cachedefinition.java

来自「spring+acegi编写的网上书城」· Java 代码 · 共 99 行

package net.livebookstore.web.filter;

import java.util.HashMap;
import java.util.Map;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Define pages to be cached. Using following syntax:<br/>
 * <code>url=param1, param2 defaultValue, param3, ...</code><br/>
 * For example, for url /listBooks.jsp?id=xxx&page=xxx, rule is:<br/>
 * <code>/listBooks.jsp=id,page 1</code><br/>
 * Each line for one rule.
 * 
 * @author Xuefeng
 */
public class CacheDefinition {

    private CacheEntry[] entries;

    public CacheDefinition(CacheEntry[] entries) {
        this.entries = entries;
    }

    public String getKey(HttpServletRequest request) {
        for(CacheEntry entry : entries) {
            String s = entry.buildKey(request);
            if(s!=null)
                return s;
        }
        return null;
    }
}

class CacheEntry {

    private String url;
    private Map<String, String> parameters = new HashMap<String, String>();
    private int parametersCount;

    private Log log = LogFactory.getLog(getClass());

    /**
     * Config string, e.g.:
     * /user/test.jspx=id,name,page "1"
     * @param config
     */
    public CacheEntry(String config) {
        log.info("Parse cache config: " + config);
        String[] ss = config.trim().split("\\=");
        if(ss.length!=2)
            throw new IllegalArgumentException("Illegal config: " + config);
        url = ss[0].trim();
        if(url.equals(""))
            throw new IllegalArgumentException("Illegal config: " + config);
        String[] ps = ss[1].split("\\,");
        for(String p : ps)
            addParameter(p);
        parametersCount = parameters.size();
    }

    private void addParameter(String p) {
        p = p.trim();
        String[] ss = p.split("[ ]+", 2);
        String param = ss[0];
        String value = null;
        if(ss.length==2) {
            value = ss[1].trim();
            if(value.matches("\\\".*\\\""))
                value = value.substring(1, value.length()-1);
        }
        parameters.put(param, value);
    }

    public String buildKey(HttpServletRequest request) {
        if(!url.equals(request.getRequestURI()))
            return null;
        if(parametersCount==0)
            return url;
        StringBuffer sb = new StringBuffer(256);
        sb.append(this.url).append('?');
        for(String p : parameters.keySet()) {
            String value = request.getParameter(p);
            if(value!=null)
                sb.append(p).append('=').append(value).append('&');
            else {
                String dv = parameters.get(p);
                if(dv==null)
                    return null;
                sb.append(p).append('=').append(dv).append('&');
            }
        }
        return sb.toString();
    }
}