[英]Spring cache using @Cacheable not working on startup @PostConstruct
[英]Spring boot cache not working with @PostConstruct or @AfterPropertiesSet
當我的應用程序啟動時,我嘗試用數據初始化我的緩存,但這不起作用。 我的代碼:
springBoot應用程序
package com.r2b.springcache;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.concurrent.ConcurrentMapCacheManager;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
@ComponentScan("com.r2b")
@SpringBootApplication
@EnableCaching
public class SpringCacheApplication {
public static void main(String[] args) {
SpringApplication.run(SpringCacheApplication.class, args);
}
@Bean
public CacheManager cacheManager() {
return new ConcurrentMapCacheManager("student");
}
}
學生
package com.r2b.model;
public class Student {
String id;
String name;
String clz;
public Student(String id, String name, String clz) {
super();
this.id = id;
this.name = name;
this.clz = clz;
}
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 getClz() {
return clz;
}
public void setClz(String clz) {
this.clz = clz;
}
//Setters and getters
}
學生服務
package com.r2b.service;
import org.springframework.cache.annotation.Cacheable;
import org.springframework.stereotype.Service;
import com.r2b.model.Student;
@Service
public class StudentService
{
@Cacheable("student")
public Student getStudentByID(String id)
{
try
{
System.out.println("Going to sleep for 5 Secs.. to simulate backend call.");
Thread.sleep(1000*5);
}
catch (InterruptedException e)
{
e.printStackTrace();
}
return new Student(id,"Sajal" ,"V");
}
}
學生控制器
package com.r2b.controller;
import javax.annotation.PostConstruct;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import com.r2b.model.Student;
import com.r2b.service.StudentService;
@RestController
public class StudentController
{
@Autowired
StudentService studentService;
@PostConstruct
public void init() {
studentService.getStudentByID("1");
}
@GetMapping("/student/{id}")
public Student findStudentById(@PathVariable String id)
{
System.out.println("Searching by ID : " + id);
return studentService.getStudentByID(id);
}
}
pom.xml
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.r2b</groupId>
<artifactId>spring-cache</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>spring-cache</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.0.5.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
第一次訪問http://localhost:8080/student/1時,緩存沒有激活,響應時間超過5秒,但是刷新時緩存響應,請求耗時幾毫秒! 盡管我在 postConstruct 中調用了緩存方法,但我嘗試使用 @AfterPropertiesSet 但它也不起作用!
任何的想法 ?
謝謝
答案很簡單,但我花了將近一天的時間才發現用@Cacheable 修飾的方法在@PostConstruct 中沒有效果
只需將您的@PostConstruct替換為@EventListener (ApplicationReadyEvent.class)
@EventListener(ApplicationReadyEvent.class)
public void init() {
studentService.getStudentByID("1");
}
注意如果從用@PostConstruct或EventListener (ApplicationReadyEvent.class) 事件修飾的方法拋出異常,您的應用程序將退出...
這不起作用,因為代理尚未初始化。 這實際上記錄在用戶指南中
在代理模式(默認)下,只攔截通過代理進入的外部方法調用。 這意味着自調用(實際上,目標對象中的一個方法調用目標對象的另一個方法)不會在運行時導致實際緩存,即使被調用的方法被標記為@Cacheable。 在這種情況下考慮使用 aspectj 模式。 此外,必須完全初始化代理才能提供預期的行為,因此您不應在初始化代碼(即@PostConstruct)中依賴此功能。
這正是你在這里所做的。 緩存應該盡可能透明,所以在啟動時預加載緩存對我來說有點奇怪(並增加啟動時間)。
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