Model Attribute 和 commandName 属性在春季表单标签中的区别？

在 Spring3中，我在 jsp 的表单标记中看到了两个不同的属性

<form:form method="post" modelAttribute="login">

其中属性 model Attribute 是用于填充表单的表单对象的名称。我在发布表单时使用它，在控制器中使用 @ModelAttribute捕获值，调用验证器，应用业务逻辑。这里一切都很好。现在

<form:form method="post" commandName="login">

这个属性的期望是什么，它是否也是一个我们要填充其属性的表单对象？

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I had the same question a while ago, I can't remember the exact differences but from research I ascertained that commandName was the old way of doing it and in new applications you should be using modelAttribute

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最佳答案

If you look at the source code of FormTag (4.3.x) which backs your <form> element, you'll notice this

/**
* Set the name of the form attribute in the model.
* <p>May be a runtime expression.
*/
public void setModelAttribute(String modelAttribute) {
this.modelAttribute = modelAttribute;
}


/**
* Get the name of the form attribute in the model.
*/
protected String getModelAttribute() {
return this.modelAttribute;
}


/**
* Set the name of the form attribute in the model.
* <p>May be a runtime expression.
* @see #setModelAttribute
*/
public void setCommandName(String commandName) {
this.modelAttribute = commandName;
}


/**
* Get the name of the form attribute in the model.
* @see #getModelAttribute
*/
protected String getCommandName() {
return this.modelAttribute;
}

They are both referring to the same field, thus having same effect.

But, as the field name indicates, modelAttribute should be preferred, as others have also pointed out.

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OLD WAY = commandName 

...
<spring:url value="/manage/add.do" var="action" />
<form:form action="${action}" commandName="employee">
<div>
<table>
....

NEW WAY = modelAttribute

..
<spring:url value="/manage/add.do" var="action" />
<form:form action="${action}" modelAttribute="employee">
<div>
<table>
..
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In xml based config, we will use command class to pass an object between controller and views. Now in annotation we are using modelattribute.

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commandName = name of a variable in the request scope or session scope that contains the information about this form,or this is model for this view. Tt should be a been.


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