springboot學習筆記-4 整合Druid數據源和使用@Cache簡化redis配置

一.整合Druid數據源

　　Druid是一個關系型數據庫連接池,是阿里巴巴的一個開源項目,Druid在監控,可擴展性,穩定性和性能方面具有比較明顯的優勢.通過Druid提供的監控功能,可以實時觀察數據庫連接池和SQL查詢的工作情況.使用Druid在一定程度上可以提高數據庫的訪問技能.

　　1.1 在pom.xml中添加依賴

<dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.0.18</version>
</dependency>

　　1.2 Druid數據源配置

　　在application.properties中,去書寫Druid數據源的配置信息.

##Druid##
spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.url=jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8
spring.datasource.username=root
spring.datasource.password=root
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
spring.datasource.maxWait=60000
spring.datasource.timeBetweenEvictionRunsMillis=60000
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1 FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false
spring.datasource.poolPreparedStatements=true
spring.datasource.maxPoolPreparedStatementPerConnectionSize=20
spring.datasource.filters=stat,wall,log4j
spring.datasource.connectionProperties=druid.stat.mergeSql=true;druid.stat.slowSqlMillis=5000
spring.datasource.useGlobalDataSourceStat=true

　　1.3 建立DruidConfiguration配置類,配置過濾信息

@Configuration
public class DruidConfiguration {
    @Bean
    public ServletRegistrationBean statViewServle(){
        ServletRegistrationBean servletRegistrationBean = new ServletRegistrationBean(new StatViewServlet(),"/druid/*");
        //白名單：
        servletRegistrationBean.addInitParameter("allow","192.168.1.218,127.0.0.1");
        //IP黑名單 (存在共同時，deny優先於allow) : 如果滿足deny的即提示:Sorry, you are not permitted to view this page.
        servletRegistrationBean.addInitParameter("deny","192.168.1.100");
        //登錄查看信息的賬號密碼.
        servletRegistrationBean.addInitParameter("loginUsername","druid");
        servletRegistrationBean.addInitParameter("loginPassword","12345678");
        //是否能夠重置數據.
        servletRegistrationBean.addInitParameter("resetEnable","false");
        return servletRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean statFilter(){
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(new WebStatFilter());
        //添加過濾規則.
        filterRegistrationBean.addUrlPatterns("/*");
        //添加不需要忽略的格式信息.
        filterRegistrationBean.addInitParameter("exclusions","*.js,*.gif,*.jpg,*.png,*.css,*.ico,/druid/*");
        return filterRegistrationBean;
        }
}

　　1.4 配置數據源的信息

　　告訴springboot采用Druid數據源:

 @Bean(name = "dataSource")
     @Primary
     @ConfigurationProperties(prefix = "spring.datasource")
     public DataSource dataSource(){
         return DataSourceBuilder.create().type(com.alibaba.druid.pool.DruidDataSource.class).build();
     }

　　接下來就可以通過localhost:8080/druid/index.html去打開控制台,觀察過濾信息了!

二.使用@Cache簡化redis配置

　　在實體類比較簡單的時候(例如:沒有一對多,多對多這類復雜的關系,不是List,Map這類數據類型,只是一個Pojo類),可以使用@Cache去替代書寫BeanRedis注入RedisTemplate的方式去訪問Redis數據庫.

　　2.1 建立RoleService.采用@Cacheable和@CachePut去訪問Redis

　　實體類的主要屬性如下：

@Service
public class RoleService {
    @Autowired
    private RoleRepository roleRepository;
    @Autowired
    private RoleRedis roleRedis;


    @Cacheable(value = "mysql:findById:role", keyGenerator = "simpleKey")
    public Role findById(Long id) {
        System.out.println("從數據庫中查詢");
        return roleRepository.findOne(id);
    }

    @CachePut(value = "mysql:findById:role", keyGenerator = "objectId")
    public Role create(Role role) {
        System.out.println("************在數據庫中創建************");
        return roleRepository.save(role);
    }
    //簡單的操作使用注解的形式
    @CachePut(value = "mysql:findById:role", keyGenerator = "objectId")
    public Role update(Role role) {
        System.out.println("************在數據庫中更新************");
        return roleRepository.save(role);
    }

