询问struts 2.1.6 中 action的执行流程？

Question

我理解的一个action类的执行过程是：先 由jsp表单提交后，再调用相应的action类。而在action类中，先类构造函数-->拦截器函数-->execute()执行函数，不知对否？如果上述执行过程正确，下面这个网上经典的例子中，action类的构造函数到底什么时候起作用啊？？？action类：：：package org.apache.struts2.showcase;import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionSupport;
import com.opensymphony.xwork2.Validateable;
import com.opensymphony.xwork2.util.OgnlValueStack;import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.io.File;
public class UITagExample extends ActionSupport implements Validateable {
    
    private static final long serialVersionUID = -94044809860988047L;        
    String name;
    Date birthday;
    String bio;
    String favoriteColor;
    List friends;
    boolean legalAge;
    String state;
    String region;
    File picture;
    String pictureContentType;
    String pictureFileName;
    String favouriteLanguage;
    String favouriteVehicalType = "MotorcycleKey";
    String favouriteVehicalSpecific = "YamahaKey";
    
    List leftSideCartoonCharacters;
    List rightSideCartoonCharacters;
    
    List favouriteLanguages = new ArrayList();
    List vehicalTypeList = new ArrayList();
    Map vehicalSpecificMap = new HashMap();
    
    String thoughts;
    
    public UITagExample() {
        favouriteLanguages.add(new Language("EnglishKey", "English Language"));
        favouriteLanguages.add(new Language("FrenchKey", "French Language"));
        favouriteLanguages.add(new Language("SpanishKey", "Spanish Language"));
        
        VehicalType car = new VehicalType("CarKey", "Car");
        VehicalType motorcycle = new VehicalType("MotorcycleKey", "Motorcycle");
        vehicalTypeList.add(car);
        vehicalTypeList.add(motorcycle);
        
        List cars = new ArrayList();
        cars.add(new VehicalSpecific("MercedesKey", "Mercedes"));
        cars.add(new VehicalSpecific("HondaKey", "Honda"));
        cars.add(new VehicalSpecific("FordKey", "Ford"));
        
        List motorcycles = new ArrayList();
        motorcycles.add(new VehicalSpecific("SuzukiKey", "Suzuki"));
        motorcycles.add(new VehicalSpecific("YamahaKey", "Yamaha"));
        
        vehicalSpecificMap.put(car, cars);
        vehicalSpecificMap.put(motorcycle, motorcycles);
    }   
        
    public List getLeftSideCartoonCharacters() {
        return leftSideCartoonCharacters;
    }
    public void setLeftSideCartoonCharacters(List leftSideCartoonCharacters) {
        this.leftSideCartoonCharacters = leftSideCartoonCharacters;
    }
        
    public List getRightSideCartoonCharacters() {
        return rightSideCartoonCharacters;
    }
    public void setRightSideCartoonCharacters(List rightSideCartoonCharacters) {
        this.rightSideCartoonCharacters = rightSideCartoonCharacters;
    }
        
    public String getFavouriteVehicalType() {
        return favouriteVehicalType;
    }
    
    public void setFavouriteVehicalType(String favouriteVehicalType) {
        this.favouriteVehicalType = favouriteVehicalType;
    }
    
    public String getFavouriteVehicalSpecific() {
        return favouriteVehicalSpecific;
    }
    
    public void setFavouriteVehicalSpecific(String favouriteVehicalSpecific) {
        this.favouriteVehicalSpecific = favouriteVehicalSpecific;
    }
    
    public List getVehicalTypeList() {
        return vehicalTypeList;
    }
    
    public List getVehicalSpecificList() {
        OgnlValueStack stack = ServletActionContext.getValueStack(ServletActionContext.getRequest());
        Object vehicalType = stack.findValue("top");
        if (vehicalType != null && vehicalType instanceof VehicalType) {
            List l = (List) vehicalSpecificMap.get(vehicalType);
            return l;
        }
        return Collections.EMPTY_LIST;
    }
    
    public List getFavouriteLanguages() {
        return favouriteLanguages;
    }    public String execute() throws Exception {
        return SUCCESS;
    }    /**//* Getters and Setters */
           
    public String doSubmit() {
        return SUCCESS;
    }       
    
    // === inner class 
    public static class Language {
        String description;
        String key;
        
        public Language(String key, String description) {
            this.key = key;
            this.description = description;
        }
        
        public String getKey() { 
            return key; 
        }
        public String getDescription() { 
            return description; 
        }
        
