Spring bean属性持久存在

Question

I have a plain POJO being autowired in Spring whose properties appear to persist.

I find that the happy path is OK - Set bean properties and return then, however when I'm not on the happy path and I no longer wish to set a property (in this case responseCode), I find it is still set to the previous value (when a call was successful).

I would like this value to not be set and be equal to what I have currently specified in the model.

I have the following POJO Prototype bean

package com.uk.jacob.model;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component
@Scope("prototype")
public class Website {
    public String url;
    public boolean response;
    public int responseCode = 0;
}

I am setting it's information within a service class

package com.uk.jacob.service;

import java.net.HttpURLConnection;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import com.uk.jacob.adapter.HttpAdapter;
import com.uk.jacob.model.Website;

@Component
public class PingerService {

    @Autowired
    HttpAdapter httpAdapter;

    @Autowired
    Website website;

    public Website ping(String urlToPing) { 
        website.url = urlToPing;

        try {
            HttpURLConnection connection = httpAdapter.createHttpURLConnection(urlToPing);

            website.response = true;
            website.responseCode = connection.getResponseCode();
        } catch (Exception e) {
            website.response = false;
        }

        return website;
    }
}

Which is called from a RestController

package com.uk.jacob.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

import com.uk.jacob.model.Website;
import com.uk.jacob.service.PingerService;

@RestController
@RequestMapping("api/v1/")
public class PingController {

    @Autowired
    PingerService pingerService;

    @RequestMapping(value = "ping", method = RequestMethod.GET)
    public Website getPing(@RequestParam String url){
        return pingerService.ping(url);
    }

}

Answer 1

The fact that your Website bean is @Scope("prototype") means that every time that it gets injected as a dependency in another bean upon this bean's creation, a new instance gets created and injected. In this case PingerService gets a new instance of Website . If say Website is also injected on another bean called Website2 then a different (new) instance gets injected.

If your anticipation is Website to be new upon each invocation within Website then this cannot be done simply with the prototype annotation. You'll need to expose the context and invoke ApplicationContext#getBean("website") .

Answer 2

For your use case, I understand that you need a fresh instance of Website bean for every request.

Use @Scope("request").

Prototype scope on the other hand means it will be creating a separate instance for every Autowiring of Website it sees everywhere. For example, PingerService will have its own Website bean and won't be shared on other classes with the same Autowiring but its values will persist across http requests on PingerService.