java - 获取一个对象并将其导出到其类之外

Question

我有这个类，我想导出到它的外部(到另一个类)，在其中创建的对象httpdStatistics stats。哪种方法是实现此目的的最佳方法？

package org.w3c.jigsaw.status ;

import java.util.Date;

import org.w3c.tools.resources.Attribute;
import org.w3c.tools.resources.AttributeHolder;
import org.w3c.tools.resources.AttributeRegistry;
import org.w3c.tools.resources.FramedResource;
import org.w3c.tools.resources.IntegerAttribute;
import org.w3c.tools.resources.Resource;

import org.w3c.tools.resources.store.ResourceStoreManager;

import org.w3c.www.http.HTTP;
import org.w3c.www.http.HttpMessage;

import org.w3c.jigsaw.frames.HTTPFrame;

import org.w3c.jigsaw.http.Reply;
import org.w3c.jigsaw.http.Request;
import org.w3c.jigsaw.http.httpd;
import org.w3c.jigsaw.http.httpdStatistics;

import org.w3c.jigsaw.html.HtmlGenerator;

/**
 * This class exports the server statistics.
 * It makes available a bunch of various parameters about the current
 * server, and uses the Refresh meta-tag (as the ThreadStat) to 
 * make them redisplay.
 * <p>This would benefit from being an applet.
 */

public class StatisticsFrame extends HTTPFrame {
    private static int REFRESH_DEFAULT = 5;

    /**
     * Attribute index - Our refresh interval.
     */
    protected static int ATTR_REFRESH = -1 ;

    static {
    Attribute a   = null ;
    Class     cls = null ;
    try {
        cls = Class.forName("org.w3c.jigsaw.status.StatisticsFrame");
    } catch (Exception ex) {
        ex.printStackTrace() ;
        System.exit(1) ;
    }
    // The refresh interval attribute:
    a = new IntegerAttribute("refresh"
                 , new Integer(5)
                 , Attribute.EDITABLE) ;
    ATTR_REFRESH = AttributeRegistry.registerAttribute(cls, a) ;
    }

    static String time_tbl = ("<table border=\"1\" class=\"time\">"
                  + "<caption>Request processing times"
                  + "</caption><tr>"
                  + "<th>min"
                  + "<th>avg"
                  + "<th>max"
                  + "</tr><tr>") ;

    static String dyn_time_tbl = ("<table border=\"1\" class=\"time\">"
                  + "<caption>Dynamic request processing times"
                  + "</caption><tr>"
                  + "<th>min"
                  + "<th>avg"
                  + "<th>max"
                  + "</tr><tr>") ;

    static String sta_time_tbl = ("<table border=\"1\" class=\"time\">"
                  + "<caption>Static request processing times"
                  + "</caption><tr>"
                  + "<th>min"
                  + "<th>avg"
                  + "<th>max"
                  + "</tr><tr>") ;

    public void registerResource(FramedResource resource) {
    super.registerOtherResource(resource);
    }

    /**
     * Get the current set of statistics.
     * Display the collected statistics in an HTML table.
     * @param request The request to process.
     */

