在web开发中，当服务器端向客户端返回的数据量比较大时，我们可以通过Gzip对数据进行压缩处理
注意：如果小数据量进行压缩，压缩后的数据可能比原始数据还大；所以response返回数据量比较小时不推荐使用
这里代码结构，红叉不需要关注，这里maven环境的问题，不影响我们的主线
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"> <display-name>gzipfilter</display-name> <filter> <filter-name>gzip</filter-name> <filter-class>gzipfilter.GzipFilter</filter-class> </filter> <filter-mapping> <filter-name>gzip</filter-name> <url-pattern>/servlet/*</url-pattern> </filter-mapping> <servlet> <servlet-name>TestServlet</servlet-name> <servlet-class>gzipfilter.TestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>TestServlet</servlet-name> <url-pattern>/servlet/test</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>
pom.xml
<dependencies>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
<type>jar</type>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.1</version>
<scope>provided</scope>
</dependency>
</dependencies>
GzipFilter
public class GzipFilter implements Filter{ public void init(FilterConfig config) throws ServletException { } public void destroy() { } public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; HttpServletResponse response = (HttpServletResponse) res; ResponseWrapper responseWrapper = new ResponseWrapper(response); chain.doFilter(request, responseWrapper);//通过过滤器 把响应数据写进自己的response中 //获得响应数据 ByteArrayOutputStream buffer=responseWrapper.getBuffer(); byte[] bytes=buffer.toByteArray(); //压缩 ByteArrayOutputStream baout=new ByteArrayOutputStream(); GZIPOutputStream gout=new GZIPOutputStream(baout); gout.write(bytes); gout.close();//拿到压缩后的数据----响应前端 byte[] gzipbytes = baout.toByteArray(); response.setHeader("Content-Encoding", "gzip"); System.out.println(gzipbytes.length+"-------------压缩后"); response.getOutputStream().write(gzipbytes); } } /** * * 对原始response进行包装 * */ class ResponseWrapper extends HttpServletResponseWrapper { private ByteArrayOutputStream buffer = new ByteArrayOutputStream(); private PrintWriter pw; public ResponseWrapper(HttpServletResponse response) { super(response); } @Override public ServletOutputStream getOutputStream() throws IOException { OutputStreamWrapper out = new OutputStreamWrapper(buffer); return out; } @Override public PrintWriter getWriter() throws IOException { if(pw==null){ OutputStreamWrapper out = new OutputStreamWrapper(buffer); pw = new PrintWriter(new OutputStreamWriter(out, "UTF-8")); } return pw; } public ByteArrayOutputStream getBuffer(){ return buffer; } } /** * * 包装 outputStream * */ class OutputStreamWrapper extends ServletOutputStream{ private ByteArrayOutputStream buffer; public OutputStreamWrapper(ByteArrayOutputStream buffer) { super(); this.buffer=buffer; } @Override public void write(int b) throws IOException { this.buffer.write(b); } }
TestServlet
public class TestServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String name="a"; for(int i=0;i<10;i++){ name=name+name; } System.out.println(name.getBytes().length+"==============压缩前"); response.getOutputStream().write(name.getBytes()); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP ‘index.jsp‘ starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> </head> <body> <a href="servlet/test">点点</a> </body> </html>
结果：
