网站缓存数据到tomcat服务器

通过缓存使相同的数据不用重复加载，降低数据库的访问

public class CacheFilter implements Filter {
  //实例变量【每线程共享】

	private Map<String,byte[]> cache=new HashMap<String , byte[]>();

	@Override
	public void destroy() {

	}

	@Override
	public void doFilter(ServletRequest req, ServletResponse res,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request=(HttpServletRequest) req;
		HttpServletResponse response=(HttpServletResponse) res;
//		1、取得客户端访问路径
		String uri=request.getRequestURI();
//		2、根据URL去缓存中查询对应的页面资源
		byte[] data=cache.get(uri);
//		3、如果没有就放行到web资源中
		if(data==null){
			MyResponse myResponse=new MyResponse(response);

			chain.doFilter(request, response);
//			4、返回后将缓存数据放到缓存中，便于下次使用
			data=myResponse.getBuffer();
//			6、向浏览器输出
			cache.put(uri, data);

			System.out.println("从服务端获取资源");
		}else{
//			5、如果有，就直接从缓存中取得数据
			System.out.println("从缓存读取");
			chain.doFilter(request, response);

		}

	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {

	}

}

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ShowServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
			ServletOutputStream sout=response.getOutputStream();
			sout.write("fgfgdfsgdsfgdsfgdsfgdsfgsdfgdsdsfgdsfgsdfgdsfgsdfgkjslkdfjgl;kdsjglsdjfglsdjfgldfsjglksdfjgsfdl".getBytes());

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

	}

}