类型转换

Posted 2020-08-14 晨曦-荒微凉

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struts2的自定义类型转换机制为复杂类型的输入输出处理提供了便捷.struts2已经为我们提供了几乎所有的primitive类型以及常用类型(如Date)的类型转换器,我们也可以为我们自定义类添加自定义类型转化器.

下面来看一下自定义类型转换

先定义实体类

package entity;

import java.util.Date;

public class User {
    private String name;//姓名
    private Integer age;//年龄
    private Date birthday;//出生日期
    public String getName() {
        return name;
    }
    public Integer getAge() {
        return age;
    }
    public Date getBirthday() {
        return birthday;
    }
    public void setName(String name) {
        this.name = name;
    }
    public void setAge(Integer age) {
        this.age = age;
    }
    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }
    
    
}

接下来我们创建一个AddUserAction

package action;



import com.opensymphony.xwork2.ActionSupport;

import entity.User;



public class AddUserAction extends ActionSupport  {
    //调用实体类
    private User user;
    public String execute() throws Exception{
        //在此我们就用出生日期来实现一下
        System.out.println(user.getBirthday());
        return SUCCESS;
        
    }


    public User getUser() {
        return user;
    }


    public void setUser(User user) {
        this.user = user;
    }
    

}

接下来我们创建出自己的类型转换器

package converter;

import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Map;

import org.apache.struts2.util.StrutsTypeConverter;

import com.opensymphony.xwork2.conversion.TypeConversionException;

public class Dateconverter extends StrutsTypeConverter{
       //将前台获取到的值转换成Date类型
       private final DateFormat[] dfs={
               new SimpleDateFormat("yyyy/MM/dd"),
               new SimpleDateFormat("yyyy年MM月dd日"),
               new SimpleDateFormat("yyyy-MM-dd"),
               new SimpleDateFormat("yyyy.MM.dd"),
               new SimpleDateFormat("yyyyMMdd"),
               new SimpleDateFormat("MM/dd/yyyy"),
       };

    
    /**
     * String类转换成特定的类
     * 用于前台传值到后台
     */
    @Override                //context里的map对象     前台创来的值                
    public Object convertFromString(Map context, String[] values, Class toType) {
        String value=(String)values[0];
        for (int i = 0; i < dfs.length; i++) {
            try {
                return dfs[i].parse(value);
            } catch (ParseException e) {
                // TODO Auto-generated catch block
                continue;
            }
        }
        throw new TypeConversionException();
    }
    /**
     * 前台取值
     * 
     */
    @Override
    public String convertToString(Map context, Object obj) {
        
        
        return new SimpleDateFormat("yyyy-MM-dd").format(obj);
    }

}

创建AddUserAction-conversion.properties关联关系

当我们用到user.birthday属性时会自动调用converter.Dateconverter.java类型转换器

接下来写配置adduser.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
    <constant name="struts.devMode" value="true"></constant>
    <package name="default" namespace="/" extends="struts-default">
        <action name="AddUser" class="action.AddUserAction">
            <result name="success">/success.jsp</result>
        </action>
    </package>
    
</struts>

接下来配置struts.xml文件并引用adduser.xml文件

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
"http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
<constant name="struts.ui.theme" value="simple"></constant>
<constant name="struts.devMode" value="false"></constant>
<constant name="struts.enable.DynamicMethodInvoaction" value="true"></constant>
<package name="main" namespace="/" extends="struts-default">

</package>
<include file="action/adduser.xml"></include>
</struts>

接下来编写输入与展示页面

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP \'index.jsp\' starting page</title>
    
  </head>
  
  <body>
  <s:fielderror/>
   <form action="AddUser" method="post">
       姓名:<input type="text" name="user.name"/><br/>
       年龄:<input type="text" name="user.age"/><br/>
       出生日期:<input type="text" name="user.birthday"/><br/>
       <input type="submit" value="提交"/>
   </form>
  </body>
</html>

展示页面

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP \'success.jsp\' starting page</title>
   
  </head>
  
  <body>
    <s:date name="user.birthday"  format="yyyy-MM-dd"/>
  </body>
</html>

效果展示