Details that need to be paid attention to when java receives form submitted parameters through beans

This article mainly introduces the points to note when using beans in SpringMVC to receive parameters submitted by form forms, and has a good reference value. Let's take a look at it with the editor

This is the summary experience of the predecessors in recording form data received by SpringMVC:

SpringMVC receives page form parameters

springmvcRequest parametersSeveral methods of obtaining

The following are the details and points of attention that I discovered when using it. The predecessors did not record the details and points of attention:

Use When the bean receives the parameters submitted by the form form, the pojo must contain a default (i.e. empty) constructor . At the same time, the variable that needs to be set in the bean must have a setter method.

Note: The following codes are all sample codes. They are not actual codes run by me. Please add them by yourself.

For example: I have a bean class called User with variables username and password. At the same time, the content submitted by the form is:

<form action="save-user-info" method="post">
 <span>帐号：</span><input type="text" name="username"><br>
 <span>密码：</span><input type="text" name="password"><br>
 <input type="submit" value="保存">
</form>

Then, the User.java file must have

public User() {}

public void setUsername(String username) {
  this.username = username;
}

public void setPassword(String password) {
  this.password = password;
}

At this time, I can successfully receive the parameters in the Controller and generate the corresponding beanObject

@RequestMapping(value="/save-user-info")
public String saveUser(SsbiUser user) {
  System.out.println(user.toString());
  return "user-info";
}

Through some tests, I understand this process as, After the front desk submits a form containing User data, after the background receives the parameters, it will first Generate a User object that does not contain any parameters, and then set the corresponding value to this empty object through the setter method, and finally get the User object we need .

Instead of what I thought at first, the background receives the parameters and directly calls the corresponding User(username, password)Construction methodGenerate required object.

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