    }    
    
    public static class VehicalType {
        String key;
        String description;
        public VehicalType(String key, String description) {
            this.key = key;
            this.description = description;
        }
        
        public String getKey() { return this.key; }
        public String getDescription() { return this.description; }
        
        public boolean equals(Object obj) {
            if (! (obj instanceof VehicalType)) { 
                return false;
            }
            else {
                return key.equals(((VehicalType)obj).getKey());
            }
        }
        
        public int hashCode() {
            return key.hashCode();
        }
    }    
    
    public static class VehicalSpecific {
        String key; 
        String description;
        public VehicalSpecific(String key, String description) {
            this.key = key;
            this.description = description;
        }
        
        public String getKey() { return this.key; }
        public String getDescription() { return this.description; }
        
        public boolean equals(Object obj) {
            if (! (obj instanceof VehicalSpecific)) {
                return false;
            }
            else {
                return key.equals(((VehicalSpecific)obj).getKey());
            }
        }
        
        public int hashCode() {
            return key.hashCode();
        }
    }
}
           

Answer 1

表单文件：：<%@ page contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<html>
<head>
    <title>UI Tags Example</title>
    <s:head/>
</head>
<body><s:actionerror/>
<s:actionmessage/>
<s:fielderror /><s:form action="exampleSubmit" method="post" enctype="multipart/form-data" tooltipConfig="#{'jsTooltipEnabled':'true'}">
    <s:textfield 
            label="Name" 
            name="name"
            tooltip="Enter your Name here" />    <s:datepicker
            tooltip="Select Your Birthday"
            label="Birthday"
            name="birthday" />    <s:textarea
            tooltip="Enter your Biography"
            label="Biograph"
            name="bio"
            cols="20"
            rows="3"/>    <s:select
            tooltip="Choose Your Favourite Color"
            label="Favorite Color"
            list="{'Red', 'Blue', 'Green'}"
            name="favoriteColor"
            emptyOption="true"
            headerKey="None"
            headerValue="None"/>    <s:select
            tooltip="Choose Your Favourite Language"
            label="Favourite Language"
            list="favouriteLanguages"
            name="favouriteLanguage"
            listKey="key"
            listValue="description"
            emptyOption="true"
            headerKey="None"
            headerValue="None"/>    <s:checkboxlist
            tooltip="Choose your Friends"
            label="Friends"
            list="{'Patrick', 'Jason', 'Jay', 'Toby', 'Rene'}"
            name="friends"/>    <s:checkbox
            tooltip="Confirmed that your are Over 18"
            label="Age 18+"
            name="legalAge"/>    <s:doubleselect
            tooltip="Choose Your State"
            label="State"
            name="region" list="{'North', 'South'}"
            value="'South'"
            doubleValue="'Florida'"
            doubleList="top == 'North' ? {'Oregon', 'Washington'} : {'Texas', 'Florida'}" 
            doubleName="state"
            headerKey="-1"
            headerValue="---------- Please Select ----------"
            emptyOption="true" />    <s:doubleselect
            tooltip="Choose your Vehical"
            label="Favourite Vehical"
            name="favouriteVehicalType"
            list="vehicalTypeList"
            listKey="key"
            listValue="description"
            value="'MotorcycleKey'"
            doubleValue="'YamahaKey'"
            doubleList="vehicalSpecificList"
            doubleListKey="key"
            doubleListValue="description"
            doubleName="favouriteVehicalSpecific" headerKey="-1"
            headerValue="---------- Please Select ----------"
            emptyOption="true" />    <s:file
            tooltip="Upload Your Picture"
            label="Picture" 
            name="picture" />
            
    <s:optiontransferselect
            tooltip="Select Your Favourite Cartoon Characters"
            label="Favourite Cartoons Characters"
            name="leftSideCartoonCharacters" 
            leftTitle="Left Title"
            rightTitle="Right Title"
            list="{'Popeye', 'He-Man', 'Spiderman'}" 
            multiple="true"
            headerKey="headerKey"
            headerValue="--- Please Select ---"
            emptyOption="true"
            doubleList="{'Superman', 'Mickey Mouse', 'Donald Duck'}" 
            doubleName="rightSideCartoonCharacters"
            doubleHeaderKey="doubleHeaderKey"
            doubleHeaderValue="--- Please Select ---" 
            doubleEmptyOption="true"
            doubleMultiple="true" />
    
