We will build an application that demonstrates how to perform CRUD operations Redis<\/strong> through a web interface. The full source code for this project is available on Github<\/a>.<\/p>\n Redis is an open source, in-memory\u00a0key-value data store<\/a>, used as a database, cache and message broker. In terms of implementation, Key Value stores represent one of the largest and oldest members in the NoSQL space. Redis supports data structures such as strings, hashes, lists, sets, and sorted sets with range queries.<\/p>\n The Spring Data Redis\u00a0 framework<\/a> makes it easy to write Spring applications that use the Redis key value store by providing an abstraction to the data store.<\/p>\n The server is available for free at\u00a0http:\/\/redis.io\/download<\/a>.<\/p>\n If you use a Mac, you can install it with homebrew:<\/p>\n Then start the server:<\/p>\n <\/p>\n Let\u2019s declare the necessary dependencies in our pom.xml<\/em> for the example application we are building:<\/p>\n <\/p>\n We need to connect our application with the Redis server. To establish this connection, we are using Jedis<\/a>, a Redis client implementation.<\/p>\n Let\u2019s start with the configuration bean definitions:<\/p>\n The JedisConnectionFactory<\/em> is made into a bean so we can create a RedisTemplate<\/em> to query data. Following the principles of SOLID<\/a>, we create a MessagePublisher<\/em> interface:<\/p>\n We implement the MessagePublisher<\/em> interface to use the high-level RedisTemplate to publish the message since the RedisTemplate allows arbitrary objects to be passed in as messages:<\/p>\n We also define this as a bean in RedisConfig<\/em>:<\/p>\n In order to subscribe to messages, we need to implement the MessageListener<\/em> interface: each time a new message arrives, a callback gets invoked and the user code executed through a method named onMessage<\/em>. This interface gives access to the message, the channel it has been received through, and any pattern used by the subscription to match the channel.<\/p>\n Thus, we create a service class to implement MessageSubscriber<\/em>:<\/p>\n We add a bean definition to RedisConfig<\/em>:<\/p>\n Now that we have configured the application to interact with the Redis server, we are going to prepare the application to take example data.<\/p>\n For this example, we defining a Movie<\/em> model with two fields:<\/p>\n Unlike other Spring Data projects, Spring Data Redis does offer any features to build on top of the other Spring Data interfaces<\/strong>. This is odd for us who have experience with the other Spring Data projects.<\/p>\n Often there is no need to write an implementation of a repository interface with Spring Data projects. We simply just interact with the interface. Spring Data JPA provides numerous repository interfaces that can be extended to get features such as CRUD operations, derived queries, and paging.<\/p>\n So, unfortunately, we need to write our own interface<\/strong> and then define the methods:<\/p>\n Our implementation class uses\u00a0the\u00a0redisTemplate<\/em>\u00a0defined in our configuration class RedisConfig<\/em>.<\/p>\n We use the HashOperations<\/em> template that Spring Data Redis offers:<\/p>\n Let\u2019s take note of the\u00a0init()\u00a0<\/em>method. In this method, we use a function named\u00a0opsForHash(), <\/em>which\u00a0returns the operations performed on hash values bound to the given key. We then use the\u00a0hashOps<\/em>, which was defined in init(), for all our CRUD operations.<\/p>\n In this section, we will review adding Redis CRUD operations capabilities to a web interface.<\/p>\n We want to be able to add a Movie in our web page. The Key is the is the Movie id<\/em> and the Value is the actual object. However, we will later address this so only the Movie name is shown as the value.