spring集成GZIP

文章来自：http://www.javablog.fr/javaweb-gzip-compression-protocol-http-filter-gzipresponsewrapper-gzipresponsewrapper.html#comment-11588

第一步：实现GZIP压缩流

package com.utils;

import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;

public class GZIPResponseWrapper extends HttpServletResponseWrapper {

  protected HttpServletResponse origResponse = null;
  protected ServletOutputStream stream = null;
  protected PrintWriter writer = null;
 
  public GZIPResponseWrapper(HttpServletResponse response) {
    super(response);
    origResponse = response;
  }


  public ServletOutputStream createOutputStream() throws IOException {
    return (new GZIPResponseStream(origResponse));
  }

  public void finishResponse() {
    try {
      if (writer != null) {
        writer.close();
      } else {
        if (stream != null) {
          stream.close();
        }
      }
    } catch (IOException e) {
   
    }
  }

  public void flushBuffer() throws IOException {
    stream.flush();
  }


  public ServletOutputStream getOutputStream() throws IOException {
    if (writer != null) {
      throw new IllegalStateException("getWriter() has already been called!");
    }
    if (stream == null)
      stream = createOutputStream();
    return (stream);
  }

  public PrintWriter getWriter() throws IOException {
    if (writer != null) {
      return (writer);
    }
    if (stream != null) {
      throw new IllegalStateException("getOutputStream() has already been called!");
    }
   stream = createOutputStream();
   writer = new PrintWriter(new OutputStreamWriter(stream, "UTF-8"));
   return (writer);
  }
  public void setContentLength(int length) {}
}

package com.utils;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

public class GZIPResponseStream extends ServletOutputStream {

  protected ByteArrayOutputStream baos = null;
  protected GZIPOutputStream gzipstream = null;
  protected boolean closed = false;
  protected HttpServletResponse response = null;
  protected ServletOutputStream output = null;


  public GZIPResponseStream(HttpServletResponse response) throws IOException {
    super();
    closed = false;
    this.response = response;
    this.output = response.getOutputStream();
    baos = new ByteArrayOutputStream();
    gzipstream = new GZIPOutputStream(baos);
  }

  public void close() throws IOException {
    if (closed) {
      throw new IOException("This output stream has already been closed");
    }
    gzipstream.finish();
    byte[] bytes = baos.toByteArray();
    response.addHeader("Content-Length",Integer.toString(bytes.length));
    response.addHeader("Content-Encoding", "gzip");
    output.write(bytes);
    output.flush();
    output.close();
    closed = true;
  }

  public void flush() throws IOException {
    if (closed) {
      throw new IOException("Cannot flush a closed output stream");
    }
    gzipstream.flush();
  }

  public void write(int b) throws IOException {
    if (closed) {
      throw new IOException("Cannot write to a closed output stream");
    }
    gzipstream.write((byte)b);
  }

  public void write(byte b[]) throws IOException {
    write(b, 0, b.length);
  }


  public void write(byte b[], int off, int len) throws IOException {
    if (closed) {
      throw new IOException("Cannot write to a closed output stream");
    }
    gzipstream.write(b, off, len);
  }

  public boolean closed() {
    return (this.closed);
  }
  public void reset() {
    //noop
  }

}

第二步：实现一个GZIPFilter过滤器

package com.ssh.filter;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.utils.GZIPResponseWrapper;


/**
 *
 */
public class GZIPFilter implements Filter{

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

}

@Override
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
if (req instanceof HttpServletRequest) {
            HttpServletRequest request = (HttpServletRequest) req;
            HttpServletResponse response = (HttpServletResponse) res;
            String ae = request.getHeader("accept-encoding");
            if (ae != null && ae.indexOf("gzip") != -1) {

//如果是gzip，则使用GZIP方式作为输出流
                GZIPResponseWrapper wrappedResponse = new GZIPResponseWrapper(response);
                chain.doFilter(req, wrappedResponse);
                wrappedResponse.finishResponse();
                return;
            }
            chain.doFilter(req, res);
        }
}

@Override
public void destroy() {
// TODO Auto-generated method stub

}
}

第三步：将GZIPFilter纳入spring管理

application-bean配置：

<bean id="GZIPFilter" class="com.ssh.filter.GZIPFilter"></bean>

web.xml配置：

<filter>
  <filter-name>GZIPFilter</filter-name>

<!--必须使用spring提供的这个代理filter，自定义filter不会被纳入spring 容器-->
  <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
  </filter>
  <filter-mapping>
  <filter-name>GZIPFilter</filter-name>
  <url-pattern>/*</url-pattern>
  </filter-mapping>