    <s:textarea
            label="Your Thougths"
            name="thoughts" 
            tooltip="Enter your thoughts here" />
            
    <s:submit onclick="alert('aaaa');" />
    <s:reset onclick="alert('bbbb');" />
</s:form>
    
</body>
</html>
struts.xml代码片段<action name="example" class="org.apache.struts2.showcase.UITagExample">
    <result>example.jsp</result>
    <result name="input">example.jsp</result>
</action>例6  

Answer 2

你真牛逼，把structs源码都整上来了
流程大体是form的action调struts.xml对应的
然后看是否有method,没调默认的方法
最后就跳转页面啦

Answer 3

呵呵，我就是想问一下，在action的构造函数中能否对表单的属性进行设置？
例如表单中有一个这样的选择框：
    <s:select 
            tooltip="Choose Your Favourite Language" 
            label="Favourite Language" 
            list="favouriteLanguages" 
            name="favouriteLanguage" 
            listKey="key" 
            listValue="description" 
            emptyOption="true" 
            headerKey="None" 
            headerValue="None"/>
那action的构造函数中，这样设置
        favouriteLanguages.add(new Language("EnglishKey", "English Language")); 
        favouriteLanguages.add(new Language("FrenchKey", "French Language")); 
        favouriteLanguages.add(new Language("SpanishKey", "Spanish Language"));
能对表单选项起作用吗？？这是Max On Java Struts 2.0教程中给出的代码

Answer 4

后台取数据,前台<s:select>遍历？

Answer 5

favouriteLanguages是List对象还是什么？

Answer 6

是的，是List对象，我在2.16的appdoc中也找到这个文件了

Answer 7

前台的表单能取后台action构造出的数据吗？我比较怀疑，也没有执行出来。

Answer 8

而且 s:select本身要求必须有list属性，但list="favouriteLanguages"这样定义也不对啊！表单jsp根本通不过。
list="{'a','b'}"这样写才能通过

Answer 9

struts2里只要set,get,前台就能获取到

Answer 10

set不是从表单中获取数据到action中吗？他是拦截器自动调用的函数吧get是从action中取属性变量的值吗？像beans.

Answer 11

先汗一下
private String username;
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
页面${username}就取到值了

Answer 12

前台查询表单--》set函数--》action中变量--》get函数--》前台显示结果的表单，应该是这样的流程吧？？但从前面的代码中我们看到，action变量中的值 需要直接去作用到 前台查询表单。那这个流程是怎么执行的呢？？？？

Answer 13

没懂，本人中文不好，英文更不好
前台字段名，要和action对上，不知道你是不是这个意思

Answer 14

呵呵，先谢谢楼上诸位了！！归根结底的问题是：假设一个提交表单中一个选择框中多个选项，那么在action中能否设置这多个选项的内容？而不是在表单中直接定义选择框中的多个选项。

Answer 15

我想${username}或者<s:property value="username" />只是获得选择框中用户提交得那个值而已！

Answer 16

因为是先有提交表单，再提交后到action处理啊

Answer 17

在action中设置选择框中多个选项的内容，如何把这个设置作用于（调用该action）的提交表单

Answer 18

你自己先做个登陆练习吧，就这么问，很难回答你
你是说输出吧
循环我一般用foreach

Answer 19

谢谢了！login实例我已经做出来了，现在在学习更复杂的标签！看到上面的代码实例，发出的疑问。

Answer 20

我知道流程是 form表单提交后，根据struts。xml找到相应的action类去处理提交的表单数据。例如选择框（“英语”，“俄语”，“法语”）中的选定的某一项。但action类代码中对选择框多个选项的设置（例如把选择框内容重新设定为“aa”,"bb","cc"）是如何作用于前面提交的表单的？？我就想知道执行的思路。

Answer 21

你想问下拉框list怎么输出吧
 <s:select                list="%{#session.sub}" //存放在httpSession的list集合                listKey="sname" //下拉列表要中列表框要显示的值                 listValue="sname"//下拉列表的值                key="sname"                   id="subject"                   name="subject" //存放在httpSession的值,主要判断是否被选中时候用的               onchange="c(1)"              theme="simple">
           </s:select>
<s:select name="" headerKey="-1" headerValue="请选择" list="list" listKey="uId" listValue="uName"/>list是set,get出来的