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Struts2 + ValueStack + Form Validate

Struts2 + ValueStack + Form Validate

ValueStack

  1. 觀念：

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參考資料：https://blog.csdn.net/qq_44757034/article/details/106838688

  1. 範例：

Action

@Namespace("/")
@Results(value = { 
    @Result(name = "hello", location = "/WEB-INF/jsp/hello.jsp") ,
    @Result(name = "goodbye", location = "/WEB-INF/jsp/goodbye.jsp") 
})
@Data
public class HelloAction extends ActionSupport {

    private String paramName;

    @Action(value = "hello")
    public String hello() {

        // Root
        ActionContext.getContext().getValueStack().set("name", "root-ABC");

        // Request
        ServletActionContext.getRequest().setAttribute("name", "request-ABC");

        // Request Session
        ServletActionContext.getRequest().getSession().setAttribute("name", "session-ABC");

        // Servlet Context
        ServletActionContext.getServletContext().setAttribute("name", "servlet context-ABC");

        return "hello";
    }
}

JSP

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags"%>
Action 屬性：<s:property value="paramName" />
<br>
請求參數：<s:property value="#parameters.paramName" />
<br>
請求屬性：<s:property value="#request.name" />
<br>
請求屬性：<s:property value="#attr.name" />
<br>
請求會話屬性：<s:property value="#session.name" />
<br>
上下文屬性：<s:property value="#application.name" />

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請求參數

  1. Action：只要有 @Data 標註，S2 會自動依照請求參數的名稱，對應到 Action 屬性名稱相符的屬性。
@Namespace("/")
@Results(value = { 
    @Result(name = "hello", location = "/WEB-INF/jsp/hello.jsp") ,
    @Result(name = "goodbye", location = "/WEB-INF/jsp/goodbye.jsp") 
})
@Data
public class HelloAction extends ActionSupport {

    private String paramName;

    @Action(value = "hello")
    public String hello() {
        System.out.println(paramName);
        return "hello";
    }
}
  1. JSP：
<%@ taglib prefix="s" uri="/struts-tags"%>
<s:property value="paramName" />
  1. Test： http://localhost:8080/Struts2Beginner/hello?paramName=ABC

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Validate Form

只要在 Action 中 新增一個 validate 方法，把要驗證的邏輯寫進去。這樣每一次 Action 的請求，都會先經過 validate 方法，如果有錯誤，則將訊息透過 addFieldError 這種紀錄下來。如果沒有錯誤，則會接著呼叫 execute 方法，進而來到 View 的 JSP。

1、Action

import org.apache.commons.lang3.StringUtils;
import org.apache.commons.validator.routines.EmailValidator;
import org.apache.struts2.convention.annotation.Action;
import org.apache.struts2.convention.annotation.Namespace;
import org.apache.struts2.convention.annotation.Result;
import org.apache.struts2.convention.annotation.Results;

import com.example.struts.model.Person;
import com.opensymphony.xwork2.ActionSupport;

import lombok.Data;

@Data
@Namespace("/")
@Action(value = "register")
@Results(value = { 
        @Result(name = "success", location = "/thankyou.jsp"),
        @Result(name = "input", location = "/register.jsp"),}
)
public class RegisterAction extends ActionSupport {

    private Person person;

    public String execute() throws Exception {
        return SUCCESS;
    }

    public void validate() {

        if (person == null || person.getFirstName().length() == 0) {
            addFieldError("person.firstName", "First name is required.");
        }

        if (person == null || person.getEmail().length() == 0) {
            addFieldError("person.email", "Email is required.");
        }

        if (person != null && !StringUtils.isEmpty(person.getEmail())) {
            boolean isValid = EmailValidator.getInstance().isValid(person.getEmail());
            if(!isValid) {
                addFieldError("person.email", "Email is invalided.");
            }
        }

        if (person == null || person.getAge() < 18) {
            addFieldError("person.age", "Age is required and must be 18 or older");
        }
    }
}
  1. JSP：、、

(不加入MDB)

<%@ taglib prefix="s" uri="/struts-tags"%>
<h1>Registration Form</h1>
<s:form action="register">
    <s:textfield name="person.firstName" label="First Name" />
    <s:textfield name="person.lastName" label="Last Name" />
    <s:textfield name="person.email" label="Email" />
    <s:textfield name="person.age" label="Age" type="number" />
    <s:submit value="Register" />
</s:form>
<s:fielderror fieldName="person.firstName" cssClass="error" />
<s:fielderror fieldName="person.lastName" cssClass="error" />
<s:fielderror fieldName="person.email" cssClass="error" />
<s:fielderror fieldName="person.age" cssClass="error" />

(加入 MDB)

<%@ taglib prefix="s" uri="/struts-tags"%>
<div class="d-flex justify-content-center">
    <div style="width: 300px;">
        <h2>Registration Form</h2>
        <s:form action="register" theme="simple">
            <s:fielderror fieldName="person.firstName" cssClass="error small-red-text"/>
            <div class="form-outline my-2">
                <s:textfield name="person.firstName" cssClass="form-control" id="firstName" required="true"/>
                <label class="form-label" for="firstName" style="">First Name</label>
            </div>

            <s:fielderror fieldName="person.lastName" cssClass="error small-red-text"/>
            <div class="form-outline my-2">
                <s:textfield name="person.lastName" cssClass="form-control" id="lastName" required="true"/>
                <label class="form-label"  for="lastName" style="">Last Name</label>
            </div>

            <s:fielderror fieldName="person.email" cssClass="error small-red-text"/>
            <div class="form-outline my-2">
                <s:textfield name="person.email" cssClass="form-control" id="email" type="email"/>
                <label class="form-label" for="email" style="">Email</label>
            </div>

            <s:fielderror fieldName="person.age" cssClass="error small-red-text"/>
            <div class="form-outline my-2">
                <s:textfield name="person.age" cssClass="form-control" id="age" type="number" />
                <label class="form-label" for="age" style="">Age</label>
            </div>
            <button type="submit" class="btn btn-primary btn-block my-2">Register</button>
        </s:form>
    </div>
</div>

CSS

.error {
    color: red;
}

.small-red-text {
    font-size: 11px;
    text-align: left;
    margin-left: 10px !important;
}

ul.error {
    list-style-type: none;
    padding-left: 0;
    margin: 0%;

}
  1. Test：

(1) 第一次不用顯示錯誤訊息，所以直接存取該JSP

http://localhost:8080/Struts2Beginner/register.jsp

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(2) 直接按下提交，畫面會顯示錯誤訊息。

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(3) 欄位接輸入後，且通過檢查後，才會顯示正確頁面。

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