tomcat设置gzip压缩的原理及配置方法

<Connector port="80" protocol="HTTP/1.1"  
      connectionTimeout="20000"  
      redirectPort="8443" executor="tomcatThreadPool" URIEncoding="utf-8"  
            compression="on"  
            compressionMinSize="50" noCompressionUserAgents="gozilla, traviata"  
            compressableMimeType="text/html,text/xml,text/javascript,text/css,text/plain" /> 

compression="on" 打开压缩功能 
"50" 启用压缩的输出内容大小，默认为2KB 
"gozilla, traviata" 对于以下的浏览器，不启用压缩 
"text/html,text/xml,text/javascript,text/css,text/plain"　哪些资源类型需要压缩

@Test 
public void testGzip() { 
    HttpClient httpClient = new HttpClient(); 
    GetMethod getMethod = new GetMethod("http://localhost/admin.jsp"); 
    try { 
        getMethod.addRequestHeader("accept-encoding", "gzip,deflate"); 
        getMethod.addRequestHeader("user-agent","Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; Alexa Toolbar; Maxthon 2.0)"); 
        int result = httpClient.executeMethod(getMethod); 
        if (result == 200) { 
            System.out.println(getMethod.getResponseContentLength()); 
            String html = getMethod.getResponseBodyAsString(); 
            System.out.println(html); 
            System.out.println(html.getBytes().length); 
        } 
    } catch (HttpException e) { 
        e.printStackTrace(); 
    } catch (IOException e) { 
        e.printStackTrace(); 
    } finally { 
        getMethod.releaseConnection(); 
    } 
}