Web压缩过滤器

Web压缩过滤器

package mytest.gzipfilter;

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;

/**
* Servlet Filter implementation class GzipFilter
*/
public class GzipFilter implements Filter {

/**
* Default constructor.
*/
public GzipFilter() {
// TODO Auto-generated constructor stub
}

/**
* @see Filter#destroy()
*/
public void destroy() {
// TODO Auto-generated method stub
}

/**
* @see Filter#doFilter(ServletRequest, ServletResponse, FilterChain)
*/
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
// TODO Auto-generated method stub
// place your code here
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;

BufferHttpResponse bufferHttpResponse = new BufferHttpResponse(response);
// pass the request along the filter chain
chain.doFilter(request, bufferHttpResponse);
byte out[] = bufferHttpResponse.getBuffer();
ByteArrayOutputStream bout = new ByteArrayOutputStream();
GZIPOutputStream gout = new GZIPOutputStream(bout);
gout.write(out);
gout.close();

byte gzip[] = bout.toByteArray();
response.setHeader("content-encoding", "gzip");
response.setContentLength(gzip.length);
response.getOutputStream().write(gzip);
}

/**
* @see Filter#init(FilterConfig)
*/
public void init(FilterConfig fConfig) throws ServletException {
// TODO Auto-generated method stub
}

}

class BufferHttpResponse extends HttpServletResponseWrapper {
private HttpServletResponse response;
private ByteArrayOutputStream bout = new ByteArrayOutputStream();
private PrintWriter pw;

public BufferHttpResponse(HttpServletResponse response) {
super(response);
this.response = response;
}

@Override
public ServletOutputStream getOutputStream() throws IOException {
return new MyServletOutputStream(bout);
}

@Override
public PrintWriter getWriter() throws IOException {
pw = new PrintWriter(new OutputStreamWriter(bout,this.response.getCharacterEncoding()));
return pw;
}

public byte[] getBuffer() {
try {
if(pw != null){
pw.close();
}
if (bout != null)
bout.flush();
return bout.toByteArray();
} catch (Exception e) {
throw new RuntimeException(e);
}
}

}

class MyServletOutputStream extends ServletOutputStream {
private ByteArrayOutputStream bout;

public MyServletOutputStream(ByteArrayOutputStream bout) {
this.bout = bout;
}

@Override
public void write(int arg0) throws IOException {

}

}

web.xml中配置压缩内容

<filter>
<display-name>GzipFilter</display-name>
<filter-name>GzipFilter</filter-name>
<filter-class>mytest.gzipfilter.GzipFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>GzipFilter</filter-name>
<url-pattern>/*.jsp</url-pattern>
<dispatcher>FORWARD</dispatcher>
<dispatcher>REQUEST</dispatcher>
</filter-mapping>
<filter-mapping>
<filter-name>GzipFilter</filter-name>
<url-pattern>/*.css</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>GzipFilter</filter-name>
<url-pattern>/*.js</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>GzipFilter</filter-name>
<url-pattern>/*.html</url-pattern>
</filter-mapping>

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