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;
}
}<a href=”user/user!add?name=a&password=8″>添加用户</a>
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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