Struts2整合REST Plugin

1.添加依赖的Jar

 

 <dependency>
  	<groupId>org.apache.struts</groupId>
  	<artifactId>struts2-convention-plugin</artifactId>
  	<version>2.1.6</version>
 </dependency>
 <dependency>
  	<groupId>org.apache.struts</groupId>
  	<artifactId>struts2-rest-plugin</artifactId>
  	<version>2.1.6</version>
 </dependency>

2.参数配置

// Action的类名以Controller为后缀

<constant name="struts.convention.action.suffix" value="Controller"/>

// Action中没有@Action注解也创建映射

<constant name="struts.convention.action.mapAllMatches" value="true"/>

<constant name="struts.convention.default.parent.package" value="rest-default"/>

// Action类所在的包

<constant name="struts.convention.action.packages" value="com.st.web"/>

// 搜索以web为结尾的包

<constant name="struts.convention.package.locators" value="web"/>

3.BaseController设计

package com.st.web;

import java.io.Serializable;

import org.apache.struts2.rest.HttpHeaders;

import com.opensymphony.xwork2.ModelDriven;
import com.opensymphony.xwork2.Preparable;

public abstract class BaseController<T> implements ModelDriven<T>,
		Serializable, Preparable {
	private static final long serialVersionUID = 7449478681110941532L;
	protected T entity;

	/**
	 * GET: /{model}
	 */
	public abstract HttpHeaders index();

	/**
	 * POST: /{model}
	 */
	public abstract HttpHeaders create();

	/**
	 * PUT: /{model}/{id}
	 */
	public abstract String update();

	/**
	 * DELETE: /{model}/{id}
	 */
	public abstract String destroy();

	/**
	 * GET: /{model}/{id}
	 */
	public abstract HttpHeaders show();

	/**
	 * GET: /{model}/{id}/edit
	 */
	public abstract String edit();

	/**
	 * GET: /{model}/new
	 */
	public abstract String editNew();

	@Override
	public T getModel() {
		return entity;
	}

	/**
	 * 子类通过重写此方法初始化实体类
	 */
	@Override
	public abstract void prepare();
}

什么时候需要返回HttpHeaders？

当返回的给用户的响应需要 在http头部自定义一些内容 ，需要返回HttpHeaders的实现类。

官方文档原文：

The REST Plugin adds support for action methods that return HttpHeaders objects as a way for the action to have more control over the response. 

REST Plugin HttpHeaders的实现类DefaultHttpHeaders有哪些更多的控制？

String resultCode;

int status = SC_OK;

Object etag; //被请求变量的实体值

Object locationId;

String location; // 响应报头域用于重定向接受者到一个新的位置

boolean disableCaching; // 用于指定缓存指令，缓存指令是单向的（响应中出现的缓存指令在请求中未必会出现），且是独立的（一个消息的缓存指令不会影响另一个消息处理的缓存机制）

boolean noETag = false;

Date lastModified; //标记此文件在服务期端最后被修改的时间

Last-Modified和Etags如何帮助提高性能?
        聪明的开发者会把Last-Modified 和ETags请求的http报头一起使用，这样可利用客户端（例如浏览器）的缓存。因为服务器首先产生 Last-Modified/Etag标记，服务器可在稍后使用它来判断页面是否已经被修改。本质上，客户端通过将该记号传回服务器要求服务器验证其（客户端）缓存。 
        过程如下:
        1. 客户端请求一个页面（A）。 
        2. 服务器返回页面A，并在给A加上一个Last-Modified/ETag。 
        3. 客户端展现该页面，并将页面连同Last-Modified/ETag一起缓存。 
        4. 客户再次请求页面A，并将上次请求时服务器返回的Last-Modified/ETag一起传递给服务器。 
        5. 服务器检查该Last-Modified或ETag，并判断出该页面自上次客户端请求之后还未被修改，直接返回响应304和一个空的响应体。

4.自定义的Controller

package com.st.web;

import java.util.Date;
import java.util.List;

import org.apache.struts2.convention.annotation.Result;
import org.apache.struts2.convention.annotation.Results;
import org.apache.struts2.rest.DefaultHttpHeaders;
import org.apache.struts2.rest.HttpHeaders;

import com.st.entity.User;
import com.st.service.UserService;

