为什么从非bean类的方法调用可缓存方法时@Cacheable不起作用 [英] Why @Cacheable not working when calling cacheable method from method of non bean class

问题描述

我突然发现，当我从非bean类内部的方法调用可缓存方法时，@ Cacheable无法正常工作.

I have suddently found that @Cacheable not worked when i call cacheable method from method inside not bean class.

请在我的代码下面找到并帮助我解决问题或错过的事情.

Please find below my code and help me what is issue or something i miss.

EmployeeDAO.java

@Component("employeeDAO")
public class EmployeeDAO {
private static EmployeeDAO staticEmployeeDAO;

public static EmployeeDAO getInstance(){
    return staticEmployeeDAO;
}

@PostConstruct
void initStatic(){
    staticEmployeeDAO = this;
}

@Cacheable(value = "employeeCache")
public List<Employee> getEmployees() {
    Random random = new Random();
    int randomid = random.nextInt(9999);
    System.out.println("*** Creating a list of employees and returning the list ***");
    List<Employee> employees = new ArrayList<Employee>(5);
    employees.add(new Employee(randomid, "Ben", "Architect"));
    employees.add(new Employee(randomid + 1, "Harley", "Programmer"));
    employees.add(new Employee(randomid + 2, "Peter", "BusinessAnalyst"));
    employees.add(new Employee(randomid + 3, "Sasi", "Manager"));
    employees.add(new Employee(randomid + 4, "Abhi", "Designer"));
    return employees;
}    

MyThread.java

class MyThread{
public void run(){
    //How to get Employee data. ?????
}
}    

UtilityClass.java

public class UtilityClass {
public static void getEmployee(){
    EmployeeDAO.getInstance().getEmployees();
}
}    

Main.java

public class Main {


public static void main(String[] args) {

    ApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
    EmployeeDAO dao = (EmployeeDAO)context.getBean("employeeDAO");

    System.out.println("1'st call");
    dao.getEmployees();
    System.out.println("2'nd call");
    dao.getEmployees();
    System.out.println("Call cache method using utility class");

    System.out.println("1'st call on utilityclass");
    UtilityClass.getEmployee();
    System.out.println("2'nd call on utilityclass");
    UtilityClass.getEmployee();
}
}    

输出:

1'st call
*** Creating a list of employees and returning the list ***
2'nd call
Call cache method using utility class
1'st call on utilityclass
*** Creating a list of employees and returning the list ***
2'nd call on utilityclass
*** Creating a list of employees and returning the list ***  

有人可以帮助我吗?

推荐答案

Spring使用代理来应用AOP，但是代理是在构造bean之后创建的.

Spring uses proxies to apply AOP, however proxies are created after a bean has been constructed.

在带有@PostConstruct注释的方法中，您正在设置对this的引用，但是此时是Bean的未代理实例.您确实需要代理实例.

In your @PostConstruct annotated method you are setting a reference to this however at that moment that is the unproxied instance of the bean. You really need the proxied instance.

我还要指出，您的解决方案是非常糟糕的解决方案，不会通过我的质量检查.但这是恕我直言.

I would also note that your solution is imho a very bad one and wouldn't pass my QA check. but that is imho.

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