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Spring在Runtime中向服务上下文添加一些bean

javabeans initialization servlets spring java

ÐÐ²Ð°Ð½ ÐÐ¾Ð»ÑÐ½ÑÑÐº · 技术社区 · 9 年前

我正在创建spring dispatcherServlet,并将其servlet上下文设置为:

import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.servlet.DispatcherServlet;


import javax.servlet.ServletConfig;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import java.io.IOException;
import java.util.*;

public class MyDispatcherBean implements InitializingBean {


    @Autowired
    private ApplicationContext applicationContext;

    private DispatcherServlet dispatcherServlet;

    private final String someContext = "some.xml";

    private ServletContext servletContext;


    public void execute(/* Do some code..*/) throws IOException {

        /*
        Do some code..
        */
        try {
            dispatcherServlet.service(/* ...*/);
        } catch (ServletException e) {

        }

    }

    public WebApplicationContext getServiceContext() {
        return dispatcherServlet.getWebApplicationContext();
    }
    public void afterPropertiesSet() throws Exception {

        dispatcherServlet = new DispatcherServlet() {

            private static final long serialVersionUID = -7492692694742330997L;

            @Override
            protected WebApplicationContext initWebApplicationContext() {
                WebApplicationContext wac = createWebApplicationContext(applicationContext);
                if (wac == null) {
                    wac = super.initWebApplicationContext();
                }
                return wac;
            }

        };

        dispatcherServlet.setContextConfigLocation(someContext);
        dispatcherServlet.init(new DelegatingServletConfig());
    }

    private class DelegatingServletConfig implements ServletConfig {

        public String getServletName() {
            return "myDispatcher";
        }

        public ServletContext getServletContext() {
            return MyDispatcherBean.this.servletContext;
        }

        public String getInitParameter(String paramName) {
            return null;
        }

        public Enumeration<String> getInitParameterNames() {
            return Collections.enumeration(new HashSet<String>());
        }
    }

}

我这样创建这个bean:

<bean id="myDispatcher" class="some.package.MyDispatcherBean " />

然后,在我的代码中的任何位置都可以存在任意数量的bean,这些bean的代码可以获取“myDispatcher”bean,并在Runtime中将一些bean添加到DispatcherServlet的servlet上下文中:

public class ContextAdder implements InitializingBean {


    @Autowired
    private ApplicationContext applicationContext;


    public String classPathToContext;

    public void afterPropertiesSet() throws Exception {


        DispatcherServlet dispatcherServlet = applicationContext.getBean("myDispatcher",DispatcherServlet.class);
        XmlWebApplicationContext webApplicationContext = (XmlWebApplicationContext) dispatcherServlet.getWebApplicationContext();
        XmlBeanDefinitionReader xmlReader = new XmlBeanDefinitionReader((DefaultListableBeanFactory) webApplicationContext.getBeanFactory());
        xmlReader.loadBeanDefinitions(new ClassPathResource(classPathToContext));

    }

    public ApplicationContext getApplicationContext() {
        return applicationContext;
    }

    public void setApplicationContext(ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }

    public String getClassPathToContext() {
        return classPathToContext;
    }

    public void setClassPathToContext(String classPathToContext) {
        this.classPathToContext = classPathToContext;
    }
}

这些bean是这样创建的:

<bean id="adder1" class="stargate.sg_1.ContextAdder" depends-on="myDispatcher">
        <property name="classPathToContext" value="Optimus.xml" />
</bean>

<bean id="adder2" class="stargate.atlantida.ContextAdder" depends-on="myDispatcher">
        <property name="classPathToContext" value="StarShip.xml" />
</bean>

最后,我期望行为:每个ContextAdderbean将新bean添加到myDispatcherbean中dispatcherServlet的servlet上下文中。

但我害怕一些时刻:

这只是这个问题的一个决定吗?
这是最好的吗?
每次我向DispatcherServlet的servletContext添加新bean时,它会调用servletContext甚至ApplicationContext的刷新吗?如果是真的,它会影响性能吗?
所有生命周期都正确吗?

1 回复 | 直到 9 年前

Ian Mc 9 年前

我相信有更好的方法,但将由您决定。

使用您的方法(实现InitializingBean),您将在bean定义阶段完成后调用bean创建代码之后豆子正在构建中。您的bean定义阶段非常简单(只需创建“myDispatcher”)。

我建议您在bean定义阶段创建/加载所有bean定义。实现这一点的一种方法是挂接到BeanFactory后处理器(实现BeanFacctoryPostProcessor)。在这个阶段,Spring允许您修改现有的bean定义,更重要的是,您可以添加更多bean定义。现在,当您离开这个阶段时,将在一个阶段中创建所有bean。这种方法非常自然:创建bean定义=>bean被创建并连接=>完成。

public class ContextAdder implements BeanFactoryPostProcessor {

@Override
public void postProcessBeanFactory(ConfigurableListableBeanFactory factory)
        throws BeansException {

    XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader((BeanDefinitionRegistry)factory);

    // I)  LOAD BY PATTERN MATCHING
    //PathMatchingResourcePatternResolver resourceResolver = new PathMatchingResourcePatternResolver(factory.getBeanClassLoader());
    //for (Resource resource : resourceResolver.getResources("com/.../*.xml"))
    //reader.loadBeanDefinitions(resource);

    // II)  LOAD A SINGLE FILE AT A TIME
    reader.loadBeanDefinitions(new ClassPathResource("com/../Optimus.xml""));
    .....
}

也许你可以根据你的独特需求采用这个概念。