java struts2入门学习---中文验证、对错误消息的分离、结果(result)类型细节配置

一、需求

利用struts2实现中文验证并对错误消息的抽离。

详细需求：用户登录－－》不填写用户名－－》页面跳转到用户登录页面,提示用户名必填（以英文和中文两种方式提示）－－》填写英文用户名－－》页面提示用户名必须填写为英文－－－》填写中文用户名－－－》页面跳转到登录成功页面。

二、效果图

1、英文提示

2、中文提示

三、代码分析

result.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@ taglib uri="/struts-tags" prefix="s"  %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

    <s:form action="ResultAction" enctype="multipart/form-data" method="POST">

        <s:textfield label="用户名" name="username"/>

        <s:submit value="提交"/>

    </s:form>

</body>

</html>

result_success.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"

    pageEncoding="UTF-8"%>

<%@ taglib uri="/struts-tags" prefix="s"  %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

<title>Insert title here</title>

</head>

<body>

　　　恭喜，登录成功！

    <hr>

    用户名:<s:property value="username"/>

</body>

</html>

ResultAction.java

package result;

import com.opensymphony.xwork2.ActionSupport;

public class ResultAction extends ActionSupport {

    private static final long serialVersionUID = 7340087601249007671L;

    private String username;

    public String getUsername() {

        return username;

    }

    public void setUsername(String username) {

        this.username = username;

    }

    public void validate() {

        if (username != null && username.trim().length() > 0) {

            if (username.matches("[\u4e00-\ufa29]+")) {

            } else {

                // this.addFieldError("username", "用户名必须为中文");

                this.addFieldError("username", this.getText("result.username.mustchinese"));

            }

        } else {

            this.addFieldError("username", this.getText("result.username.required"));

            // this.addFieldError("username", "用户名必填！");

        }

    }

    public String execute() throws Exception {

        return SUCCESS;

    }

}

struts.xml

<?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>

    <!--<include file="config/upload.xml"></include>-->

    <!-- 加载其他配置文件 -->

    <!-- <include file="config/upload-interceptor.xml"></include> -->

    <!-- 加载属性文件－国际化 -->

    <constant name="struts.custom.i18n.resources"  value="message"></constant>

    <!-- 结果集 -->

    <include file="config/result_struts.xml"></include>

</struts>

result_struts.xml

<?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>

    <package name="result" extends="struts-default">

        <action name="ResultAction" class="result.ResultAction" method="execute">

            <result name="success" type="dispatcher">

                /WEB-INF/result_success.jsp

            </result>

            <result name="input" type="dispatcher">

                result.jsp

            </result>

        </action>

    </package>

</struts>

message_zh_CN.properties

login.username=\u7528\u6237\u540D

login.submit=\u767B\u5F55

login.hello=\u4F60\u597D{0},\u6211\u662F{1}

login.tom=\u6C64\u59C6

login.amos=\u963F\u83AB\u65AF

result.username.required=\u7528\u6237\u540D\u5FC5\u586B

result.username.mustchinese=\u5FC5\u987B\u4E3A\u4E2D\u6587

message_en_US.properties

login.username=USERNAME

login.submit=LOGIN

login.hello=hello {0},I am {1}

login.tom=TOM

login.amos=AMOS

result.username.required=username cannot be empty

result.username.mustchinese=username must be chinese

首先，项目运行时,通过struts.xml将配置文件加载到内存中，其中strutx.xml加载了result_struts.xml,message_zh_CN.properties,message_en_US.properties三个配置文件。

两个properties文件分别对应的是中英文提示信息，这里在项目启动时已经加载到内存中去了。

其次，result.jsp页面是程序入口==>调用了ResultAction==>ResultAction是在result_struts.xml中配置的ResultAction.java中的execute方法==>

调用validate()验证方法==>validate()验证方法主要作用是对username进行验证，必须是非空和中文，否则会使用getText()方法调用properties中配置的提示信息,将错误提示信息添加到addFieldError()方法中。

最后，通过struts的标签<s:textfield>将错误提示信息显示输出到浏览器中。

总结，对中文的验证主要是采用正则表达式,即使用unicode编码汉字的范围;对错误信息的分离抽取主要使用properties文件进行配置,然后再通过struts标签进行错误信息的输出,这里同时也用到了上篇文章的国际化的知识.

四、结果(result)类型

一般情况下,当Action中的execute方法的返回值为null时不需要配置<action>下的<result>标签,但如果有返回值时则需要将result标签进行配置.

