用到了fastJson用来解析配置,原理是通过自己实现response类来得到输出的内容

复制代码 代码如下:
package saleandbuy.freemodule.web.filter;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

public class CacheResp {
private long waitTime=1000*3;

private static Map<String,CacheInfo> cfgMap=new HashMap<String, CacheResp.CacheInfo>();

public static final String QUERY_STRINGS="queryStrings";
public static final String CACHED_TIME="cachedTime";
public static final String CACHE_CONFIG="cacheConfig";

public static void config(String cfgJson) {
JSONObject cfg=JSON.parseObject(cfgJson);
for (Map.Entry<String, Object> entry : cfg.entrySet()) {
String key=entry.getKey();
Map<String, Object> value=(Map<String, Object>) entry.getValue();
List queryStrings= (JSONArray)value.get(QUERY_STRINGS);
Integer cachedTime=(Integer) value.get(CACHED_TIME);
CacheInfo cacheInfo=new CacheInfo(queryStrings,cachedTime);
cfgMap.put(key, cacheInfo);
}
}

public static void cachedDo(HttpServletRequest request, HttpServletResponse response,FilterChain chain) throws IOException, ServletException {
CacheInfo cacheInfo=getCacheInfo(request);
String queryString=request.getQueryString();
//cacheInfo为空则不需要缓存，不为空则需要缓存
if(cacheInfo!=null){
long now=System.currentTimeMillis();
synchronized (CacheResp.class) {
if(now-cacheInfo.lastUpdateTime>cacheInfo.cachedTime){
System.out.println("not use cache:");
ProxyResponse proxyResponse=new ProxyResponse(response);
chain.doFilter(request, proxyResponse);
cacheInfo.cacheMap.put(queryString, proxyResponse.getBuffer());
cacheInfo.lastUpdateTime=now;
}else {
System.out.println("use cache");
}
}
String cacheStr=cacheInfo.cacheMap.get(queryString).toString();
response.getWriter().write(cacheStr);
}else {
chain.doFilter(request, response);
}
}

private static CacheInfo getCacheInfo(HttpServletRequest request){
String key=request.getRequestURI().replace(request.getContextPath(), "");
CacheInfo cacheInfo=cfgMap.get(key);
if(cacheInfo!=null&&
cacheInfo.needCache(request.getQueryString())){
return cacheInfo;
}
return null;
}

public static class CacheInfo{
public List queryStrings=Arrays.asList(new String[]{"list","index"});
public long cachedTime=1000;
public long lastUpdateTime=0;
public Map<String, StringBuffer> cacheMap=new HashMap<String, StringBuffer>();

public CacheInfo(List queryStrings, Integer cachedTime) {
super();
if(cachedTime!=null){
this.cachedTime = cachedTime;
}
this.queryStrings = queryStrings;
}

/**
*
* @param queryStrings request.getQueryString
* @return
*/
public boolean needCache(String queryStrings) {
if(queryStrings==null){//queryStrings为空时默认缓存所有的查询
return true;
}
return queryStrings.contains(queryStrings);
}

}

private static class ProxyResponse extends HttpServletResponseWrapper{

private StringWriter sw=new StringWriter();

//private ByteArrayOutputStream baos=new ByteArrayOutputStream();

public ProxyResponse(HttpServletResponse response) {
super(response);
}

@Override
public PrintWriter getWriter() throws IOException {
return new PrintWriter(sw);
}

public StringBuffer getBuffer() {
return sw.getBuffer();
}
}
}