第一部分:代码
//前端 <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> 访问属性<br/> <a href="<%=contextPath %>/ognl.action?username=u&password=p">ognl</a> </body> </html>
//web.xml <struts> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="true" /> <constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant> <include file="/com/struts2/ognl/ognl.xml"/> </struts>
//ognl.xml <struts> <package name="ognl" extends="struts-default"> <action name="ognl" class="com.struts2.ognl.OgnlAction"> <result>/ognl.jsp</result> </action> <action name="test" class="com.struts2.ognl.TestAction"> <result type="chain">ognl</result> </action> </package> </struts>
//类包 //ognl.java package com.struts2.ognl; import java.util.ArrayList; import java.util.HashMap; import java.util.HashSet; import java.util.List; import java.util.Map; import java.util.Set; import com.opensymphony.xwork2.ActionSupport; public class OgnlAction extends ActionSupport { private String password; private String username; private User user; private Cat cat; private List<User> users = new ArrayList<User>(); private Set<Dog> dogs = new HashSet<Dog>(); private Map<String, Dog> dogMap = new HashMap<String, Dog>(); public OgnlAction() { users.add(new User(1)); users.add(new User(2)); users.add(new User(3)); dogs.add(new Dog("dog1")); dogs.add(new Dog("dog2")); dogs.add(new Dog("dog3")); dogMap.put("dog100", new Dog("dog100")); dogMap.put("dog101", new Dog("dog101")); dogMap.put("dog102", new Dog("dog102")); } public String execute() { return SUCCESS; } public String getPassword() { return password; } public String getUsername() { return username; } public User getUser() { return user; } public Cat getCat() { return cat; } public List<User> getUsers() { return users; } public Map<String, Dog> getDogMap() { return dogMap; } public Set<Dog> getDogs() { return dogs; } public String m() { return "hello"; } public void setCat(Cat cat) { this.cat = cat; } public void setDogMap(Map<String, Dog> dogMap) { this.dogMap = dogMap; } public void setDogs(Set<Dog> dogs) { this.dogs = dogs; } public void setPassword(String password) { this.password = password; } public void setUser(User user) { this.user = user; } public void setUsername(String username) { this.username = username; } public void setUsers(List<User> users) { this.users = users; } } //user.java package com.struts2.ognl; public class User { private int age = 8; public User() { } public User(int age) { super(); this.age = age; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } @Override public String toString() { return "user" + age; } }
//cat.java package com.struts2.ognl; public class Cat { private Dog friend; public Dog getFriend() { return friend; } public void setFriend(Dog friend) { this.friend = friend; } public String miaomiao() { return "miaomiao"; } } //dog.java package com.struts2.ognl; public class Cat { private Dog friend; public Dog getFriend() { return friend; } public void setFriend(Dog friend) { this.friend = friend; } public String miaomiao() { return "miaomiao"; } }
