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未优化前：课程检索库中的数据经过一次同步后固定不变，用户搜索到对应的课程后点击跳转到课程详情页面，进行选课
存在的问题：
- 用户使用不友好，搜索就是为了进行选课，应该返回对应课程的余量，如果没有余量了，进行友好提示，如果有余量，跳转到详情页面进行选课。
- 数据不一致，可能修改了课程信息，而检索库中的数据依旧没有更新。
解决方案：
引入消息队列，当CourseController将数据写入mysql后，需要自己再往MQ发条消息，说"数据更新了"，EsController收到消息去更新索引库。
1.声明队列和交换机
@Configuration public class MqConfig { //交换机名称 public static final String EXCHANGE_NAME = "course.topic"; //新增和修改队列 public static final String INSERT_QUEUE_NAME = "course.insert.queue"; //删除队列 public static final String DELETE_QUEUE_NAME = "course.delete.queue"; //RoutingKey public static final String INSERT_KEY = "course.insert"; public static final String DELETE_KEY = "course.delete"; @Bean public TopicExchange topicExchange(){ return new TopicExchange(EXCHANGE_NAME,true,false); } @Bean public Queue insertQueue(){ return new Queue(INSERT_QUEUE_NAME,true); } @Bean public Queue deleteQueue(){ return new Queue(DELETE_QUEUE_NAME,true); } /** * 绑定队列和交换机关系 */ @Bean public Binding insertQueueBinding(){ return BindingBuilder .bind(insertQueue()) .to(topicExchange()) .with(INSERT_KEY); } @Bean public Binding deleteQueueBinding(){ return BindingBuilder .bind(deleteQueue()) .to(topicExchange()) .with(DELETE_KEY); } 2.发送消息
import org.springframework.amqp.rabbit.core.RabbitTemplate; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.*; import java.security.InvalidParameterException; @RestController @RequestMapping("Course") public class courseController { @Autowired private ICourseService courseService; @Autowired private RabbitTemplate rabbitTemplate; @PostMapping public void saveCourse(@RequestBody Course course){ courseService.save(course); rabbitTemplate.convertAndSend("course.topic","course.insert", course.getId()); } @PutMapping() public void updateById(@RequestBody course course){ if (course.getId() == null) { throw new InvalidParameterException("id不能为空"); } courseService.updateById(course); // 发送MQ消息 rabbitTemplate.convertAndSend("course.topic","course.insert", course.getId()); } @DeleteMapping("/{id}") public void deleteById(@PathVariable("id") Long id) { courseService.removeById(id); // 发送MQ消息 rabbitTemplate.convertAndSend("course.topic", "course.delete", id); } } 3.监听消息队列并进行处理
import org.springframework.amqp.rabbit.annotation.RabbitListener; import org.springframework.stereotype.Component; import javax.annotation.Resource; @Component public class CourseListener { @Resource ICourselService courseService; /** * 监听课程新增或者修改的业务 * id接受一个Long，因为发送过来的是一个Long id */ @RabbitListener(queues = "course.insert.queue“) public void listenCourseInsertAndUpdate(Long id){ CourseService.insertDocById(id); } /** * 监听课程删除业务 */ @RabbitListener(queues = "course.delete.queue“) public void listenCourseDelete(Long id){ CourseService.deleteDocById(id); } } 4.实现上述service功能
新增或修改课程逻辑
- 1）根据id查询课程数据Item
- 2）将Item封装为ItemDoc
- 3）将ItemDoc序列化为JSON
- 4）创建IndexRequest，指定索引库名和id
- 5）准备请求参数，也就是JSON文档
- 6）发送请求
删除课程逻辑
- 1）准备Request对象，因为是删除，这次是DeleteRequest对象。要指定索引库名和id
- 3）发送请求。因为是删除，所以是client.delete()方法
import org.springframework.stereotype.Service; import javax.annotation.Resource; import java.io.IOException; @Service public class CourseService extends ServiceImpl<CourseMapper, Course> implements ICourseService { @Resource RestHighLevelClient client; @Override public void insertDocById(Long id) { try { //0.根据ID查数据，并转为文档类型 Course Course = getById(id); CourseDoc CourseDoc = new CourseDoc(Course); //1.准备request IndexRequest request = new IndexRequest("Course").id(CourseDoc.getId().toString()); //2.准备DSL request.source(JSON.toJSONString(CourseDoc), XContentType.JSON); //3.发送请求 client.index(request,RequestOptions.DEFAULT); } catch (IOException e) { throw new RuntimeException(e); } } @Override public void deleteDocById(Long id) { try { //1.准备request DeleteRequest request = new DeleteRequest("Course",id.toString()); //2.发送请求 client.delete(request,RequestOptions.DEFAULT); } catch (IOException e) { throw new RuntimeException(e); } } } 