Create Monitor.java

监控线程，监控远程词典的更新

src/main/java/org/wltea/analyzer/dic/Monitor.java

+package org.wltea.analyzer.dic;
+
+import java.io.IOException;
+
+import org.apache.http.Header;
+import org.apache.http.client.ClientProtocolException;
+import org.apache.http.client.config.RequestConfig;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpHead;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClients;
+import org.wltea.analyzer.help.Sleep;
+import org.wltea.analyzer.help.Sleep.Type;
+
+public class Monitor implements Runnable {
+	
+	private static CloseableHttpClient httpclient = HttpClients.createDefault();
+	/*
+	 * 上次更改时间
+	 */
+	private String last_modified;
+	/*
+	 * 资源属性
+	 */
+	private String eTags;
+	
+	/*
+	 * 请求地址
+	 */
+	private String location; 
+	
+	public Monitor(String location) {
+		this.location = location;
+		this.last_modified = null;
+		this.eTags = null;
+	}
+	/**
+	 * 监控流程：
+	 *  ①向词库服务器发送Head请求
+	 *  ②从响应中获取Last-Modify、ETags字段值，判断是否变化
+	 *  ③如果未变化，休眠1min，返回第①步
+	 * 	④如果有变化，重新加载词典
+	 *  ⑤休眠1min，返回第①步
+	 */
+	
+	public void run() {
+		//超时设置
+		RequestConfig rc = RequestConfig.custom().setConnectionRequestTimeout(10*1000)
+				.setConnectTimeout(10*1000).setSocketTimeout(15*1000).build();
+		while (true) {
+			HttpHead head = new HttpHead(location);
+			head.setConfig(rc);
+			
+			//设置请求头
+			if (last_modified != null) {
+				head.setHeader("If-Modified-Since", last_modified);
+			}
+			if (eTags != null) {
+				head.setHeader("If-None-Match", eTags);
+			}
+			
+			CloseableHttpResponse response = null;
+			try {
+				response = httpclient.execute(head);
+				
+				//返回304 Not Modified，词库未更新
+				if(response.getStatusLine().getStatusCode()==304){
+					continue;
+				}else if(response.getStatusLine().getStatusCode()==200){
+				
+					if (!response.getLastHeader("Last-Modified").getValue().equalsIgnoreCase(last_modified)
+						||!response.getLastHeader("ETags").getValue().equalsIgnoreCase(eTags)) {
+	
+						// 远程词库有更新,需要重新加载词典，并修改last_modified,eTags
+						Dictionary.getSingleton().reLoadMainDict();
+						last_modified = response.getLastHeader("Last-Modified")==null?null:response.getLastHeader("Last-Modified").getValue();
+						eTags = response.getLastHeader("ETags")==null?null:response.getLastHeader("ETags").getValue();
+					}
+				}
+				
+			} catch (ClientProtocolException e) {
+				e.printStackTrace();
+			} catch (IOException e) {
+				e.printStackTrace();
+			}finally{
+				try {
+					response.close();
+				} catch (IOException e) {
+					e.printStackTrace();
+				}
+				Sleep.sleep(Type.SEC, 60);
+			}
+		}	
+	}
+	
+}