//展示 </head> <body> <ol> <li>访问值栈中的action的普通属性: username = <s:property value="username"/> </li> <li>访问值栈中对象的普通属性(get set方法):<s:property value="user.age"/> | <s:property value="user['age']"/> | <s:property value="user[\"age\"]"/> | wrong: <%--<s:property value="user[age]"/>--%></li> <li>访问值栈中对象的普通属性(get set方法): <s:property value="cat.friend.name"/></li> <li>访问值栈中对象的普通方法:<s:property value="password.length()"/></li> <li>访问值栈中对象的普通方法:<s:property value="cat.miaomiao()" /></li> <li>访问值栈中action的普通方法:<s:property value="m()" /></li> <hr /> <li>访问静态方法:<s:property value="@com.struts2.ognl.S@s()"/></li> <li>访问静态属性:<s:property value="@com.struts2.ognl.S@STR"/></li> <li>访问Math类的静态方法:<s:property value="@@max(2,3)" /></li> <hr /> <li>访问普通类的构造方法:<s:property value="new com.struts2.ognl.User(8)"/></li> <hr /> <li>访问List:<s:property value="users"/></li> <li>访问List中某个元素:<s:property value="users[1]"/></li> <li>访问List中元素某个属性的集合:<s:property value="users.{age}"/></li> <li>访问List中元素某个属性的集合中的特定值:<s:property value="users.{age}[0]"/> | <s:property value="users[0].age"/></li> <li>访问Set:<s:property value="dogs"/></li> <li>访问Set中某个元素:<s:property value="dogs[1]"/></li> <li>访问Map:<s:property value="dogMap"/></li> <li>访问Map中某个元素:<s:property value="dogMap.dog101"/> | <s:property value="dogMap['dog101']"/> | <s:property value="dogMap[\"dog101\"]"/></li> <li>访问Map中所有的key:<s:property value="dogMap.keys"/></li> <li>访问Map中所有的value:<s:property value="dogMap.values"/></li> <li>访问容器的大小:<s:property value="dogMap.size()"/> | <s:property value="users.size"/> </li> <hr /> <li>投影(过滤):<s:property value="users.{?#this.age==1}[0]"/></li> <li>投影:<s:property value="users.{^#this.age>1}.{age}"/></li> <li>投影:<s:property value="users.{$#this.age>1}.{age}"/></li> <li>投影:<s:property value="users.{$#this.age>1}.{age} == null"/></li> <hr /> <li>[]:<s:property value="[0].username"/></li> </ol> <s:debug></s:debug> </body> </html>
第二部分:分析
<a href="<%=contextPath %>/ognl.action?username=u&password=p">ognl</a>-> 点击之后,根据配置文件里里面的配置,找到文件包含<include file="/com/struts2/ognl/ognl.xml"/>
-> 查找olnl.xml文件
->
<struts> <package name="ognl" extends="struts-default"> <action name="ognl" class="com.struts2.ognl.OgnlAction"> <result>/ognl.jsp</result> </action> <action name="test" class="com.struts2.ognl.TestAction"> <result type="chain">ognl</result> </action> </package> </struts>-> 根据xml配置文件里面的action关联的类,构造类对象;
-> 根据ognl.java构造ognl对象;
-> 展示阶段进行取值显示,有几种访问方式需要注意:
-> 访问值栈中属性,值栈中对象的方法,静态方法,静态属性,容器对象;
访问值栈中的action的普通属性
值栈中对象的普通属性
值栈中对象的普通方法
值栈中action的普通方法
静态方法访问方式@类名@方法名
需要在web.xml中设置<constant name="struts.ognl.allowStaticMethodAccess"value="true"></constant>
查看默认设置的方法:/Struts2_1900_OGNL / WebRoot / WEB-INF / lib / struts2-core-2.1.6.jar /default.properties
访问集合
-> 调用方法
http://localhost:8080/Struts2_1900_OGNL/ognl.action?username=u&password=p&user.age = 19&cat.friend.name =oudy
第三部分;讨论
Object Graph Navigation Language对象图导航语言
第四部分:有关投影的讨论
投影即过滤功能。过滤写法:
<li>投影(过滤):<s:property value="users.{?#this.age==1}[0]"/></li> <li>投影:<s:property value="users.{^#this.age>1}.{age}"/></li> <li>投影:<s:property value="users.{$#this.age>1}.{age}"/></li> <li>投影:<s:property value="users.{$#this.age>1}.{age} == null"/></li>以? ^ $ 开头加上过滤条件,和正则表达式不相同;
this表示循环过程中的对象,帮助你做一些循环;
<li>投影(过滤):<s:property value="users.{?#this.age==1}"/></li>表示从从users中取出age=1的那一个,结果是一个集合;
<li>投影(过滤):<s:property value="users.{?#this.age==1}[0]"/></li>表示从从users中取出age=1的第一个,结果是一个;<li>投影:<s:property value="users.{$#this.age>1}.{age}"/></li>表示从从users中取出age>1的集合结尾的那一个;