Struts2中使用OGNL表达式投影(过滤)的实战应用.doc

Struts2中使用OGNL表达式投影（过滤）的实战应用1.集合的投影（过滤）有以下三种方式： a.“?#”：投影（过滤）所有符合条件的集合，如：users.?#this.age ； b.“#”：投影（过滤）第一个符合条件的元素，如：users.#this.age ； c.“$#”：投影（过滤）最后一个符合条件的元素，如：users.$#this.age 。2.“this”表示集合中的元素；3.投影（过滤）操作返回的是一个集合，可以使用索引取得集合中指定的元素，如：users.?#this.age 0。实例：web.xml: hello.jsp struts2 org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter struts2 /* struts.xml:view sourceprint?01 !- HelloWorld /example - /addSuccess.jsp UserAction.java:view sourceprint?01 package .ahau.mgc.struts2.action; 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 .ahau.mgc.struts2.model.User; import com.opensymphony.xwork2.ActionSupport; public class UserAction extends ActionSupport private String userName; private User user; private List users = new ArrayList(); private Set usersSet = new HashSet(); private Map usersMap = new HashMap(); public UserAction() users.add(new User(1, ); users.add(new User(2, ); users.add(new User(3, ); usersSet.add(new User(1, ); usersSet.add(new User(2, ); usersSet.add(new User(3, ); usersMap.put(u1, new User(1, ); usersMap.put(u2, new User(2, ); usersMap.put(u3, new User(3, ); public String execute() return SUCCESS; public String getUserName() return this.userName; public void setUserName(String userName) this.userName = userName; public User getUser() return user; public void setUser(User user) this.user = user; public String test() return Action Method; public List getUsers() return users; public void setUsers(List users) this.users = users; public Set getUsersSet() return usersSet; public void setUsersSet(Set usersSet) this.usersSet = usersSet; public Map getUsersMap() return usersMap; public void setUsersMap(Map usersMap) this.usersMap = usersMap; User.java:view sourceprint?01 package .ahau.mgc.struts2.model; public class User private String userName; private int age; private User firend; public User() public User(String userName, int age) super(); this.userName = userName; this.age = age; public User getFirend() return firend; public void setFirend(User firend) this.firend = firend; public String getUserName() return this.userName; public void setUserName(String userName) this.userName = userName; Override public String toString() return User( + this.userName + , + this.age + ); public String hello() return Hello World!; public int getAge() return age; public void setAge(int age) this.age = age; index.jsp:view sourceprint?01 base href= ResultParam !- - user addSuccess.jsp:view sourceprint?01 base href= Dynamic !- - User Add Success! 投影（过滤）所有符合条件的集合：users