在這篇文章中，我們將使用Gradle和spring boot來創(chuàng)建一個集成spring-mvc和Apache Cassandra數(shù)據(jù)庫的項目。

首先，我們將從Gradle配置開始

group 'com.gkatzioura' version '1.0-SNAPSHOT'apply plugin: 'java' apply plugin: 'eclipse' apply plugin: 'idea' apply plugin: 'spring-boot'buildscript {repositories {mavenCentral()}dependencies {classpath("org.springframework.boot:spring-boot-gradle-plugin:1.2.5.RELEASE")} }jar {baseName = 'gs-serving-web-content'version = '0.1.0' }repositories {mavenCentral() }sourceCompatibility = 1.8repositories {mavenCentral() }dependencies {compile "org.springframework.boot:spring-boot-starter-thymeleaf"compile "org.springframework.data:spring-data-cassandra:1.2.2.RELEASE"compile 'org.slf4j:slf4j-api:1.6.6'compile 'ch.qos.logback:logback-classic:1.0.13'testCompile "junit:junit" }task wrapper(type: Wrapper) {gradleVersion = '2.3' }

我們將在我們的Cassandra數(shù)據(jù)庫中創(chuàng)建鍵空間和表：

CREATE KEYSPACE IF NOT EXISTS example WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'} AND durable_writes = true;CREATE TABLE IF NOT EXISTS example.greetings (user text,id timeuuid,greet text,creation_date timestamp,PRIMARY KEY (user, id) ) WITH CLUSTERING ORDER BY (id DESC);

我們可以使用cqlsh運行包含cql語句的文件

cqlsh -f database_creation.cql

Cassandra連接信息將位于META-INF / cassandra.properties中

cassandra.contactpoints=localhost cassandra.port=9042 cassandra.keyspace=example

現(xiàn)在，我們可以使用spring注釋繼續(xù)進行Cassandra配置。

package com.gkatzioura.spring.config;import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.Bean; import org.springframework.context.annotation.Configuration; import org.springframework.context.annotation.PropertySource; import org.springframework.core.env.Environment; import org.springframework.data.cassandra.config.CassandraClusterFactoryBean; import org.springframework.data.cassandra.config.CassandraSessionFactoryBean; import org.springframework.data.cassandra.config.SchemaAction; import org.springframework.data.cassandra.convert.CassandraConverter; import org.springframework.data.cassandra.convert.MappingCassandraConverter; import org.springframework.data.cassandra.core.CassandraOperations; import org.springframework.data.cassandra.core.CassandraTemplate; import org.springframework.data.cassandra.mapping.BasicCassandraMappingContext; import org.springframework.data.cassandra.mapping.CassandraMappingContext; import org.springframework.data.cassandra.repository.config.EnableCassandraRepositories;@Configuration @PropertySource(value = {"classpath:META-INF/cassandra.properties"}) @EnableCassandraRepositories(basePackages = {"com.gkatzioura.spring"}) public class CassandraConfig {@Autowiredprivate Environment environment;private static final Logger LOGGER = LoggerFactory.getLogger(CassandraConfig.class);@Beanpublic CassandraClusterFactoryBean cluster() {CassandraClusterFactoryBean cluster = new CassandraClusterFactoryBean();cluster.setContactPoints(environment.getProperty("cassandra.contactpoints"));cluster.setPort(Integer.parseInt(environment.getProperty("cassandra.port")));return cluster;}@Beanpublic CassandraMappingContext mappingContext() {return new BasicCassandraMappingContext();}@Beanpublic CassandraConverter converter() {return new MappingCassandraConverter(mappingContext());}@Beanpublic CassandraSessionFactoryBean session() throws Exception {CassandraSessionFactoryBean session = new CassandraSessionFactoryBean();session.setCluster(cluster().getObject());session.setKeyspaceName(environment.getProperty("cassandra.keyspace"));session.setConverter(converter());session.setSchemaAction(SchemaAction.NONE);return session;}@Beanpublic CassandraOperations cassandraTemplate() throws Exception {return new CassandraTemplate(session().getObject());}}

