录dao如下:

@Mapper
public interface UserDao {

    @Select("select * from user where id = #{id}")
    public User getById(@Param("id")int id  );

    @Insert("insert into user(id, name)values(#{id}, #{name})")
    public int insert(User user);

}

必须要在类上写上@Mapper这样类才会被扫描到

同理的在service包上建立对应的UserService

@Service
public class UserService {

    @Autowired
    UserDao userDao;

    public User getById(int id) {
         return userDao.getById(id);
    }

}

每个的service层上的类也是需要用注解@Service来修饰的，然后注入dao层的类

@Autowired
UserDao userDao

2.集成redis

2.1. Linux上安装Redis

如何在Linux上安装Redis,可以百度查阅相关资料或者博主的博客

Linux安装Redis

2.2 项目上集成Redis

和搭建Mybatis一样相关的配置信息也是存放在properties上的，相关代码如下：

redis.host=127.0.0.1
redis.port=6379
redis.timeout=10
redis.password=myredis2018
redis.poolMaxTotal=1000
redis.poolMaxIdle=500
redis.poolMaxWait=500

PS这里所有与Redis相关的配置信息都用redis前缀做修饰，用于在BOOT中使用@ConfigurationProperties(prefix=”redis”)来把相关的信息导入

编写BEAN来获取配置信息，代码如下：

@Component
@ConfigurationProperties(prefix="redis")
public class RedisConfig {
    private String host;
    private int port;
    private int timeout;//秒
    private String password;
    private int poolMaxTotal;
    private int poolMaxIdle;
    private int poolMaxWait;//秒
    。。。省略GET SET    
}

@component （把普通pojo实例化到spring容器中，相当于配置文件中的）
@ConfigurationProperties(把properties中redis开头的信息注入到相关的属性中)

获取JedisPool，使用工厂来获取，相关代码如下：

@Service
public class RedisPoolFactory {

    @Autowired
    RedisConfig redisConfig;
    @Bean
    public JedisPool JedisPoolFactory() {
        JedisPoolConfig poolConfig = new JedisPoolConfig();
        poolConfig.setMaxIdle(redisConfig.getPoolMaxIdle());
        poolConfig.setMaxTotal(redisConfig.getPoolMaxTotal());
        poolConfig.setMaxWaitMillis(redisConfig.getPoolMaxWait() * 1000);
        JedisPool jp = new JedisPool(poolConfig, redisConfig.getHost(), redisConfig.getPort(),
                redisConfig.getTimeout()*1000, redisConfig.getPassword(), 0);
        return jp;
    }
}

注入redisConfig，然后通过get方法获取配置信息new一个JedisPool 并且使用@Bean把这个JedisPool 放入容器中

---

编写项目中redis的Service类，把redis的一些常用的get，set，exists，detete，incr，decr封装，并且把该类放入容器中，以便其他Service调用，具体的代码如下

@Service
public class RedisService {

    @Autowired
    JedisPool jedisPool;

    /**
     * 获取当个对象
     * */
    public  T get(KeyPrefix prefix, String key,  Class clazz) {
         Jedis jedis = null;
         try {
             jedis =  jedisPool.getResource();
             //生成真正的key
             String realKey  = prefix.getPrefix() + key;
             String  str = jedis.get(realKey);
             T t =  stringToBean(str, clazz);
             return t;
         }finally {
              returnToPool(jedis);
         }
    }

    /**
     * 设置对象
     * */
    public  boolean set(KeyPrefix prefix, String key,  T value) {
         Jedis jedis = null;
         try {
             jedis =  jedisPool.getResource();
             String str = beanToString(value);
             if(str == null || str.length() <= 0) {
                 return false;
             }
            //生成真正的key
             String realKey  = prefix.getPrefix() + key;
             int seconds =  prefix.expireSeconds();
             if(seconds <= 0) {
                 jedis.set(realKey, str);
             }else {
                 jedis.setex(realKey, seconds, str);
             }
             return true;
         }finally {
              returnToPool(jedis);
         }
    }

