servlet--全局のデータを統一的に圧縮

Filter実装、ここでは親を書くHttpServeretResponseのresponseから

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.zip.GZIPOutputStream;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

public class GzipFilter implements Filter {

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

	}

	@Override
	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		
		// 0   
		HttpServletRequest request = (HttpServletRequest) req;
		HttpServletResponse response = (HttpServletResponse) resp;
		
		//       ，     response，      ，             ，         ， tomcat  ，     
		
		//1       --      
		final ByteArrayOutputStream customBuffer = new ByteArrayOutputStream();
		
		
		//2   response
		HttpServletResponse myResponse = new HttpServletResponseWrapper(response){
			//          
			
			//  getOutputStream
			@Override
			public ServletOutputStream getOutputStream() throws IOException {
				return new ServletOutputStream(){

					@Override
					public void write(int b) throws IOException {
						//              
						customBuffer.write(b);
					}
					
				};
			}
			
			private PrintWriter pw;
			@Override
			public PrintWriter getWriter() throws IOException {
				pw = new PrintWriter(new OutputStreamWriter(getOutputStream(),getCharacterEncoding()));
				return pw;
			}
			
			@Override
			public void flushBuffer() throws IOException {
				if(pw != null){
					pw.flush();
				}
			}
			
			
		};
		
		
		
		//3.  
		chain.doFilter(request, myResponse);  //          
		
		
		//4    
		byte[] servletData = customBuffer.toByteArray();
		
		//5  
		// *         
		ByteArrayOutputStream gzipBAOS = new ByteArrayOutputStream();
		GZIPOutputStream gzipOut = new GZIPOutputStream(gzipBAOS);
		// *     
		gzipOut.write(servletData);
		gzipOut.close();
		
		// *          
		byte[] gzipData = gzipBAOS.toByteArray();
		
		//6    
		// *    ，Accept-Encoding: gzip，            
		// *                
		response.setHeader("content-encoding", "gzip");
		response.getOutputStream().write(gzipData);
		

	}

	@Override
	public void destroy() {

	}

}

servletテストコード:

import java.io.IOException;

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

public class GzipGetDataServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		this.doPost(request, response);
	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.setContentType("text/html;charset=UTF-8");
		
		// 90w        
		
		StringBuilder builder = new StringBuilder();
		for(int i =0 ; i < 1000 ; i ++){
			builder.append("    <br/>");
		}
			
		//response.getOutputStream().print(builder.toString());
		response.getWriter().print(builder.toString());
	}

}