OGNL表达式访问值栈:
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:
public class Cat {
//cat有一个朋友是dog
private Dog friend;
public Dog getFriend() {
return friend;
}
public void setFriend(Dog friend) {
this.friend = friend;
}
public String miaomiao() {
return "miaomiao";
}
}
Dog:
public class Dog {
private String name;
public Dog() {
}
public Dog(String name) {
super();
this.name = name;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "dog: " + name;
}
}
Action:
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;
}
}
struts.xml配置文件:
<struts>
<package name="ognl" extends="struts-default">
<action name="ognl" class="com.mengxiangyue.struts2.ognl.OgnlAction">
<result>/ognl.jsp</result>
</action>
</package>
</struts>
通过OGNL在jsp页面去访问这些属性:
<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>
OGNL访问静态方法,集合类:
S类:
public class S {
public static String STR = "STATIC STRING";
public static String s() {
return "static method";
}
}
<!--在我们访问静态方法的时候,需要使用@符号,跟上完整的类名,然后在跟@符号,加上具体的静态方法或者属性
在OGNL中使用@@符号可以直接使用Math类的方法,使用方法是@@+对应的Math方法 -->
<li>访问静态方法:<s:property value="@com.mengxiangyue.struts2.ognl.S@s()"/></li>
<li>访问静态属性:<s:property value="@com.mengxiangyue.struts2.ognl.S@STR"/></li>
<li>访问Math类的静态方法:<s:property value="@@max(2,3)" /></li>
<li>访问普通类的构造方法:<s:property value="new com.mengxiangyue.struts2.ognl.User(8)"/></li>
<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>
<!-- 访问Map中key或者value的时候都是使用的复数 --> <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>
OGNL投影:
<!-- ?表示选择某一个,这个表示选择user.age=1的所有的user中的第一个 -->
<li>投影(过滤):<s:property value="users.{?#this.age==1}[0]"/></li>
<!-- ^ 表示第一个,这个表示选择user.age>1的第一个user的age属性 -->
<li>投影:<s:property value="users.{^#this.age>1}.{age}"/></li>
<!-- $ 表示最后一个,这个表示选择user.age>1的最后一个user的age属性 -->
<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>