然后，我們創(chuàng)建Greeting實體。

package com.gkatzioura.spring.entity;import com.datastax.driver.core.utils.UUIDs; import org.springframework.cassandra.core.PrimaryKeyType; import org.springframework.data.cassandra.mapping.Column; import org.springframework.data.cassandra.mapping.PrimaryKeyColumn; import org.springframework.data.cassandra.mapping.Table;import java.util.Date; import java.util.UUID;@Table(value = "greetings") public class Greeting {@PrimaryKeyColumn(name = "id",ordinal = 1,type = PrimaryKeyType.CLUSTERED)private UUID id = UUIDs.timeBased();@PrimaryKeyColumn(name="user",ordinal = 0,type = PrimaryKeyType.PARTITIONED)private String user;@Column(value = "greet")private String greet;@Column(value = "creation_date")private Date creationDate;public UUID getId() {return id;}public void setId(UUID id) {this.id = id;}public Date getCreationDate() {return creationDate;}public void setCreationDate(Date creationDate) {this.creationDate = creationDate;}public String getUser() {return user;}public void setUser(String user) {this.user = user;}public String getGreet() {return greet;}public void setGreet(String greet) {this.greet = greet;} }

為了訪問數(shù)據(jù)，應該創(chuàng)建一個存儲庫。 在我們的案例中，我們將通過添加一些查詢來向存儲庫添加一些額外的功能。

package com.gkatzioura.spring.repository;import com.gkatzioura.spring.entity.Greeting; import org.springframework.data.cassandra.repository.CassandraRepository; import org.springframework.data.cassandra.repository.Query; import org.springframework.data.repository.NoRepositoryBean;import java.util.UUID;public interface GreetRepository extends CassandraRepository<Greeting> {@Query("SELECT*FROM greetings WHERE user=?0 LIMIT ?1")Iterable<Greeting> findByUser(String user,Integer limit);@Query("SELECT*FROM greetings WHERE user=?0 AND id<?1 LIMIT ?2")Iterable<Greeting> findByUserFrom(String user,UUID from,Integer limit);}

現(xiàn)在，我們可以實現(xiàn)控制器，以便通過http訪問數(shù)據(jù)。 通過郵寄，我們可以保存“問候語”實體。 通過獲取，我們可以獲取收到的所有問候。 通過指定用戶，我們可以使用Cassandra查詢來獲取特定用戶的問候。

package com.gkatzioura.spring.controller;import com.gkatzioura.spring.entity.Greeting; import com.gkatzioura.spring.repository.GreetRepository; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*;import java.util.ArrayList; import java.util.Date; import java.util.List;@RestController public class GreetingController {@Autowiredprivate GreetRepository greetRepository;@RequestMapping(value = "/greeting",method = RequestMethod.GET)@ResponseBodypublic List<Greeting> greeting() {List<Greeting> greetings = new ArrayList<>();greetRepository.findAll().forEach(e->greetings.add(e));return greetings;}@RequestMapping(value = "/greeting/{user}/",method = RequestMethod.GET)@ResponseBodypublic List<Greeting> greetingUserLimit(@PathVariable String user,Integer limit) {List<Greeting> greetings = new ArrayList<>();greetRepository.findByUser(user,limit).forEach(e -> greetings.add(e));return greetings;}@RequestMapping(value = "/greeting",method = RequestMethod.POST)@ResponseBodypublic String saveGreeting(@RequestBody Greeting greeting) {greeting.setCreationDate(new Date());greetRepository.save(greeting);return "OK";}}

最后但并非最不重要的是我們的Application類

package com.gkatzioura.spring;import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication public class Application {public static void main(String[] args) {SpringApplication.run(Application.class, args);}}

為了運行，只需運行：

gradle bootRun

翻譯自: https://www.javacodegeeks.com/2015/08/set-up-a-springdata-project-using-apache-cassandra.html

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