    public Reply get (Request request) {
    HtmlGenerator g = new HtmlGenerator("Statistics") ;
    int refresh = getInt(ATTR_REFRESH, REFRESH_DEFAULT);
    if (refresh > 0) {
        g.addMeta("Refresh", Integer.toString(refresh));
    }
    addStyleSheet(g);
    // Dump the statistics:
    httpdStatistics stats = ((httpd)getServer()).getStatistics() ;
    // Uptime:
    g.append("<h1>Server Statistics</h1>");
    long start_time = stats.getStartTime();
    long uptime     = (System.currentTimeMillis() - start_time) / 1000;
    g.append("<p>Your server was started on <span class=\"date\">");
    g.append(new Date(start_time).toString());
    long duptime = uptime / (3600L*24L);
    long htemp   = uptime % (3600L*24L);
    long huptime = htemp / 3600L;
    long mtemp   = htemp % 3600L;
    long muptime = mtemp / 60L;
    long suptime = mtemp % 60L;
    g.append("</span>\n<p>It has now been running for <span "+
         "class=\"uptime\">");
    g.append(Long.toString(duptime));
    g.append(" days, ");
    g.append(Long.toString(huptime));
    g.append(" hours, ");
    g.append(Long.toString(muptime));
    g.append(" minutes and ");
    g.append(Long.toString(suptime));
    g.append(" seconds.</span>\n");
    // Hits and bytes:
    long  nb_hits      = stats.getHitCount();
    long  dyn_hits     = stats.getDynamicHitCount();
    long  static_hits  = stats.getStaticHitCount();
    float static_pcent = 0;
    float dyn_pcent    = 0;
    if (nb_hits > 0) {
        static_pcent = ((float) static_hits / (float) nb_hits) * 100;
        dyn_pcent = ((float) dyn_hits / (float) nb_hits) * 100;
    }
    g.append("<ul><li>hits: ", Long.toString(nb_hits));
    g.append("  <ul>\n    <li>static: ",Long.toString(static_hits));
    g.append(" (", Float.toString(static_pcent));
    g.append("%)</li>\n    <li>dynamic: ", Long.toString(dyn_hits));
    g.append(" (", Float.toString(dyn_pcent));
    g.append("%)</li>\n  </ul>\n");
    long bytes = stats.getEmittedBytes();
    long kbytes = bytes / 1024;
    long mbytes = kbytes / 1024;
    long gbytes = mbytes / 1024;
        long tbytes = gbytes / 1024;
    if (tbytes != 0) {
        g.append("</li>\n<li>bytes: ", Long.toString( tbytes),"TB, ");
        g.append(Long.toString(gbytes % 1024), "GB, ");
        g.append(Long.toString(mbytes % 1024), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(bytes % 1024));
    } else if (gbytes != 0) {
        g.append("</li>\n<li>bytes: ", Long.toString(gbytes), "GB, ");
        g.append(Long.toString(mbytes % 1024), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(bytes % 1024));
    } else if (mbytes != 0) {
        g.append("</li>\n<li>bytes: ", Long.toString(mbytes), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(bytes % 1024));
    } else if (kbytes != 0) {
        g.append("</li>\n<li>bytes: ", Long.toString(kbytes), "KB, ");
        g.append(Long.toString(bytes % 1024));
    } else {
        g.append("</li>\n<li>bytes: ", Long.toString(bytes));
    }
    // avg hit/sec
    float avghits = 0;
    float avghitsday = 0;
    if (uptime > 0) {
        avghits = ((float) nb_hits) / ((float) uptime);
        avghitsday = ((float) nb_hits * 86400) / ((float) uptime); 
    }
    g.append("</li>\n<li>Average hits per second: ");
    g.append(Float.toString(avghits));
    g.append("</li>\n<li>Average hits per day: ");
    g.append(Integer.toString((int) avghitsday));
    // avg bytes/hit
    long avgbph;

