詳解在Java程序中運(yùn)用Redis緩存對象的方法

<!-- Redis 連接池配置 -->
<bean id="jedisPool" class="redis.clients.jedis.JedisPool"
	destroy-method="close">		
	<constructor-arg name="host" value="127.0.0.1" />
	<constructor-arg name="port" value="6379" />
</bean>

package com.sgxy.util;
 
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import net.sf.json.JSONArray;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
 
@Component
public class RedisUtil {
	@Autowired
	JedisPool pool; // Jedis連接池
	
  // 判斷Redis中是否存在鍵
	public boolean existsKey(String key) {
		Jedis jedis = pool.getResource();
		boolean bool;
		try {
			bool = jedis.exists(key);
		} finally {
			jedis.close();
		}
		return bool;
	}
 
	// 取緩存中的二進(jìn)制數(shù)據(jù)，反序列化成List集合對象
	@SuppressWarnings("unchecked")
	public <T> List<T> getObject(String key, Class<T> clazz) {
		Jedis jedis = pool.getResource();
		// 二進(jìn)制 IO 輸入流
		ByteArrayInputStream is = null;
		ObjectInputStream ois = null;
		try {
			// 從緩存中取二進(jìn)制數(shù)據(jù)
			byte[] b = jedis.get(key.getBytes());
			is = new ByteArrayInputStream(b);
			ois = new ObjectInputStream(is);
			// 把二進(jìn)制轉(zhuǎn)換成T指定類型的集合
			return (List<T>) ois.readObject();
 
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				is.close();
				ois.close();
			} catch (Exception e2) {
				e2.printStackTrace();
			}
			jedis.close();
		}
		return null;
	}
 
	// 把對象序列化二進(jìn)制格式并保證到Redis緩存中
	public void saveObject(Object object, String key) {
		Jedis jedis = pool.getResource();
		// 二進(jìn)制 IO 輸出流
		ByteArrayOutputStream os = null;
		ObjectOutputStream oos = null;
		try {
			os = new ByteArrayOutputStream();
			oos = new ObjectOutputStream(os);
			oos.writeObject(object); // 二進(jìn)制數(shù)據(jù)
			byte[] b = os.toByteArray();
			// 存入二進(jìn)制數(shù)據(jù)到Redis緩存中
			jedis.set(key.getBytes(), b);
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			try {
				os.close();
				oos.close();
			} catch (Exception e2) {
				e2.printStackTrace();
			}
			jedis.close();
		}
	}
 
	// 把List集合對象轉(zhuǎn)換成json格式保存到指定的鍵中
	public void saveJsonArray(Object object, String key) {
		Jedis jedis = pool.getResource();
		try {
			// 格式化成Json字符串
			JSONArray array = JSONArray.fromObject(object);
			jedis.set(key, array.toString()); // 存入緩存
		} finally {
			jedis.close();
		}
	}
 
	// 通過鍵取出Json字符串并轉(zhuǎn)換成 Class<T>這個T所指定的類型
	@SuppressWarnings({ "static-access", "unchecked" })
	public <T> List<T> getJsonArray(String key, Class<T> clazz) {
		Jedis jedis = pool.getResource();
		try {
			String str = jedis.get(key);
			JSONArray array = JSONArray.fromObject(str);
			// 把字符串轉(zhuǎn)換回集合對象 clazz是指定的類型
			return (List<T>) array.toCollection(array, clazz);
		} finally {
			jedis.close();
		}
	}
}

@Controller //注解這個類為控制器
@RequestMapping("grade") //注冊訪問此控制器的URL
public class GradeController {
	@Autowired // 從IOC容器注入業(yè)務(wù)層對象
	GradeService gradeService;
	@Autowired
	JedisPool pool;
	@Autowired
	RedisUtil redisUtil;
 
	@RequestMapping("list") //注冊URL
	public ModelAndView list() { 
		List<Grade> grades = null;
		if (redisUtil.existsKey("g")) {
			System.out.println("從Redis 緩存中取數(shù)據(jù)..");
			//調(diào)用反序列化方法取緩存的數(shù)據(jù)
      grades = redisUtil.getObject("g",Grade.class);			
			
      //調(diào)用Json格式轉(zhuǎn)換的方法取緩存數(shù)據(jù)
      //grades = redisUtil.getJsonArray("gradeList", Grade.class);				
		} else {
			System.out.println("從數(shù)據(jù)庫中取數(shù)據(jù)，并存入緩存..");			
			//調(diào)用底層方法從數(shù)據(jù)庫中取數(shù)據(jù)
      grades = gradeService.find();
 
      //調(diào)用序列化方法把數(shù)據(jù)緩存到Redis中
			redisUtil.saveObject(grades, "g");
 
      //調(diào)用Json格式化方法把數(shù)據(jù)緩存到Redis中
			//redisUtil.saveJsonArray(grades, "gradeList");		 
		}	 
		return new ModelAndView("gradeList", "grades", grades);
	}
}