75 lines
1.8 KiB
Java
75 lines
1.8 KiB
Java
package cache;
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import common.LogLevel;
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import common.Logger;
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import java.io.IOException;
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import java.io.InputStream;
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import java.util.Properties;
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public class ProblemsCachManager {
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private boolean update = false;
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private BaseCache cache;
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private static ProblemsCachManager instance;
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private static Object lock = new Object();
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private static Logger logger=Logger.getInstance();
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private ProblemsCachManager() {
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// 这个根据配置文件来，初始BaseCache而已;
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Properties prop = new Properties();
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InputStream in = ProblemsCachManager.class
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.getResourceAsStream("cache.properties");
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try {
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prop.load(in);
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String validTime = prop.getProperty("problemsValidTime").trim();
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cache = new BaseCache("Problems", Integer.parseInt(validTime));
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} catch (IOException e) {
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e.printStackTrace();
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}
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}
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public static ProblemsCachManager getInstance() {
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if (instance == null) {
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synchronized (lock) {
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if (instance == null) {
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instance = new ProblemsCachManager();
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}
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}
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}
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return instance;
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}
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public void putObject(String key, Object value) { // key以classId_examId
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logger.log("已放入缓存"+key, LogLevel.INFO);
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cache.put(key, value);
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}
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public void removeObject(String key) {
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logger.log("已移除缓存"+key, LogLevel.INFO);
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cache.remove(key);
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}
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public void removeAllObject() {
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cache.removeAll();
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}
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public Object getObject(String key) {
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try {
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// 从Cache中获得
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return cache.get(key);
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} catch (Exception e) {
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logger.log("获取缓存出错:"+key+"e:"+e.getMessage(), LogLevel.ERROR);
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// Cache中没有则从DB库获取
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// 数据库中读取数据
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// 把获取的对象再次存入Cache中
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this.putObject(key, null);
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update = true;
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return null;
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} finally {
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if (!update) {
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// 如果Cache中的内容更新出现异常，则终止该方法
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cache.cancelUpdate(key); // 取消对id的更新
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}
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}
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}
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}
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