@Results( { @Result(name = "success", type = "redirectAction", params = {
		"actionName", "user" }) })
public class UserController extends BaseController<User> {
	private static final long serialVersionUID = -2697052455833496406L;
	private UserService userService;
	private List<User> list;
	private Long id;

	public HttpHeaders create() {
		entity.setCreateTime(new Date());
		userService.save(entity);
		return new DefaultHttpHeaders("success");
	}

	public String destroy() {
		userService.delete(entity.getId());
		return "success";
	}

	public String edit() {
		return "edit";
	}

	public String editNew() {
		entity = new User();
		return "editNew";
	}

	public HttpHeaders index() {
		list = userService.list();
		return new DefaultHttpHeaders("index").disableCaching();
	}

	public HttpHeaders show() {
		return new DefaultHttpHeaders("show");
	}

	public String update() {
		userService.save(entity);
		return "success";
	}

	public void setUserService(UserService userService) {
		this.userService = userService;
	}

	public UserService getUserService() {
		return userService;
	}

	@Override
	public User getModel() {
		return entity;
	}

	public void setId(Long id) {
		if (null != id) {
			System.out.println("id:" + id);
			entity = userService.get(id);
		} else {
			this.id = id;
		}
	}

	public Long getId() {
		return id;
	}

	public List<User> getList() {
		return list;
	}

	public void setList(List<User> list) {
		this.list = list;
	}

	@Override
	public void prepare() {
		entity = new User();
	}
}

 

5.View层

在WEB-INF\content目录下建立以下文件：user-edit.jsp,user-editNew.jsp,user-index.jsp。

user-index.jsp--以列表显示所有的User

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>User</title>
  </head>
  	
  <body>
  	<a href="">List</a>
  	<a href="user/new">Add User</a>
  	
  	<table border="0">
  		<tr>
  			<td width="100">Login Name</td>
  			<td width="120">Password</td>
  			<td width="100">Create Time</td>
  			<td width="80">Manage</td>
  		</tr>
  		<s:iterator value="list" id="u">
	  		<tr>
	  			<td><s:property value="#u.loginName"/></td>
	  			<td><s:property value="#u.password"/></td>
	  			<td><s:date format="yyyy-MM-dd HH:mm" name="#u.createTime"/></td>
	  			<td>
	  				<a href="user/${u.id }/edit">Edit</a>
	  				<span>|</span>
	  				<a href="user/${u.id}?_method=DELETE">Delete</a>
	  			</td>
	  		</tr>
  		</s:iterator>
  	</table>
  </body>
</html>

 

user-editNew.jsp--创建新用户

<%@ page contentType="text/html; charset=UTF-8" language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>User</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
  </head>
  
  <body>	
  	<s:form action="%{#request.contextPath}/user" theme="simple" method="post">
  	<table>
  		<tr>
  			<td>Login Name:<s:textfield name="loginName"/></td>
  		</tr>
  		<tr>
  			<td>Password:<s:password name="password"/></td>
  		</tr>
  		<tr>
  			<td><s:submit value="Submit"/><s:reset value="Cancel" onclick="history.back()"/></td>
  		</tr>
  	</table>
  	</s:form>
  </body>
</html>

 

user-edit.jsp--编辑用户信息

<%@ page contentType="text/html; charset=UTF-8" language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <title>User</title>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
  </head>
  
  <body>	
  	<s:form action="%{#request.contextPath}/user/%{id}" theme="simple" method="post">
  	<s:hidden name="_method" value="put" />
  	<table>
  		<tr>
  			<td>ID:<s:textfield name="id" disabled="true"/></td>
  		</tr>
  		<tr>
  			<td>Login Name:<s:textfield name="loginName"/></td>
  		</tr>
  		<tr>
  			<td>Password:<s:password name="password"/></td>
  		</tr>
  		<tr>
  			<td><s:submit value="Submit"/><s:reset value="Cancel" onclick="history.back()"/></td>
  		</tr>
  	</table>
  	</s:form>
  </body>
</html>