Spring框架的隐藏功能？ [英] Hidden features of Spring framework?

问题描述

在看到许多关于编程语言的隐藏特性之后，我想知道Spring事实上框架的隐藏特性。如您所知，Spring文档隐藏了许多功能，并且很乐意分享它。

After seeing many hidden features about programming language, i would like to know hidden features of Spring "de facto" framework. As you know, Spring documentation hides many features and would be nice to share it.

您：您知道Spring框架的哪些隐藏功能？

And you: what hidden feature of Spring framework do you know ?

推荐答案

Spring有一个强大的内置 StringUtils class

Spring has a powerful built-in StringUtils class

请注意以下数组包含一组id

Notice the following array containing a set of id's

String [] idArray = new String [] {"0", "1", "2", "0", "5", "2"} 

并且您想要删除重复的引用。只需这样做

And you want to remove duplicate references. Just do it

idArray = StringUtils.removeDuplicateStrings(idArray);

现在idArray将包含{0，1，2，5} 。

Now idArray will contain {"0", "1", "2", "5"}.

还有更多。

是否可以使用一个Controller类没有在Web应用程序上下文文件中声明它们？

Is it possible to use a Controller class without declare them in web application context file?

是的，只需将@Component放入其声明中（@Controller无法按预期工作）

Yes, just put @Component in its declaration (@Controller does not work as expected)

package br.com.spring.view.controller

@Component
public class PlayerController extends MultiActionController {

    private Service service;

    @Autowired
    public PlayerController(InternalPathMethodNameResolver ipmnr, Service service) {
        this.service = service;

        setMethodNameResolver(ipmnr);
    }

    // mapped to /player/add
    public ModelAndView add(...) {}

    // mapped to /player/remove
    public ModelAndView remove(...) {}

    // mapped to /player/list
    public ModelAndView list(...) {}

}

因此在Web应用程序上下文文件中输入以下内容

So in web application context file put the following

<beans ...>
    <context:component-scan base-package="br.com.spring.view"/>
    <context:annotation-config/>
    <bean class="org.springframework.web.servlet.mvc.support.ControllerClassNameHandlerMapping">
        <property name="order" value="0"/>
        <property name="caseSensitive" value="true"/>
    </bean>
    <bean class="org.springframework.web.servlet.mvc.multiaction.InternalPathMethodNameResolver"/>
</beans>

没有别的

动态表单验证？

使用以下

public class Team {

    private List<Player> playerList;    

}

所以在Team验证器中放

So in Team validator put

@Component
public class TeamValidator implements Validator {

    private PlayerValidator playerValidator;

    @Autowired
    public TeamValidator(PlayerValidator playerValidator) {
        this.playerValidator = playerValidator;
    }

    public boolean supports(Class clazz) {
        return clazz.isAssignableFrom(Team.class);
    }

    public void validate(Object command, Errors errors) {
        Team team = (Team) command;

        // do Team validation

        int index = 0;
        for(Player player: team.getPlayerList()) {
            // Notice code just bellow
            errors.pushNestedPath("playerList[" + index++ + "]");

            ValidationUtils.invokeValidator(playerValidator, player, errors);

            errors.popNestedPath();
        }

    }

}

< hr>

Web表单中的继承？

---

Inheritance in web forms ?

使用ServlerRequestDataBinder和隐藏表单标志

Use ServlerRequestDataBinder along with hidden form flag

public class Command {

    private Parent parent;

}

public class Child extends Parent { ... }

public class AnotherChild extends Parent { ... }

在您的控制器中执行以下操作

And in your controller do the following

public class MyController extends MultiActionController {

    public ModelAndView action(HttpServletRequest request, HttpServletResponse response, Object command) {

        Command command = (Command) command;

        // hidden form flag
        String parentChildType = ServletRequestUtils.getRequiredStringParameter(request, "parentChildType");

        // getApplicationContext().getBean(parentChildType) retrieves a Parent object from a application context file
        ServletRequestDataBinder binder = 
            new ServletRequestDataBinder(getApplicationContext().getBean(parentChildType));

        // populates Parent child object
        binder.bind(request);

        command.setParent((Parent) binder.getTarget());
}

---

Spring有一个内置的在扫描仪类 ClassPathScanningCandidateComponentProvider 。例如，您可以使用它来查找注释。

---

Spring has a built-in scanner class ClassPathScanningCandidateComponentProvider. You can use it to find annotations, for instance.

ClassPathScanningCandidateComponentProvider scanner =
    new ClassPathScanningCandidateComponentProvider(<DO_YOU_WANT_TO_USE_DEFAULT_FILTER>);

scanner.addIncludeFilter(new AnnotationTypeFilter(<TYPE_YOUR_ANNOTATION_HERE>.class));

for (BeanDefinition bd : scanner.findCandidateComponents(<TYPE_YOUR_BASE_PACKAGE_HERE>))
    System.out.println(bd.getBeanClassName());

---

Spring有一个有用的 org.springframework.util.FileCopyUtils 类。您可以使用

public ModelAndView action(...) throws Exception {

    Command command = (Command) command;

    MultiPartFile uploadedFile = command.getFile();

    FileCopyUtils.copy(uploadedFile.getBytes(), new File("destination"));

---

如果使用基于注释的控制器（Spring 2.5） +）或者是普通的MVC Spring控制器，你可以使用WebBindingInitializer来注册全局属性编辑器。类似

---

If you use a annotation based controller (Spring 2.5+) OR plain MVC Spring controller, you can use a WebBindingInitializer to register global property editors. Something like

public class GlobalBindingInitializer implements WebBindingInitializer {

    public void initBinder(WebDataBinder binder, WebRequest request) {
        binder.registerCustomEditor(Date.class, new CustomDateEditor(new SimpleDateFormat("dd/MM/yyyy", true);
    }

}

因此，在您的Web应用程序上下文文件中，声明

So in your web application context file, declare

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter">
    <property name="webBindingInitializer">
        <bean class="GlobalBindingInitializer"/>
    </property>
</bean>

这样任何基于注释的控制器都可以使用在GlobalBindingInitializer中声明的任何属性编辑器。

This way any annotation based controller can use any property editor declared in GlobalBindingInitializer.

依此类推......

And so on...

这篇关于Spring框架的隐藏功能？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！