使用Spring-Data-Redis存储对象(redisTemplate)

Redis是一种nosql数据库，在开发中常用做缓存。Jedis是Redis在java中的redis- client.在此之前，希望已经了解redis的基本使用和Maven的使用。建立Maven Project之后，在POM.xml中添加jedis和spring-data-redis的依赖如下：

 <dependency>
     <groupId>redis.clientsgroupId>
     <artifactId>jedisartifactId>
     <version>2.0.0version>
     <type>jartype>
     <scope>compilescope>
 dependency>

 <dependency>
     <groupId>org.springframework.datagroupId>
     <artifactId>spring-data-redisartifactId>
     <version>1.0.0.RELEASEversion>
 dependency>

Redis连接数据库参数如下：applicationContext-redis.properties

 #redis config
 redis.pool.maxActive=100
 redis.pool.maxIdle=20
 redis.pool.maxWait=1000
 redis.pool.testOnBorrow=true
 redis.hostname=localhost
 redis.port=6379
 redis.password=

在上下文配置中使用key-value读取方式读取properties中的值：

 <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig">
     <property name="maxActive" value="${redis.pool.maxActive}" />
     <property name="maxIdle" value="${redis.pool.maxIdle}" />
     <property name="maxWait" value="${redis.pool.maxWait}" />
     <property name="testOnBorrow" value="${redis.pool.testOnBorrow}" />
 bean>

 <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
     <property name="hostName" value="${redis.hostname}" />
     <property name="port" value="${redis.port}" />
     <property name="password" value="${redis.password}" />
     <property name="poolConfig" ref="jedisPoolConfig" />
 bean>
 >
 <bean id="redisTemplate" class="org.springframework.data.redis.core.RedisTemplate"                                   p:connection-factory-ref="jedisConnectionFactory" />

上面redisTemplate已经基本配置完成。

接下来创建User类，必须实现或者间接实现Serializable接口：

Redis存储对象是使用序列化，spring-data-redis已经将序列化的功能内置，不需要我们去管，我们只需要调用api就可以使用。SerialVersionUID字段对序列化扩展有用，为了以后扩展或者缩减字段时不会造成反序列化出错。

 public class User implements Serializable {

     private static final long serialVersionUID = -7898194272883238670L;

     public static final String OBJECT_KEY = "USER";

     public User() {
     }

     public User(String id) {
     }

     public User(String id, String name) {
         this.id = id;
         this.name = name;
     }

     private String id;

     private String name;

     public String getId() {
         return id;
     }

     public void setId(String id) {
         this.id = id;
     }

     public String getName() {
         return name;
     }

     public void setName(String name) {
         this.name = name;
     }

     public String toString() {
         return "User [id=" + id + ", name=" + name + "]";
     }

     public String getKey() {
         return getId();
     }

     public String getObjectKey() {
         return OBJECT_KEY;
     }
 }

创建userService类来操作redis增删查改缓存对象。

 public class UserService {

     RedisTemplate redisTemplate;

     public RedisTemplate getRedisTemplate() {
         return redisTemplate;
     }

     public void setRedisTemplate(RedisTemplate redisTemplate) {
         this.redisTemplate = redisTemplate;
     }

     public void put(User user) {
         redisTemplate.opsForHash().put(user.getObjectKey(), user.getKey(), user);
     }

     public void delete(User key) {
         redisTemplate.opsForHash().delete(key.getObjectKey(), key.getKey());
     }

     public User get(User key) {
         return (User) redisTemplate.opsForHash().get(key.getObjectKey(), key.getKey());
     }
 }

在上下文中配置redisTemplate注入，在使用bean方式来注入时，redisTemplate必须有setter/getter方法：

 <bean id="userService" class="Service.UserService">
     <property name="redisTemplate">
         <ref bean="redisTemplate" />
     property>
 bean>

======如果使用注解方式自动注入，则可以注释掉上面的bean配置方式======

在UserService注解@Service(“userService”),也可以在Service里写名字，默认是第一字母小写。

 @Service("userService")
 public class UserService {

     @Autowired
     RedisTemplate redisTemplate;
     ……
         ……
 }

在上下文配置文件中，添加自动扫描包的context节点，Base-package的路径要覆盖包含注解的类文件：

 <context:component-scan base-package="*" />

在main中来简单操作一下：

 public class Main {
     public static void main( String[] args )
     {
         ApplicationContext applicationContext = new ClassPathXmlApplicationContext("classpath*:/conf/applicationContext.xml"        );
         UserService userService =  (UserService) applicationContext.getBean("userService");

         User user1 = new User("user1ID", "User 1");
         User user2 = new User("user2ID", "User 2");

         System.out.println("==== getting objects from redis ====");
         System.out.println("User is not in redis yet: " + userService.get(user1));
         System.out.println("User is not in redis yet: " + userService.get(user2));

         System.out.println("==== putting objects into redis ====");
         userService.put(user1);
         userService.put(user2);

         System.out.println("==== getting objects from redis ====");
         System.out.println("User should be in redis yet: " + userService.get(user1));
         System.out.println("User should be in redis yet: " + userService.get(user2));

         System.out.println("==== deleting objects from redis ====");
         userService.delete(user1);
         userService.delete(user2);

         System.out.println("==== getting objects from redis ====");
         System.out.println("User is not in redis yet: " + userService.get(user1));
         System.out.println("User is not in redis yet: " + userService.get(user2));

     }
 }

确保redis服务器是开启状态之后就可以运行程序。运行结果如下：