    /**
     * 判断key是否存在
     * */
    public  boolean exists(KeyPrefix prefix, String key) {
         Jedis jedis = null;
         try {
             jedis =  jedisPool.getResource();
            //生成真正的key
             String realKey  = prefix.getPrefix() + key;
            return  jedis.exists(realKey);
         }finally {
              returnToPool(jedis);
         }
    }

    /**
     * 删除
     * */
    public boolean delete(KeyPrefix prefix, String key) {
         Jedis jedis = null;
         try {
             jedis =  jedisPool.getResource();
            //生成真正的key
            String realKey  = prefix.getPrefix() + key;
            long ret =  jedis.del(realKey);
            return ret > 0;
         }finally {
              returnToPool(jedis);
         }
    }

    /**
     * 增加值
     * */
    public  Long incr(KeyPrefix prefix, String key) {
         Jedis jedis = null;
         try {
             jedis =  jedisPool.getResource();
            //生成真正的key
             String realKey  = prefix.getPrefix() + key;
            return  jedis.incr(realKey);
         }finally {
              returnToPool(jedis);
         }
    }

    /**
     * 减少值
     * */
    public  Long decr(KeyPrefix prefix, String key) {
         Jedis jedis = null;
         try {
             jedis =  jedisPool.getResource();
            //生成真正的key
             String realKey  = prefix.getPrefix() + key;
            return  jedis.decr(realKey);
         }finally {
              returnToPool(jedis);
         }
    }

    public boolean delete(KeyPrefix prefix) {
        if(prefix == null) {
            return false;
        }
        List keys = scanKeys(prefix.getPrefix());
        if(keys==null || keys.size() <= 0) {
            return true;
        }
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            jedis.del(keys.toArray(new String[0]));
            return true;
        } catch (final Exception e) {
            e.printStackTrace();
            return false;
        } finally {
            if(jedis != null) {
                jedis.close();
            }
        }
    }

    public List scanKeys(String key) {
        Jedis jedis = null;
        try {
            jedis = jedisPool.getResource();
            List keys = new ArrayList();
            String cursor = "0";
            ScanParams sp = new ScanParams();
            sp.match("*"+key+"*");
            sp.count(100);
            do{
                ScanResult ret = jedis.scan(cursor, sp);
                List result = ret.getResult();
                if(result!=null && result.size() > 0){
                    keys.addAll(result);
                }
                //再处理cursor
                cursor = ret.getStringCursor();
            }while(!cursor.equals("0"));
            return keys;
        } finally {
            if (jedis != null) {
                jedis.close();
            }
        }
    }

    public static  String beanToString(T value) {
        if(value == null) {
            return null;
        }
        Class clazz = value.getClass();
        if(clazz == int.class || clazz == Integer.class) {
             return ""+value;
        }else if(clazz == String.class) {
             return (String)value;
        }else if(clazz == long.class || clazz == Long.class) {
            return ""+value;
        }else {
            return JSON.toJSONString(value);
        }
    }

    @SuppressWarnings("unchecked")
    public static  T stringToBean(String str, Class clazz) {
        if(str == null || str.length() <= 0 || clazz == null) {
             return null;
        }
        if(clazz == int.class || clazz == Integer.class) {
             return (T)Integer.valueOf(str);
        }else if(clazz == String.class) {
             return (T)str;
        }else if(clazz == double.class || clazz == Double.class) {
            return (T)Double.valueOf(str);
        }else if(clazz == long.class || clazz == Long.class) {
            return  (T)Long.valueOf(str);
        }else {
            return JSON.toJavaObject(JSON.parseObject(str), clazz);
        }
    }

    private void returnToPool(Jedis jedis) {
         if(jedis != null) {
             jedis.close();
         }
    }

}