1,使用域模型时，只有传参user.age=8,才会new一个user对象，当然也可以再action中手动new一个user对象。所以初始化域模型时，可以自己构造，也可以传值，但这时必须有空的构造方法。
2.当用chain跳转到另一个action时，值栈中会有两个action对象
3.object graph navigation language(ognl) 对象图导航语言
strust.xml
<struts> <constant name="struts.enable.DynamicMethodInvocation" value="false" /> <constant name="struts.devMode" value="true" /> <constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant>//允许调用静态方法 <include file="/com/bjsxt/struts2/ognl/ognl.xml"/> <!-- <include file="/testognl/testognl.xml"/>--> </struts>
ognl.xml
<struts> <package name="ognl" extends="struts-default"> <action name="ognl" class="com.bjsxt.struts2.ognl.OgnlAction"> <result>/ognl.jsp</result> </action> <action name="test" class="com.bjsxt.struts2.ognl.TestAction"> <result type="chain">ognl</result>//调用这个时值栈中会有两个action对象 </action> </package> </struts>
OgnlAction .java
public class OgnlAction extends ActionSupport { private Cat cat; private Map<String, Dog> dogMap = new HashMap<String, Dog>(); private Set<Dog> dogs = new HashSet<Dog>(); private String password; private User user; private String username; private List<User> users = new ArrayList<User>(); 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 Cat getCat() { return cat; } public Map<String, Dog> getDogMap() { return dogMap; } public Set<Dog> getDogs() { return dogs; } public String getPassword() { return password; } public User getUser() { return user; } public String getUsername() { return username; } public List<User> getUsers() { return users; } 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; } }
ognl.jsp
<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.bjsxt.struts2.ognl.S@s()"/></li> //@类名@静态方法 此时需要在struts.xml中配置 <constant name="struts.ognl.allowStaticMethodAccess" value="true"></constant> <li>访问静态属性：<s:property value="@com.bjsxt.struts2.ognl.S@STR"/></li> //@类名@静态属性 <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.bjsxt.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>//set集合是无序的，所以这样取值不可以 <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>//^指的是开头 <li>投影：<s:property value="users.{$#this.age>1}.{age}"/></li>//$指的是结尾 <li>投影：<s:property value="users.{$#this.age>1}.{age} == null"/></li>//返回FALSE <hr /> <li>[]:<s:property value="[0].username"/></li>//[0]指的是从0开始的所有对象 </ol> <s:debug></s:debug> </body>