Struts2整合REST Plugin

1.添加依赖的Jar

Xml代码

1. <span style="font-size: small;"><dependency>
2. <groupId>org.apache.struts</groupId>
3. <artifactId>struts2-convention-plugin</artifactId>
4. <version>2.2.3</version>
5. </dependency>
6. <dependency>
7. <groupId>org.apache.struts</groupId>
8. <artifactId>struts2-rest-plugin</artifactId>
9. <version>2.2.3</version>
10. </dependency></span>

 <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

Java代码

1. <span style="font-size: small;">package com.st.web;
3. import java.io.Serializable;
5. import org.apache.struts2.rest.HttpHeaders;
7. import com.opensymphony.xwork2.ModelDriven;
8. import com.opensymphony.xwork2.Preparable;
10. public abstractclass BaseController<T> implements ModelDriven<T>,
11. Serializable, Preparable {
12. private staticfinal long serialVersionUID = 7449478681110941532L;
13. protected T entity;
15. /**
16. * GET: /{model}
17. */
18. public abstract HttpHeaders index();
20. /**
21. * POST: /{model}
22. */
23. public abstract HttpHeaders create();
25. /**
26. * PUT: /{model}/{id}
27. */
28. public abstract String update();
30. /**
31. * DELETE: /{model}/{id}
32. */
33. public abstract String destroy();
35. /**
36. * GET: /{model}/{id}
37. */
38. public abstract HttpHeaders show();
40. /**
41. * GET: /{model}/{id}/edit
42. */
43. public abstract String edit();
45. /**
46. * GET: /{model}/new
47. */
48. public abstract String editNew();
50. @Override
51. public T getModel() {
52. return entity;
53. }
55. /**
56. * 子类通过重写此方法初始化实体类
57. */
58. @Override
59. public abstractvoid prepare();
60. }
61. </span>

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

Java代码

1. package com.st.web;
3. import java.util.Date;
4. import java.util.List;
6. import org.apache.struts2.convention.annotation.Result;
7. import org.apache.struts2.convention.annotation.Results;
8. import org.apache.struts2.rest.DefaultHttpHeaders;
9. import org.apache.struts2.rest.HttpHeaders;
11. import com.st.entity.User;
12. import com.st.service.UserService;
14. @Results( { @Result(name ="success", type = "redirectAction", params = {
15. "actionName", "user" }) })
16. public class UserControllerextends BaseController<User> {
17. private staticfinal long serialVersionUID = -2697052455833496406L;
18. private UserService userService;
19. private List<User> list;
20. private Long id;
22. public HttpHeaders create() {
23. entity.setCreateTime(new Date());
24. userService.save(entity);
25. return new DefaultHttpHeaders("success");
26. }
28. public String destroy() {
29. userService.delete(entity.getId());
30. return "success";
31. }
33. public String edit() {
34. return "edit";
35. }
37. public String editNew() {
38. entity = new User();
39. return "editNew";
40. }
42. public HttpHeaders index() {
43. list = userService.list();
44. return new DefaultHttpHeaders("index").disableCaching();
45. }
47. public HttpHeaders show() {
48. return new DefaultHttpHeaders("show");
49. }
51. public String update() {
52. userService.save(entity);
53. return "success";
54. }
56. public void setUserService(UserService userService) {
57. this.userService = userService;
58. }
60. public UserService getUserService() {
61. return userService;
62. }
64. @Override
65. public User getModel() {
66. return entity;
67. }
69. public void setId(Long id) {
70. if (null != id) {
71. System.out.println("id:" + id);
72. entity = userService.get(id);
73. } else {
74. this.id = id;
75. }
76. }
78. public Long getId() {
79. return id;
80. }
82. public List<User> getList() {
83. return list;
84. }
86. public void setList(List<User> list) {
87. this.list = list;
88. }
90. @Override
91. public void prepare() {
92. entity = new User();
93. }
94. }

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

Html代码

1. <%@ page language="java"import="java.util.*"pageEncoding="UTF-8"%>
2. <%@ taglib uri="/struts-tags"prefix="s" %>
3. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
4. <html>
5. <head>
6. <title>User</title>
7. </head>
9. <body>
10. <a href="">List</a>
11. <a href="user/new">Add User</a>
13. <table border="0">
14. <tr>
15. <td width="100">Login Name</td>
16. <td width="120">Password</td>
17. <td width="100">Create Time</td>
18. <td width="80">Manage</td>
19. </tr>
20. <s:iteratorvalue="list"id="u">
21. <tr>
22. <td><s:propertyvalue="#u.loginName"/></td>
23. <td><s:propertyvalue="#u.password"/></td>
24. <td><s:dateformat="yyyy-MM-dd HH:mm"name="#u.createTime"/></td>
25. <td>
26. <a href="user/${u.id }/edit">Edit</a>
27. <span>|</span>
28. <a href="user/${u.id}?_method=DELETE">Delete</a>
29. </td>
30. </tr>
31. </s:iterator>
32. </table>
33. </body>
34. </html>

<%@ 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

Html代码

1. <%@ page contentType="text/html; charset=UTF-8"language="java"import="java.util.*"pageEncoding="UTF-8"%>
2. <%@ taglib uri="/struts-tags"prefix="s" %>
3. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
4. <html>
5. <head>
6. <title>User</title>
7. <meta http-equiv="Content-Type"content="text/html; charset=UTF-8"/>
8. </head>
10. <body>
11. <s:form action="%{#request.contextPath}/user"theme="simple"method="post">
12. <table>
13. <tr>
14. <td>Login Name:<s:textfieldname="loginName"/></td>
15. </tr>
16. <tr>
17. <td>Password:<s:passwordname="password"/></td>
18. </tr>
19. <tr>
20. <td><s:submitvalue="Submit"/><s:resetvalue="Cancel"onclick="history.back()"/></td>
21. </tr>
22. </table>
23. </s:form>
24. </body>
25. </html>

<%@ 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

Html代码

1. <%@ page contentType="text/html; charset=UTF-8"language="java"import="java.util.*"pageEncoding="UTF-8"%>
2. <%@ taglib uri="/struts-tags"prefix="s" %>
3. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
4. <html>
5. <head>
6. <title>User</title>
7. <meta http-equiv="Content-Type"content="text/html; charset=UTF-8"/>
8. </head>
10. <body>
11. <s:form action="%{#request.contextPath}/user/%{id}"theme="simple"method="post">
12. <s:hidden name="_method"value="put"/>
13. <table>
14. <tr>
15. <td>ID:<s:textfieldname="id"disabled="true"/></td>
16. </tr>
17. <tr>
18. <td>Login Name:<s:textfieldname="loginName"/></td>
19. </tr>
20. <tr>
21. <td>Password:<s:passwordname="password"/></td>
22. </tr>
23. <tr>
24. <td><s:submitvalue="Submit"/><s:resetvalue="Cancel"onclick="history.back()"/></td>
25. </tr>
26. </table>
27. </s:form>
28. </body>
29. </html> 

//注意需要将web.xml中struts2的url-pattern改为<url-pattern>/*</url-pattern> ，不能是<url-pattern>*.action</url-pattern>