    @CacheEvict(value = "mysql:findById:role", keyGenerator = "simpleKey")
    public void delete(Long id) {
        System.out.println("************在數據庫中銷毀************");
        roleRepository.delete(id);
    }

    public List<Role> findAll(){
        List<Role> roleList = roleRedis.getList("mysql:findAll:role");
        if(roleList == null) {
            roleList = roleRepository.findAll();
            if(roleList != null)
                roleRedis.add("mysql:findAll:role", 5L, roleList);
        }
        return roleList;
    }
    //復雜的依然使用RedisTemplate的形式
    public Page<Role> findPage(RoleQo roleQo){
       Pageable pageable = new PageRequest(roleQo.getPage(), roleQo.getSize(), new Sort(Sort.Direction.ASC, "id"));

        PredicateBuilder pb  = new PredicateBuilder();

        if (!StringUtils.isEmpty(roleQo.getName())) {
            pb.add("name","%" + roleQo.getName() + "%", LinkEnum.LIKE);
        }

        Page<Role> pages = roleRepository.findAll(pb.build(), Operator.AND, pageable);
        return pages;
    }

}

　注意,@Cacheable放置於方法上,當調用這個方法時,程序會先根據key(value加上KeyGenerator生成的key)去尋找有沒有對應的對象結果,如果有的話,直接返回,沒有才執行方法(從數據庫找).而@CachePut則會更新Redis緩存,同時執行對應的方法.@CacheEvict會刪除Redis緩存對應的對象.　

　2.2 建立Redis配置類,需要去配置Redis的注解

@ConfigurationProperties("application.properties")
@Configuration
@EnableCaching
public class RedisConfig extends CachingConfigurerSupport {

     @Value("${spring.redis.hostName}")
        private String hostName;
        @Value("${spring.redis.port}")
        private Integer port;
        
        @Bean
        public RedisConnectionFactory redisConnectionFactory() {
            JedisConnectionFactory cf = new JedisConnectionFactory();  
            cf.setHostName(hostName);  
            cf.setPort(port); 
            cf.afterPropertiesSet();  
            return cf;  
        }
    //配置key的生成
    @Bean
    public KeyGenerator simpleKey(){
        return new KeyGenerator() {
            @Override
            public Object generate(Object target, Method method, Object... params) {
                StringBuilder sb = new StringBuilder();
                sb.append(target.getClass().getName()+":");
                for (Object obj : params) {
                    sb.append(obj.toString());
                }
                return sb.toString();
            }
        };
    }
  //配置key的生成
    @Bean
    public KeyGenerator objectId(){
        return new KeyGenerator() {
            @Override
            public Object generate(Object target, Method method, Object... params){
                StringBuilder sb = new StringBuilder();
                sb.append(target.getClass().getName()+":");
                try {
                    sb.append(params[0].getClass().getMethod("getId", null).invoke(params[0], null).toString());
                }catch (NoSuchMethodException no){
                    no.printStackTrace();
                }catch(IllegalAccessException il){
                    il.printStackTrace();
                }catch(InvocationTargetException iv){
                    iv.printStackTrace();
                }
                return sb.toString();
            }
        };
    }
    //配置注解
    @Bean
    public CacheManager cacheManager(@SuppressWarnings("rawtypes") RedisTemplate redisTemplate) {
        RedisCacheManager manager = new RedisCacheManager(redisTemplate);
        manager.setDefaultExpiration(43200);//12小時
        return manager;
    }
    //對於復雜的屬性仍然使用RedisTemplate
    @Bean
    public RedisTemplate<String, String> redisTemplate(
            RedisConnectionFactory factory) {
        StringRedisTemplate template = new StringRedisTemplate(factory);
        Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);
        ObjectMapper om = new ObjectMapper();
        om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        jackson2JsonRedisSerializer.setObjectMapper(om);
        template.setValueSerializer(jackson2JsonRedisSerializer);
        template.afterPropertiesSet();
        return template;
    }

}

　　2.3 測試