OSCache 缓存对象（一）

参考：
http://www.klstudio.com/post/123.html

一. 创建需要缓存的对象

package com.zxf.object;

public class News {
	String id;
	String message;

	public News() {
		super();
	}

	public News(String id) {
		super();
		this.id = id;
	}

	public String getId() {
		return id;
	}

	public void setId(String id) {
		this.id = id;
	}

	public String getMessage() {
		return message;
	}

	public void setMessage(String message) {
		this.message = message;
	}

}

二. 创建基础缓存类

package com.zxf.oscache;

import java.util.Date;

import com.opensymphony.oscache.base.NeedsRefreshException;
import com.opensymphony.oscache.general.GeneralCacheAdministrator;

public class BaseCache extends GeneralCacheAdministrator {
	// 过期时间(单位为秒);
	private int refreshPeriod;
	// 关键字前缀字符;
	private String keyPrefix;

	private static final long serialVersionUID = -4397192926052141162L;

	public BaseCache(String keyPrefix, int refreshPeriod) {
		super();
		this.keyPrefix = keyPrefix;
		this.refreshPeriod = refreshPeriod;
	}

	// 添加被缓存的对象;
	public void put(String key, Object value) {
		this.putInCache(this.keyPrefix + "_" + key, value);
	}

	// 删除被缓存的对象;
	public void remove(String key) {
		this.flushEntry(this.keyPrefix + "_" + key);
	}

	// 删除所有被缓存的对象;
	public void removeAll(Date date) {
		this.flushAll(date);
	}

	public void removeAll() {
		this.flushAll();
	}

	// 获取被缓存的对象;
	public Object get(String key) throws Exception {
		try {
			return this.getFromCache(this.keyPrefix + "_" + key,
					this.refreshPeriod);
		} catch (NeedsRefreshException e) {
			this.cancelUpdate(this.keyPrefix + "_" + key);
			throw e;
		}

	}

}

三. 创建cache管理类

package com.zxf.oscache;

import com.zxf.object.News;

public class CacheManager {

	private BaseCache newCache;

	private static CacheManager instance;
	private static Object lock = new Object();

	public CacheManager() {
		// 这个根据配置文件来，初始BaseCache而已,测试用10秒就过期
		newCache = new BaseCache("new", 10);
	}

	public static CacheManager getInstance() {
		if (instance == null) {
			synchronized (lock) {
				if (instance == null) {
					instance = new CacheManager();
				}
			}
		}
		return instance;
	}

	public void putnew(News news) {
		// TODO 自动生成方法存根
		newCache.put(news.getId(), news);
	}

	public void removenew(String newID) {
		// TODO 自动生成方法存根
		newCache.remove(newID);
	}

	public News getnew(String id) {
		// TODO 自动生成方法存根
		try {
			return (News) newCache.get(id);
		} catch (Exception e) {
			// TODO 自动生成 catch 块
			System.out.println("getnew>>newID[" + id + "]>>" + e.getMessage());
			News news = new News(id);
			this.putnew(news);
			return news;
		}
	}

	public void removeAllnew() {
		// TODO 自动生成方法存根
		newCache.removeAll();
	}

}

四. 最后创建两个servlet 运行例子

package com.zxf.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zxf.object.News;
import com.zxf.oscache.CacheManager;

/**
 * 刷新oscache
 */
public class FlushNews extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public FlushNews() {
		super();
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {

		CacheManager cache = CacheManager.getInstance();
		News news = new News();
		news.setId("123");
		news.setMessage("Oscache test.");
		cache.putnew(news);

		response.getWriter().print("flush news success~~~");
		response.flushBuffer();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		this.doGet(request, response);
	}

}

package com.zxf.servlet;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.zxf.object.News;
import com.zxf.oscache.CacheManager;

/**
 * 刷新oscache
 */
public class PublishNews extends HttpServlet {
	private static final long serialVersionUID = 1L;

	/**
	 * @see HttpServlet#HttpServlet()
	 */
	public PublishNews() {
		super();
	}

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doGet(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {

		CacheManager cache = CacheManager.getInstance();
		News getnew = cache.getnew("123");
		StringBuilder sb = new StringBuilder();
		sb.append("<table>");
		sb.append("<tr>");
		sb.append("<td>");
		sb.append("new's id");
		sb.append("</td>");
		sb.append("<td>");
		sb.append(getnew.getId());
		sb.append("</td>");
		sb.append("</tr>");
		sb.append("<tr>");
		sb.append("<td>");
		sb.append("new's message");
		sb.append("</td>");
		sb.append("<td>");
		sb.append(getnew.getMessage());
		sb.append("</td>");
		sb.append("</tr>");
		sb.append("</table>");
		response.getWriter().print(sb.toString());
		response.flushBuffer();
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse
	 *      response)
	 */
	protected void doPost(HttpServletRequest request,
			HttpServletResponse response) throws ServletException, IOException {
		this.doGet(request, response);
	}

}

附上servlet配置文件web.xml

<servlet>
		<description></description>
		<display-name>FlushNews</display-name>
		<servlet-name>FlushNews</servlet-name>
		<servlet-class>com.zxf.servlet.FlushNews</servlet-class>
	</servlet>
	<servlet>
		<description></description>
		<display-name>PublishNews</display-name>
		<servlet-name>PublishNews</servlet-name>
		<servlet-class>com.zxf.servlet.PublishNews</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>FlushNews</servlet-name>
		<url-pattern>/FlushNews</url-pattern>
	</servlet-mapping>
	<servlet-mapping>
		<servlet-name>PublishNews</servlet-name>
		<url-pattern>/PublishNews</url-pattern>
	</servlet-mapping>