读取js压缩为gzjs格式文件

    最近做的Ext项目Ext的插件都比较大,对于网页的浏览速度也是非常不容乐观的，于是就需要对所加载的js文件进行优化，其中一个方法就是对于较大的js文件可以进行压缩。压缩成gzjs格式，但是gzjs后缀名的文件又不能被浏览器所认识，得需要对服务器端做些处理。

一、将js格式文件压缩成gzjs格式。使用gzip.exe打包压缩后的JS文件，最后生成xx.js.gz，把xx.js.gz文件改成xx.gzjs。压缩实例： ext-all.js （610KB）, gzip.exe压缩后为ext-all.gzjs（168KB）。
附：gzip使用方法，在命令行下输入： gzip -9 ext-all.js ext-all.js.gz
修改ext-all.js.gz的后缀名ext-all.gzjs（注：也可以通过gzip -h命令查看帮助）
下载地址：http://www.gzip.org

二、在项目web.xml中加入过滤器。
代码如下：

<filter>
      <filter-name>GzipJsFilter</filter-name>
      <filter-class>net.kangsoft.util.GzipJsFilter</filter-class>
      <init-param>
          <param-name>headers</param-name>
          <param-value>Content-Encoding=gzip</param-value>
      </init-param>
</filter>
   <filter-mapping>
   <filter-name>GzipJsFilter</filter-name>
   <url-pattern>*.gzjs</url-pattern>
</filter-mapping>

<filter> 
      <filter-name>GzipJsFilter</filter-name> 
      <filter-class>net.kangsoft.util.GzipJsFilter</filter-class> 
      <init-param> 
          <param-name>headers</param-name> 
          <param-value>Content-Encoding=gzip</param-value> 
      </init-param>
</filter>
   <filter-mapping>
   <filter-name>GzipJsFilter</filter-name>
   <url-pattern>*.gzjs</url-pattern>
</filter-mapping>

三、加入过滤类。

代码如下：

package net.kangsoft.util;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
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;

public class GzipJsFilter
implements Filter
{
Map headers = new HashMap();

public void destroy() { }

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)

throws IOException, ServletException {
    if (req instanceof HttpServletRequest)
      doFilter((HttpServletRequest)req, (HttpServletResponse)res, chain);
    else
      chain.doFilter(req, res);
}

public void doFilter(HttpServletRequest request, HttpServletResponse response,

FilterChain chain)
    throws IOException, ServletException
{
    request.setCharacterEncoding("UTF-8");
    for (Iterator it = this.headers.entrySet().iterator(); it.hasNext(); ) {
      Map.Entry entry = (Map.Entry)it.next();
      response.addHeader((String)entry.getKey(), (String)entry.getValue());
    }
    chain.doFilter(request, response);
}

public void init(FilterConfig config) throws ServletException {
    String headersStr = config.getInitParameter("headers");
    String[] headers = headersStr.split(",");
    for (int i = 0; i < headers.length; ++i) {
      String[] temp = headers[i].split("=");
      this.headers.put(temp[0].trim(), temp[1].trim());
    }
}
}

package net.kangsoft.util;

import java.io.IOException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
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;

public class GzipJsFilter
implements Filter
{
Map headers = new HashMap();

public void destroy() { }

public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)

throws IOException, ServletException {
    if (req instanceof HttpServletRequest)
      doFilter((HttpServletRequest)req, (HttpServletResponse)res, chain);
    else
      chain.doFilter(req, res);
}

public void doFilter(HttpServletRequest request, HttpServletResponse response,

FilterChain chain)
    throws IOException, ServletException
{
    request.setCharacterEncoding("UTF-8");
    for (Iterator it = this.headers.entrySet().iterator(); it.hasNext(); ) {
      Map.Entry entry = (Map.Entry)it.next();
      response.addHeader((String)entry.getKey(), (String)entry.getValue());
    }
    chain.doFilter(request, response);
}

public void init(FilterConfig config) throws ServletException {
    String headersStr = config.getInitParameter("headers");
    String[] headers = headersStr.split(",");
    for (int i = 0; i < headers.length; ++i) {
      String[] temp = headers[i].split("=");
      this.headers.put(temp[0].trim(), temp[1].trim());
    }
}
}

四、在需导入js的页面head里面添加导入文件，如：<script type="text/javascript"

src="js/ext3/ext-all.gzjs"></script>

至此已经大功告成，在我这边测试通过，如大家在运行过程中有问题,请发信息给我。