<\/p>\n So, let\u2019s add a form to a HTML document and assign appropriate names and ids :<\/p>\n Now we use JavaScript to persist the values on form submission:<\/p>\n We assign the @RequestMapping<\/em> value for the POST request, request the key and value, create a Movie<\/em> object, and save it to the repository:<\/p>\n Once a Movie\u00a0<\/em>object is added, we refresh the table to display an updated table. In our JavaScript code block for section 7.1, we called a JavaScript function called\u00a0refreshTable()<\/em>. This function performs a GET request to retrieve the current data in the repository:<\/p>\n The GET request is processed by a method named findAll()<\/em> that retrieves all the Movie<\/em> objects stored in the repository and then converts the datatype from Map<Object, Object><\/em> to Map<String, String><\/em>:<\/p>\n We write Javascript to do a POST request to\u00a0<\/em>\/delete<\/em>, refresh the table, and set keyboard focus to key input:<\/p>\n We request the key and delete the object in the redisRepository\u00a0<\/em>based on this key:<\/p>\n Here we added two movies: Here we removed one movie: In this tutorial, we introduced Spring Data Redis and one way of connecting it to a web application to perform CRUD operations.<\/p>\n The source code for the example application is on Github<\/a>.<\/p>\n2. What is Redis?<\/h2>\n
3. Setting Up A Redis Server<\/h2>\n
brew install redis<\/pre>\n
mikes-MacBook-Air:~ mike$ redis-server\r\n10699:C 23 Nov 08:35:58.306 # oO0OoO0OoO0Oo Redis is starting oO0OoO0OoO0Oo\r\n10699:C 23 Nov 08:35:58.307 # Redis version=4.0.2, bits=64, commit=00000000, modified=0, pid=10699, just started\r\n10699:C 23 Nov 08:35:58.307 # Warning: no config file specified, using the default config. In order to specify a config file use redis-server \/path\/to\/redis.conf\r\n10699:M 23 Nov 08:35:58.309 * Increased maximum number of open files to 10032 (it was originally set to 256).\r\n _._ \r\n _.-``__ ''-._ \r\n _.-`` `. `_. ''-._ Redis 4.0.2 (00000000\/0) 64 bit\r\n .-`` .-```. ```\\\/ _.,_ ''-._ \r\n ( ' , .-` | `, ) Running in standalone mode\r\n |`-._`-...-` __...-.``-._|'` _.-'| Port: 6379\r\n | `-._ `._ \/ _.-' | PID: 10699\r\n `-._ `-._ `-.\/ _.-' _.-' \r\n |`-._`-._ `-.__.-' _.-'_.-'| \r\n | `-._`-._ _.-'_.-' | http:\/\/redis.io \r\n `-._ `-._`-.__.-'_.-' _.-' \r\n |`-._`-._ `-.__.-' _.-'_.-'| \r\n | `-._`-._ _.-'_.-' | \r\n `-._ `-._`-.__.-'_.-' _.-' \r\n `-._ `-.__.-' _.-' \r\n `-._ _.-' \r\n `-.__.-' \r\n\r\n10699:M 23 Nov 08:35:58.312 # Server initialized\r\n10699:M 23 Nov 08:35:58.312 * Ready to accept connections<\/pre>\n
4. Maven Dependencies<\/h2>\n
<dependency>\r\n\t\t\t<groupId>org.springframework.boot<\/groupId>\r\n\t\t\t<artifactId>spring-boot-starter-data-redis<\/artifactId>\r\n\t\t<\/dependency>\r\n\t\t<dependency>\r\n\t\t\t<groupId>org.springframework.boot<\/groupId>\r\n\t\t\t<artifactId>spring-boot-starter-thymeleaf<\/artifactId>\r\n\t\t<\/dependency>\r\n\t\t<dependency>\r\n\t\t\t<groupId>org.springframework.boot<\/groupId>\r\n\t\t\t<artifactId>spring-boot-starter-web<\/artifactId>\r\n\t\t<\/dependency><\/pre>\n
5. Redis Configuration<\/h2>\n
5.1 Config<\/h3>\n
@Bean\r\n JedisConnectionFactory jedisConnectionFactory() {\r\n return new JedisConnectionFactory();\r\n }\r\n\r\n @Bean\r\n public RedisTemplate<String, Object> redisTemplate() {\r\n final RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();\r\n template.setConnectionFactory(jedisConnectionFactory());\r\n template.setValueSerializer(new GenericToStringSerializer<Object>(Object.class));\r\n return template;\r\n }<\/pre>\n5.2 Message Publisher<\/h3>\n
public interface MessagePublisher {\r\n\r\n void publish(final String message);\r\n}<\/pre>\n@Service\r\npublic class MessagePublisherImpl implements MessagePublisher {\r\n \r\n @Autowired\r\n private RedisTemplate<String, Object> redisTemplate;\r\n @Autowired\r\n private ChannelTopic topic;\r\n\r\n public MessagePublisherImpl() {\r\n }\r\n\r\n public MessagePublisherImpl(final RedisTemplate<String, Object> redisTemplate, final ChannelTopic topic) {\r\n this.redisTemplate = redisTemplate;\r\n this.topic = topic;\r\n }\r\n\r\n public void publish(final String message) {\r\n redisTemplate.convertAndSend(topic.getTopic(), message);\r\n }\r\n\r\n}<\/pre>\n@Bean\r\n MessagePublisher redisPublisher() {\r\n return new MessagePublisherImpl(redisTemplate(), topic());\r\n }<\/pre>\nMessage Listener<\/h3>\n