在struts2-core.jar包里有struts-default.xml默认配置文件,其中有这样一段:

<result-types>

            <result-type name="chain" class="com.opensymphony.xwork2.ActionChainResult"/>

            <result-type name="dispatcher" class="org.apache.struts2.dispatcher.ServletDispatcherResult" default="true"/>

            <result-type name="freemarker" class="org.apache.struts2.views.freemarker.FreemarkerResult"/>

            <result-type name="httpheader" class="org.apache.struts2.dispatcher.HttpHeaderResult"/>

            <result-type name="redirect" class="org.apache.struts2.dispatcher.ServletRedirectResult"/>

            <result-type name="redirectAction" class="org.apache.struts2.dispatcher.ServletActionRedirectResult"/>

            <result-type name="stream" class="org.apache.struts2.dispatcher.StreamResult"/>

            <result-type name="velocity" class="org.apache.struts2.dispatcher.VelocityResult"/>

            <result-type name="xslt" class="org.apache.struts2.views.xslt.XSLTResult"/>

            <result-type name="plainText" class="org.apache.struts2.dispatcher.PlainTextResult" />

            <result-type name="postback" class="org.apache.struts2.dispatcher.PostbackResult" />

        </result-types>

关于result-types,即结果类型,其中经常用到的有dispatcher,redirect,然后class有其对应的类来实现所配置的功能.这里来简单介绍下redirectAction:

<result-type name="redirectAction" class="org.apache.struts2.dispatcher.ServletActionRedirectResult"/>

选中类路径,eclipse中ctrl+shift+t能跳转到对应的实现类,查看一下源码,其中可选属性有actionName,namespace,method,下面以实例来说明其使用方法.

redirectAction从名字上理解为重定向action,重定向时浏览器中的路径是会发生变化的.这里要实现的需求为:从一个FromAction重定向到另一个ToAction

1.具体代码为:

FromAction.java

package result;

import com.opensymphony.xwork2.ActionSupport;

public class FromAction extends ActionSupport{

    private static final long serialVersionUID = -3310226638999302819L;

    public String execute() throws Exception {

        return "gotoAction";

    }

}

ToAction.java

package result;

import com.opensymphony.xwork2.ActionSupport;

public class ToAction extends ActionSupport{

    private static final long serialVersionUID = 6648927017489122451L;

    public String execute() throws Exception {

        return null;

    }

}

result_struts.xml

<?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>

    <package name="result" extends="struts-default">

        <action name="ResultAction" class="result.ResultAction" method="execute">

            <result name="success" type="dispatcher">

                /WEB-INF/result_success.jsp

            </result>

            <result name="input" type="dispatcher">

                result.jsp

            </result>

        </action>

        <action name="FromAction" class="result.FromAction" method="execute">

            <result name="gotoAction" type="redirectAction">

                <param name="actionName">ToAction</param>

                <!-- <param name="namespace">/</param> <param name="method">execute</param> -->

            </result>

        </action>

        <action name="ToAction" class="result.ToAction" method="execute"></action>

    </package>

</struts>

2.代码分析

其中result中的主要实现代码为:

<result name="gotoAction" type="redirectAction">

<param name="actionName">ToAction</param>

</result>

gotoAction为FromAction中execute方法的return value值.
redirectAction为result的类型值
actionName为参数名称,这里与源码中定义的参数名称一致
ToAction为将要重定向到另外一个Action的名称.
还可以配置namespace,method等,这里就不再介绍.

3.效果

1)输入FromAction,回车

2)url跳转到ToAction

4.result配置提高

1).如果一个package中多个action标签出现同样的return value="success",如果每个都配置一遍就太过麻烦,这里以上面例子为基础将ToAction的return null 改为 return SUCCESS后,配置文件也跟着改,配置一个返回值为success的全局result:

        <global-results>

            <result name="success" type="dispatcher">

            /WEB-INF/success.jsp

            </result>

        </global-results>

将全局result转发到success.jsp中.

2).相对应的还有局部的result:

       <action name="ToAction" class="result.ToAction" method="execute">

             <result name="success" type="dispatcher">

            /WEB-INF/part_success.jsp

            </result>

        </action>

3)如果局部和全局result共存时以哪个为准???

这里经过测验得出以局部的为准.

全部的result_struts.xml

<?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>

    <package name="result" extends="struts-default">

        <global-results>

            <result name="success" type="dispatcher">

            /WEB-INF/success.jsp

            </result>

        </global-results>

        <action name="ResultAction" class="result.ResultAction" method="execute">

            <!-- <result name="success" type="dispatcher">

                /WEB-INF/result_success.jsp

            </result> -->

            <result name="input" type="dispatcher">

                result.jsp

            </result>

        </action>

        <action name="FromAction" class="result.FromAction" method="execute">

            <result name="gotoAction" type="redirectAction">

                <param name="actionName">ToAction</param>

                <!-- <param name="namespace">/</param> <param name="method">execute</param> -->

            </result>

        </action>

        <action name="ToAction" class="result.ToAction" method="execute">

            <!-- <result name="success" type="dispatcher">

            /WEB-INF/part_success.jsp

            </result> -->

        </action>

    </package>

</struts>

本文源码:https://github.com/amosli/strut2_learn 结果(result)类型