在Spring MVC中return ModelAndView和return String有什么区别? [英] What is the difference between return ModelAndView and return String in Spring MVC?

问题描述

我想知道ModelAndView和String之间的区别.

I want to know the different between ModelAndView and String.

@RequestMapping(value="/")
    public ModelAndView mainPage() {
        return new ModelAndView("home");
}

第二段代码是关于返回String的:

and the second piece of code is about returning String:

@RequestMapping(value="/")
    public String mainPage() {
        return "home";
}

推荐答案

您可以从控制器返回很多东西，Spring会自动尝试从那里推断出要做什么.

You can return many things from a controller, and Spring will automatically try to deduce what to do from there.

当返回ModelAndView时，所有需要从控制器传递的信息都嵌入其中.没有惊喜.

When you return a ModelAndView all information that needs to be passed from the controller is embedded inside it. No suprise there.

如果返回String，它将假定这是要使用的视图的名称.它将把它包装在一个ModelAndView对象中，该对象具有字符串作为视图，并且还嵌入了现有模型.

If you return a String, it will assume that this is the name of the view to use. It will wrap this in a ModelAndView object with the string as the view and the existing model embedded as well.

Spring在返回类型以及参数类型上都有很多魔力". 这样一来，您便可以以更直观的方式编写代码，即以下两个示例相同:

Spring does a lot of 'magic' on the return types, but also on the parameter types. This allows you to write code in a style that is more intuitive for you, i.e. the following two examples are the same:

@RequestMapping(value="/")
public ModelAndView mainPage() {
    Model m = new Model();
    m.put("key", "value");
    return new ModelAndView(m,"main");
}

和

@RequestMapping(value="/")
public String mainPage(Model m) {
    m.put("key", "value");
    return "main";
}

第二个变体稍微冗长一些，更易于单独测试.传入的模型将为空模型(除非从其他控制器转发).

This second variant is a little less verbose and easier to test separately. The model passed in will be an empty model (unless forwarded from some other controller).

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