Spring 3 @RequestMapping 应该自动绑定请求参数吗？
自动绑定请求参数似乎是默认行为，但我找不到很多关于它的文档。这是我的例子：
<form:form modelAttribute="test" action="testsubmit.do" method="POST">
Name: <form:input path="name" />
Nested Name: <form:input path="test.nestedName"/>
<input type="submit"/>
public class Test {
public String name;
public String name2;
public TestNested test;
...
public class TestNested {
public String nestedName;
...
现在使用我的映射：
@RequestMapping(value = "/testsubmit")
public String testSubmit(Test test){
...
test 对象正在绑定表单值，包括嵌套值。在我看来，这似乎是预期的行为，但我对 @ModelAttribute 注释及其与指定为映射方法参数的对象的使用有点困惑。
15.3.2.8使用 @ModelAttribute 提供模型数据的链接表示：
当您将其放在方法参数上时，
@ModelAttribute会将模型属性映射到特定的带注释的方法参数（请参阅下面的processSubmit()方法）。这就是控制器如何获取对保存表单中输入的数据的对象的引用。
当我在加载时将对象 test 绑定到表单时，我将一个值设置为 name2。
@RequestMapping(value = "/test")
public String test(Model model) {
Test test = new Test();
test.setName2("test name2");
model.addAttribute("test", test);
return "test";
}
当我用 @ModelAttribute("test") 注释 test 参数时，这不会在 submit 方法上传递：
@RequestMapping(value = "/testsubmit")
public String testSubmit(@ModelAttribute("test") Test test) {
...
这是预期的对我来说，因为 name2 未指定为表单字段/请求参数，但这并不能帮助我理解 @ModelAttribute("test") 用法的要点。有人能为我解释一下吗？
Auto-binding of request params seems like default behaviour, but I can't find a lot of documentation on it. Here is my example:
<form:form modelAttribute="test" action="testsubmit.do" method="POST">
Name: <form:input path="name" />
Nested Name: <form:input path="test.nestedName"/>
<input type="submit"/>
public class Test {
public String name;
public String name2;
public TestNested test;
...
public class TestNested {
public String nestedName;
...
Now with my mapping:
@RequestMapping(value = "/testsubmit")
public String testSubmit(Test test){
...
The test object is binding the form values including the nested value. This seems to me like expected behavior, but I am a bit confused by the @ModelAttribute annotation and its use with respect to objects specified as mapped method parameters.
15.3.2.8 Providing a link to data from the model with @ModelAttribute says:
When you place it on a method parameter,
@ModelAttributemaps a model attribute to the specific, annotated method parameter (see theprocessSubmit()method below). This is how the controller gets a reference to the object holding the data entered in the form.
When I bind the object test to the form on load, I set a value to name2.
@RequestMapping(value = "/test")
public String test(Model model) {
Test test = new Test();
test.setName2("test name2");
model.addAttribute("test", test);
return "test";
}
This doesn't get passed through on the submit method when I annotate the test parameter with @ModelAttribute("test"):
@RequestMapping(value = "/testsubmit")
public String testSubmit(@ModelAttribute("test") Test test) {
...
This is expected to me as name2 was not specified as a form field/request param, but it doesn't help me understand the point of the @ModelAttribute("test") usage. Can anyone shed some light on this for me?
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@ModelAttribute 只是让您为模型中的对象指定不同的名称/键。如果您不使用它，Spring 将根据对象的类自动分配一个名称，例如，在“Test”类的情况下为“test”。使用@ModelAttribute，您可以通过指定“@ModelAttribute("whatever")”将模型中对象的名称/键更改为“whatever”。
@ModelAttribute just lets you specify a different name/key for your object in the model. If you don't use it, Spring will automatically assign a name based on the object's class, e.g. "test" in the case of your "Test" class. With @ModelAttribute you could change the name/key of your object in the model to, for example, "whatever" by specifying "@ModelAttribute("whatever")".