@Service\r\npublic class MessageSubscriber implements MessageListener {\r\n \r\n public static List<String> messageList = new ArrayList<String>();\r\n\r\n public void onMessage(final Message message, final byte[] pattern) {\r\n messageList.add(message.toString());\r\n System.out.println(\"Message received: \" + new String(message.getBody()));\r\n }\r\n\r\n}<\/pre>\n@Bean\r\n MessageListenerAdapter messageListener() {\r\n return new MessageListenerAdapter(new MessageSubscriber());\r\n }<\/pre>\n6. RedisRepository<\/h2>\n
6.1 Model<\/h3>\n
private String id;\r\nprivate String name;\r\n\/\/standard getters and setters<\/pre>\n
6.2 Repository interface<\/h3>\n
public interface RedisRepository {\r\n\r\n Map<Object, Object> findAllMovies();\r\n\r\n void add(Movie movie);\r\n\r\n void delete(String id);\r\n\r\n Movie findMovie(String id);\r\n \r\n}<\/pre>\n6.3 Repository implementation<\/h3>\n
@Repository\r\npublic class RedisRepositoryImpl implements RedisRepository {\r\n private static final String KEY = \"Movie\";\r\n \r\n private RedisTemplate<String, Object> redisTemplate;\r\n private HashOperations hashOperations;\r\n \r\n @Autowired\r\n public RedisRepositoryImpl(RedisTemplate<String, Object> redisTemplate){\r\n this.redisTemplate = redisTemplate;\r\n }\r\n\r\n @PostConstruct\r\n private void init(){\r\n hashOperations = redisTemplate.opsForHash();\r\n }\r\n \r\n public void add(final Movie movie) {\r\n hashOperations.put(KEY, movie.getId(), movie.getName());\r\n }\r\n\r\n public void delete(final String id) {\r\n hashOperations.delete(KEY, id);\r\n }\r\n \r\n public Movie findMovie(final String id){\r\n return (Movie) hashOperations.get(KEY, id);\r\n }\r\n \r\n public Map<Object, Object> findAllMovies(){\r\n return hashOperations.entries(KEY);\r\n }\r\n\r\n \r\n}<\/pre>\n7. Web interface<\/h2>\n
7.1 Add A Movie<\/h3>\n
<form id=\"addForm\">\r\n<div class=\"form-group\">\r\n <label for=\"keyInput\">Movie ID (key)<\/label>\r\n <input name=\"keyInput\" id=\"keyInput\" class=\"form-control\"\/>\r\n <\/div>\r\n<div class=\"form-group\">\r\n <label for=\"valueInput\">Movie Name (field of Movie object value)<\/label>\r\n <input name=\"valueInput\" id=\"valueInput\" class=\"form-control\"\/>\r\n <\/div>\r\n <button class=\"btn btn-default\" id=\"addButton\">Add<\/button>\r\n <\/form><\/pre>\n
$(document).ready(function() {\r\n var keyInput = $('#keyInput'),\r\n valueInput = $('#valueInput');\r\n\r\n refreshTable();\r\n $('#addForm').on('submit', function(event) {\r\n var data = {\r\n key: keyInput.val(),\r\n value: valueInput.val()\r\n };\r\n\r\n $.post('\/add', data, function() {\r\n refreshTable();\r\n keyInput.val('');\r\n valueInput.val('');\r\n keyInput.focus();\r\n });\r\n event.preventDefault();\r\n });\r\n\r\n keyInput.focus();\r\n});<\/pre>\n@RequestMapping(value = \"\/add\", method = RequestMethod.POST)\r\n public ResponseEntity<String> add(\r\n @RequestParam String key,\r\n @RequestParam String value) {\r\n \r\n Movie movie = new Movie(key, value);\r\n \r\n redisRepository.add(movie);\r\n return new ResponseEntity<>(HttpStatus.OK);\r\n }<\/pre>\n7.2 Viewing the content<\/h3>\n
function refreshTable() {\r\n $.get('\/values', function(data) {\r\n var attr,\r\n mainTable = $('#mainTable tbody');\r\n mainTable.empty();\r\n for (attr in data) {\r\n if (data.hasOwnProperty(attr)) {\r\n mainTable.append(row(attr, data[attr]));\r\n }\r\n }\r\n });\r\n}<\/pre>\n@RequestMapping(\"\/values\")\r\n public @ResponseBody Map<String, String> findAll() {\r\n Map<Object, Object> aa = redisRepository.findAllMovies();\r\n Map<String, String> map = new HashMap<String, String>();\r\n for(Map.Entry<Object, Object> entry : aa.entrySet()){\r\n String key = (String) entry.getKey();\r\n map.put(key, aa.get(key).toString());\r\n }\r\n return map;\r\n }<\/pre>\n7.3 Delete a Movie<\/h3>\n
function deleteKey(key) {\r\n $.post('\/delete', {key: key}, function() {\r\n refreshTable();\r\n $('#keyInput').focus();\r\n });\r\n}<\/pre>\n@RequestMapping(value = \"\/delete\", method = RequestMethod.POST)\r\n public ResponseEntity<String> delete(@RequestParam String key) {\r\n redisRepository.delete(key);\r\n return new ResponseEntity<>(HttpStatus.OK);\r\n }<\/pre>\n8. Demo<\/h2>\n
\n![\"\"](\"http:\/\/www.javacodegeeks.com\/wp-content\/uploads\/2017\/11\/add-key-redis-springboot.png\")
<\/a><\/p>\n
\n![\"\"](\"http:\/\/www.javacodegeeks.com\/wp-content\/uploads\/2017\/11\/delete-key-redis-springboot.png\")
<\/a><\/p>\n9. Conclusion<\/h2>\n