Struts2—->action

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发布于 2022-07-05 09:14:26

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发布于 2022-07-05 09:14:26

文章被收录于专栏：全栈程序员必看全栈程序员必看

Action

具体视图的返回可以由用户自己定义的Action来决定，具体的手段是根据返回的字符串找到对应的配置项，来决定视图的内容

一、具体Action的实现 1、可以是一个普通的java类，里面有public String execute方法即可

package com.ncepu.struts;

public class Action1 {
	public String execute()
	{
		System.out.print("在普通类中定义execute()方法");
		return("success");
	}


}

2、或者实现Action接口

package com.ncepu.struts;

import com.opensymphony.xwork2.Action;

public class Action2 implements Action {


	public String execute() throws Exception {
	System.out.print("实现Action接口");
		return "success";
	}
}

3、不过最常用的是从ActionSupport继承，好处在于可以直接使用Struts2封装好的方法

package com.ncepu.struts;

import com.opensymphony.xwork2.ActionSupport;

public class Action3 extends ActionSupport {
	public String execute()
	{
		System.out.print("继承ActionSupport类");
		return("success");
	}


}

二、helloworld 例子中里面action没有配置class

<action name="hello">
	    <result>
				/index.jsp
            </result>
		</action>

就是默认为ActionSupport，里面的execute方法返回success

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

三、DMI（dynami method invocation）动态方法调用

1、action不一定非得执行execute方法，可以指定调用具体的方法。不写的话默认为execute方法

action方法中的method方法指定调用具体的方法。

<action name="action1" class="com.ncepu.struts2.Action1" method="notexecute">
   <result name="success">
    /index.jsp
   </result>
  </action>

2、DMI 动态方法调用用!号

<action name="user" class="com.ncepu.struts2.Action1" >
   <result name="success">
    /add.jsp
     </result>
  </action>

jsp中<a href=”user!add”>添加学生</a> 自动调用Action1下面的add方法也可直接访问 http://localhost:8080/Struts2_DMI/user!add

四、通配符 action配置

<action name="*_*" class="com.ncepu.struts2.{1}Action" method="{2}{1}">
   <result name="success">
    /{2}_{1}.jsp
            </result>
  </action>

jsp页面链接

  <a href="Student_add">添加学生</a>
  <a href="Student_delete">删除学生</a>
  <a href="Teacher_add">添加教师</a>
  <a href="Teacher_delete">删除教师</a>

也可直接访问http://localhost:8080/Struts2_tongpeifu2/Student_delete思考: 仅用动态方法调用，result对于不同的action无法配置。要不只能到学生的jsp 要不只能到教师的jsp。 五、action接收参数 1、<a href=”user!add?name=12345&password=12345″>添加学生</a> 其中name和password是 action中的参数，并且有相应的getter和setter方法 2、使用Domain Model接收参数（最常用）

<a href=”user/user!add?user.name=a&user.password=8″>添加用户</a> 其中user是action中的参数，有getter和setter方法，而user是我们自己定义的域模型，里面有name和password参数

package com.ncepu.struts2;

import com.ncepu.struts2.entity.User;

public class Action1 {

private User user;

	public User getUser() {
	return user;
}

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

	public String add() {
        System.out.println("添加的name="+this.user.getName()+"添加的password="+this.user.getPassword());
		return ("success");
	}

}

或者用DTO传输数据，相当于VO value object ）,比如注册的时候，得输入两遍密码，可以定义一个vo，包含3个属性，用户名，密码，确认密码，然后根据vo生成实体，该实体只包含用户名和密码两个属性。

3、使用ModelDriven接收参数

action实现ModelDriven接口，里面生成一个模型对象

public class Action1 extends ActionSupport implements ModelDriven<User>{
 private User user = new User();
 public String add() {
  System.out.println("name=" + user.getName());
  System.out.println("age=" + user.getPassword());
  return SUCCESS;
 }
 public User getModel() {
  return user;
 }
 
}

会直接把属性设置到getModel方法获得的模型上面。

六、中文乱码问题

<form action=”user!add” method=”post”> 必须为post ，get就出错，action得不到值

七、简单验证

 public String add() {
  if(name == null || !name.equals("admin")) {
   this.addFieldError("nameerror", "name is error");
   this.addFieldError("nameerror", "name is too long");
   this.addFieldError("passworderror", "password is not correct!");
   return ERROR;
  } 
  return SUCCESS;
 
 }

相应的在页面上

  <s:fielderror fieldName="nameerror" theme="simple" />
  <s:fielderror fieldName="passworderror" theme="simple" />
  <s:property value="errors.nameerror" />  <s:property value="errors.nameerror[0]" />
  <s:property value="errors.nameerror[1]" />
  <s:property value="errors.passworderror" /><s:property value="errors.passworderror[0]" />
  <s:debug></s:debug>

errors fieldErrors和action中所有的属性都会存在Value Stack Contents中 fielderror相当于一个数组，可以取所有，也可以取一个。八、获得web元素4种方法

map类型的request session application（1、通过容器获得，2、实现aware接口通过IoC获得）

真实类型的request session application（3、通过容器获得，4、实现aware接口通过IoC获得）

1、通过容器获得map类型的request session application

package com.struts2.action;

import java.util.Map;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;

public class Action1 extends ActionSupport {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private Map<String, Object> request;
	private Map<String, Object> session;
	private Map<String, Object> application;

	public Action1() {
		request = (Map) ActionContext.getContext().get("request");
		session = ActionContext.getContext().getSession();
		application = ActionContext.getContext().getApplication();
	}

	public String execute() {
		request.put("r1", "requestpara");
		session.put("s1", "sessionpara");
		application.put("a1", "applicationpara");
		return SUCCESS;

