java缓存技术memcached实例
1 下载memcached-1.2.1-win32.zip? 并且解压.
2 新建web project项目 名字自己取,然后导入必要的包,alisoft-xplatform-asf-cache-2.5.1.jar,commons-logging-1.0.3.jar,log4j-1.2.13.jar
3 新建类 user.java
package bean;
import java.io.Serializable;
public class User implements Serializable{
?
??? /**
???? * 序列号
???? */
??? private static final long serialVersionUID = -3896605600471191953L;
??? private int uid;
??? private String uname;
??? private String upass;
???
??? public int getUid() {
?????? return uid;
??? }
??? public void setUid(int uid) {
?????? this.uid = uid;
??? }
??? public String getUname() {
?????? return uname;
??? }
??? public void setUname(String uname) {
?????? this.uname = uname;
??? }
??? public String getUpass() {
?????? return upass;
??? }
??? public void setUpass(String upass) {
?????? this.upass = upass;
??? }
}
4 新建 JdbcConnector.java
package util;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
public class JdbcConnector {
? // 定义数据库连接常量
??? private final static String DRIVER = "com.mysql.jdbc.Driver";
??? private final static String URL = "jdbc:mysql://192.168.1.13:3306/test";
??? private final static String DBNAME = "root";
??? private final static String DBPASS = "123456";
???
??? /**
???? * 得到数据库连接
???? * @return
???? * @throws ClassNotFoundException
???? * @throws SQLException
???? */
??? public Connection getConn()throws ClassNotFoundException,SQLException {
?????? // 加载驱动
?????? Class.forName(DRIVER);
?????? // 通过DriverManager对象得到连接
?????? Connection conn = DriverManager.getConnection(URL,DBNAME,DBPASS);
?????? // 返回数据库连接
?????? return conn;
??? }
}
5 新建 UserDao.java
package util;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import bean.User;
import com.mysql.jdbc.Connection;
import com.mysql.jdbc.PreparedStatement;
import com.mysql.jdbc.ResultSet;
public class UserDao extends JdbcConnector {
??? // 定义全局变量
??? Connection conn = null;
??? PreparedStatement pstmt = null;
??? ResultSet rs = null;
???
??? /**
???? * 根据Id查询用户
???? * @param uid
???? * @return
???? */
??? public User getUserById(int uid) {
?????? // 创建User对象
?????? User user = null;
?????? // 创建SQL语句
?????? String sql = "select * from user where uid=?";
??????
?????? try {
?????????? // 获得数据库连接
?????????? conn = (Connection) this.getConn();
?????????? // 通过Connection对象创建PrepareStatement对象
?????????? pstmt = (PreparedStatement) conn.prepareStatement(sql);
?????????? // 设置SQL语句的参数
?????????? pstmt.setInt(2, uid);
?????????? // 执行查询，将查询结果赋给ResultSet对象
?????????? rs = (ResultSet) pstmt.executeQuery();
?????????? // 遍历指针
?????????? while (rs.next())
?????????? {
????????????? user = new User();
????????????? user.setUid(rs.getInt("uid"));
????????????? user.setUname(rs.getString("uname"));
????????????? user.setUpass(rs.getString("upass"));
?????????? }
?????? } catch (ClassNotFoundException e) {
?????????? e.printStackTrace();
?????? } catch (SQLException e) {
?????????? e.printStackTrace();
?????? }
?????? return user;
??? }
???
??? /**
???? * 查询所有用户
???? * @return
???? */
??? @SuppressWarnings("unchecked")
??? public List getUserList() {
?????? // 创建ArrayList对象
?????? List userList = new ArrayList();
??????
?????? // 创建SQL对象
?????? String sql = "select * from user";
??????
?????? try {
?????????? conn = (Connection) this.getConn();
?????????? pstmt = (PreparedStatement) conn.prepareStatement(sql);
?????????? rs = (ResultSet) pstmt.executeQuery();
?????????? while (rs.next())
?????????? {
????????????? User user = new User();
????????????? user.setUid(rs.getInt("uid"));
????????????? user.setUname(rs.getString("uname"));
????????????? user.setUpass(rs.getString("upass"));
?????????????
????????????? userList.add(user);
?????????? }
?????? } catch (ClassNotFoundException e) {
?????????? e.printStackTrace();
?????? } catch (SQLException e) {
?????????? e.printStackTrace();
?????? }
?????? return userList;
??? }
}
6 新建 MemcachedManager.java
package memcachedTest;
import java.util.Date;
import java.util.List;
import util.UserDao;
import bean.User;
import com.alisoft.xplatform.asf.cache.memcached.client.MemCachedClient;
import com.alisoft.xplatform.asf.cache.memcached.client.SockIOPool;
public class MemcachedManager {
?