    if (nb_hits > 0) {
        avgbph = bytes / nb_hits;
    } else {
        avgbph = 0;
    }
    kbytes = avgbph / 1024;
    mbytes = kbytes / 1024;
    gbytes = mbytes / 1024;
    if (gbytes != 0) {
        g.append("</li>\n<li>Average bytes per hit: ");
        g.append(Long.toString(gbytes), "GB, ");
        g.append(Long.toString(mbytes % 1024), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(avgbph % 1024));
    } else if (mbytes != 0) {
        g.append("</li>\n<li>Average bytes per hit: ");
        g.append(Long.toString(mbytes), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(avgbph % 1024));     
    } else if (kbytes != 0) {
        g.append("</li>\n<li>Average bytes per hit: ");
        g.append(Long.toString(kbytes), "KB, ");
        g.append(Long.toString(avgbph % 1024));
    } else {
        g.append("</li>\n<li>Average bytes per hit: ",
             Long.toString(avgbph));
    }
    // avg throughput
    long avgbps = 0;
    if (uptime > 0) {
        avgbps = bytes / uptime;
    }
    kbytes = avgbps / 1024;
    mbytes = kbytes / 1024;
    gbytes = mbytes / 1024;
    if (gbytes != 0) {
        g.append("</li>\n<li>Average bytes per second: ");
        g.append(Long.toString(gbytes),  "GB, ");
        g.append(Long.toString(mbytes % 1024), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(avgbps % 1024));
    } else if (mbytes != 0) {
        g.append("</li>\n<li>Average bytes per second: ");
        g.append(Long.toString(mbytes), "MB, ");
        g.append(Long.toString(kbytes % 1024), "KB, ");
        g.append(Long.toString(avgbps % 1024));
    } else if (kbytes != 0) {
        g.append("</li>\n<li>Average bytes per second: ");
        g.append(Long.toString(kbytes), "KB, ");
        g.append(Long.toString(avgbps % 1024));
    } else {
        g.append("</li>\n<li>Average bytes per second: ", 
             Long.toString(avgbps));
    }    
    g.append("</li>\n</ul>");
    // Request times:
    g.append(time_tbl) ;
    g.append("<td>"
         , Long.toString(stats.getMinRequestTime())
         , " <span class=\"unit\">ms</span>") ;
    g.append("</td>\n<td>"
         , Long.toString(stats.getMeanRequestTime())
         , " <span class=\"unit\">ms</span>") ;
    g.append("</td>\n<td>"
         , Long.toString(stats.getMaxRequestTime())
         , " <span class=\"unit\">ms</span>") ;
    g.append("</td>\n</table>\n") ;

    // static
    if (static_hits>0) {
        g.append(sta_time_tbl) ;
        g.append("<td>"
             , Long.toString(stats.getMinStaticRequestTime())
             , " <span class=\"unit\">ms</span>") ;
        g.append("</td>\n<td>"
             , Long.toString(stats.getMeanStaticRequestTime())
             , " <span class=\"unit\">ms</span>") ;
        g.append("</td>\n<td>"
             , Long.toString(stats.getMaxStaticRequestTime())
             , " <span class=\"unit\">ms</span>") ;
        g.append("</td>\n</table>\n") ;
    }

    // dynamic 
    if (dyn_hits>0) {
        g.append(dyn_time_tbl) ;
        g.append("<td>"
             , Long.toString(stats.getMinDynamicRequestTime())
             , " <span class=\"unit\">ms</span>") ;
        g.append("</td>\n<td>"
             , Long.toString(stats.getMeanDynamicRequestTime())
             , " <span class=\"unit\">ms</span>") ;
        g.append("</td>\n<td>"
             , Long.toString(stats.getMaxDynamicRequestTime())
             , " <span class=\"unit\">ms</span>") ;
        g.append("</td>\n</table>\n") ;
    }

    // Get Server internal Stats
    try {
        g.append(((httpd)getServer()).getHTMLStatus());
    } catch (Exception ex) {
        ex.printStackTrace();
    }
    Reply reply = request.makeReply(HTTP.OK) ;
    reply.setNoCache();
    reply.setStream (g) ;
    reply.setDynamic(true);
    return reply ;
    }
}

Answer 1

现在看来您已经将 httpdStatistics 中的所有数据提取到 HtmlGenerator 对象中，然后使用它来构建 Reply。您还希望使 httpdStatistics 对象本身可以从此类外部访问，对吗？

我不知道 getServer().getStatistics() 内部发生了什么，但是您可以添加一个返回该值的“getter”方法吗？然后，您还可以在 get() 内部使用 getter，以避免代码重复。像这样的东西:

public httpdStatistics getStats() {
  return ((httpd)getServer()).getStatistics();
}

在get()中:

httpdStatistics stats = getStats();