	}

}

2、实现aware接口通过IoC获得map类型的request session application,（最常用）

package com.struts2.action;

import java.util.Map;

import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;

import com.opensymphony.xwork2.ActionSupport;

public class Action2 extends ActionSupport implements RequestAware,
		SessionAware, ApplicationAware {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private Map<String, Object> request;
	private Map<String, Object> session;
	private Map<String, Object> application;

	public void setRequest(Map<String, Object> request) {
		this.request = request;

	}

	public void setSession(Map<String, Object> session) {
		this.session = session;
	}

	public void setApplication(Map<String, Object> application) {
		this.application = application;

	}

	public String execute() {
		request.put("r1", "requestpara");
		session.put("s1", "sessionpara");
		application.put("a1", "applicationpara");
		return SUCCESS;

	}
}

3、通过容器获得真实类型的request session application

package com.struts2.action;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.struts2.ServletActionContext;

import com.opensymphony.xwork2.ActionSupport;

public class Action3 extends ActionSupport {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	HttpServletRequest request;
	HttpSession session;
	ServletContext application;

	public Action3() {
		request = ServletActionContext.getRequest();
		session = request.getSession();
		application = session.getServletContext();
	}

	public String execute() {
		request.setAttribute("r1", "requestpara");
		session.setAttribute("s1", "sessionpara");
		application.setAttribute("a1", "applicationpara");
		return SUCCESS;

	}

}

4、实现aware接口通过IoC获得真实类型的request session application

package com.struts2.action;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

import org.apache.struts2.interceptor.ServletRequestAware;

import com.opensymphony.xwork2.ActionSupport;

public class Action4 extends ActionSupport implements ServletRequestAware {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	HttpServletRequest request;
	HttpSession session;
	ServletContext application;

	public void setServletRequest(HttpServletRequest request) {
		this.request = request;
		this.session = request.getSession();
		application = session.getServletContext();

	}

	public String execute() {
		request.setAttribute("r1", "requestpara");
		session.setAttribute("s1", "sessionpara");
		application.setAttribute("a1", "applicationpara");
		return SUCCESS;

	}
}

login_success.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
    <%@taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030" />
<title>Insert title here</title>
</head>
<body>
	User Login Success!
	<br />
	<s:property value="#request.r1"/> | <%=request.getAttribute("r1") %> <br />
	<s:property value="#session.s1"/> | <%=session.getAttribute("s1") %> <br />
	<s:property value="#application.a1"/> | <%=application.getAttribute("a1") %> <br />
	<s:property value="#attr.a1"/><br />
	<s:property value="#attr.s1"/><br />
	<s:property value="#attr.r1"/><br />
	<s:debug></s:debug>
	<br />
</body>
</html>

九、include 包含其他配置action的xml文件

<struts>
 <constant name="struts.devMode" value="true" />
 <include file="module1.xml"></include>
</struts>

而module1.xml文件中配置着action

十、namespace的默认action

<struts>
 <constant name="struts.devMode" value="true" />
	<package name="default" namespace="/action" extends="struts-default">
	<default-action-ref name="action1"></default-action-ref>
	<action name="action1" class="com.ncepu.struts2.Action1">
			<result name="success">
				/default.jsp
            </result>
	</action>	
	</package>
</struts>

每个package可以有一个默认的action，当没有匹配的时候时，就使用它，如用户输入错误时，根据他跳到默认的错误界面

十一、路径问题

1、action跳转

result都需要指定目标资源的URL，如果这个路径以“/”开始。代表的是应用程序根目录。

<package name="default" namespace="/path" extends="struts-default">
	
		<action name="hello">
			<result>
				/path.jsp
                        </result>
		</action>
	</package>

其中path在webroot根目录下。能找到。如果是下面的配置

<package name="default" namespace="/path" extends="struts-default">
	
		<action name="hello">
			<result>
				path.jsp
                        </result>
		</action>
	</package>

则不行，当前目录是Struts2_path/path/hello.action，相当于在当前目录查找，即/Struts2_path/path/path.jsp

2、jsp链接都使用绝对路径：

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->
  </head>
  
  <body>
  <a href="path.jsp"> path.jsp</a> <br>
  </body>
</html>

定义path ，然后再head便签中添加<base href=”<%=basePath%>”>，相当于都从web应用的根目录下面找。

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原始发表：2021年8月1，如有侵权请联系 cloudcommunity@tencent.com 删除

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