?? // 创建MemCachedClient全局对象
??? private static MemCachedClient mcc = new MemCachedClient();
???
??? static {
?????? // 创建服务器列表及其权重
?????? String[] servers = {"127.0.0.1:11211"};
?????? Integer[] weights = {3};
??????
?????? // 创建Socket连接池对象
?????? SockIOPool pool = SockIOPool.getInstance();
??????
?????? // 设置服务器信息
?????? pool.setServers(servers);
?????? pool.setWeights(weights);
?????? pool.setFailover(true);
??????
?????? // 设置初始连接数、最小和最大连接数以及最大处理时间
?????? pool.setInitConn(5);
?????? pool.setMinConn(5);
?????? pool.setMaxConn(250);
?????? pool.setMaxIdle(1000*60*60*6);
??????
?????? // 设置主线程睡眠时间
?????? pool.setMaintSleep(30);
??????
?????? // 设置TCP参数、连接超时等
?????? pool.setNagle(false);
?????? pool.setSocketTO(3000);
?????? pool.setSocketConnectTO(0);
?????? pool.setAliveCheck(true);
??????
?????? // 初始化连接池
?????? pool.initialize();
??????
?????? // 压缩设置，超过指定大小（单位为K）的数据都会被压缩
?????? mcc.setCompressEnable(true);
?????? mcc.setCompressThreshold(64 * 1024);
??? }
???
??? /**
???? * 无参构造
???? */
??? protected MemcachedManager (){
??????
??? }
???
??? // 受保护的对象
??? protected static MemcachedManager instance = new MemcachedManager();
???
??? /**
???? * 为受保护的对象提供一个公共的访问方法
???? */
??? public static MemcachedManager getInstance () {
?????? return instance;
??? }
???
??? /**
???? * 添加对象到缓存中，构成方法重载
???? * @param key
???? * @param value
???? * @return
???? */
??? public boolean add(String key,Object value) {
?????? return mcc.add(key, value);
??? }
??? public boolean add (String key,Object value,Date expiry) {
?????? return mcc.add(key, value,expiry);
??? }
???
??? public boolean replace (String key,Object value) {
?????? return mcc.replace(key, value);
??? }
???
??? public boolean replace (String key,Object value,Date expiry)
??? {
?????? return mcc.replace(key, value, expiry);
??? }
???
??? /**
???? * 根据指定的关键字获取对象
???? */
??? public Object get(String key) {
?????? return mcc.get(key);
??? }
???
???
???
??? /**
???? * 利用MemCached测试将单个对象存入缓存，并从缓存中取出
???? */
//? public static void main(String[] args) {
//????? // 得到MemcachedManager实例
//???? MemcachedManager cache = MemcachedManager.getInstance();
//????
//???? // 创建UserDao对象
//???? UserDao userDao = new UserDao();
//???? // 查询单个User对象
//???? User user = userDao.getUserById(4);
//????
//???? // 将User对象添加到缓存中
//???? cache.add("user", user.getUname());
//????
//???? // 将User对象从缓存中取出来
//???? String uname = (String)cache.get("user");
//????
//???? System.out.println("从缓存中取出的对象为：" + uname);
//? }
???
???
???
??? /**
???? * 利用MemCached对象将集合存入缓存，并从缓存中取出
???? */
??? @SuppressWarnings({ "unchecked", "rawtypes" })
??? public static void main(String[] args) {
?????? // 得到MemcachedManager实例
?????? MemcachedManager cache = MemcachedManager.getInstance();
??????
?????? // 创建UserDao对象
?????? UserDao userDao = new UserDao();
?????? // 得到集合对象
?????? List userList = userDao.getUserList();
??????
?????? // 创建User对象
?????? User user = null;
?????? for (int i=0; i<userList.size(); i++)
?????? {
?????????? // 循环遍历集合对象
?????????? user = (User)userList.get(i);
?????????? user.getUid();
?????????? user.getUname();
?????????? user.getUpass();
??????????
?????????? // 将集合对象存入缓存中
?????????? cache.add("userList" + i,user.getUname());
??????????
?????????? // 将集合从缓存中取出
?????????? String uname = (String)cache.get("userList"+i);
??????????
?????????? System.out.println("从缓存中取得的集合为：" + uname);
?????? }
??? }
}
?
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结果从控制台输出:
从缓存中取得的集合为：uname
从缓存中取得的集合为：uname1
从缓存中取得的集合为：uname2
从缓存中取得的集合为：uname3
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