javaweb--Filter全站压缩

1.Filter代码：

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.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

//全站压缩
public class GzipFilter implements Filter {

	public void destroy() {

	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		
		HttpServletRequest request = (HttpServletRequest)req;
		HttpServletResponse response = (HttpServletResponse)resp;
		
		GzipHttpServletResponse gresponse = new GzipHttpServletResponse(response);
		chain.doFilter(request, gresponse);
		//找一个缓冲字节流
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		//将数据压缩到字节流中
		byte [] b = gresponse.getOldBytes();
		GZIPOutputStream gouts = new GZIPOutputStream(baos);
		System.out.println("压缩前的数据大小： "+b.length);
		gouts.write(b);
		gouts.close();
		//从缓冲字节流中获取数据
		b = baos.toByteArray();
		System.out.println("压缩后的数据大小："+b.length);
		//一定要指定压缩方式
		response.setHeader("Content-Encoding", "gzip");
		//通知客户端大小
		response.setContentLength(b.length);
		ServletOutputStream out = response.getOutputStream();
		out.write(b);
		

	}

	public void init(FilterConfig arg0) throws ServletException {

	}

}

class GzipHttpServletResponse extends HttpServletResponseWrapper
{
	private ByteArrayOutputStream baos = new ByteArrayOutputStream();
    private PrintWriter pw;
	public GzipHttpServletResponse(HttpServletResponse response) {
		super(response);
	}

	//字节流处理
	@Override
	public ServletOutputStream getOutputStream() throws IOException {
		
		return new MyServletOutputStream(baos);
	}
	//字符流处理
	@Override
	public PrintWriter getWriter() throws IOException {
	
		//解决编码问题OutputStreamWriter
		pw = new PrintWriter(new OutputStreamWriter(baos, super.getCharacterEncoding()));
		return pw;
	}
	
	//返回baos中的数据
	public byte[] getOldBytes()
	{
		try {
			if(pw != null)
			{
				pw.close();
			}
			baos.flush();
		} catch (IOException e) {
			e.printStackTrace();
		}
		
		return baos.toByteArray();
	}

	
}
class MyServletOutputStream extends ServletOutputStream
{
	ByteArrayOutputStream baos;
	public MyServletOutputStream(ByteArrayOutputStream baos)
	{
		this.baos = baos;
		
	}
	@Override
	public void write(int b) throws IOException {
		baos.write(b);
	}
   	

}

web.xml中配置

	<!-- 压缩过滤器 -->
	<filter>
		<filter-name>GzipFilter</filter-name>
		<filter-class>com.hhtc.filter.GzipFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>GzipFilter</filter-name>
		<url-pattern>/*</url-pattern>
	</filter-mapping>