Response-响应头、自定义重定向、文字\IO输出、文件下载

设置响应头

package com.itheima.header;import java.io.IOException;import java.util.Date;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class HeaderServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //设置响应头        response.addHeader("name", "zhangsan");        response.addHeader("name", "lisi");        response.setHeader("age", "28");        response.setHeader("age", "50");    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

浏览器输入：
http://localhost:8080/WEB14/header

设置响应头，重定向请求

package com.itheima.header;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class Servlet1 extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //没有响应 告知客户端去重定向到servlet2        //1、设置状态码302        //response.setStatus(302);        //2、设置响应头Location        //response.setHeader("Location", "/WEB14/servlet2");        //封装成一个重定向的方法sendRedirect(url)        //response.sendRedirect("servlet2");也可以的        response.sendRedirect("/WEB14/servlet2");    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

设置响应头，5秒跳转

package com.itheima.header;import java.io.IOException;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class RefreshServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //设置定时刷新的头        response.setHeader("refresh", "5;url=http://www.baidu.com");    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

Response文字输出

package com.itheima.content;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class TextServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //设置response查询的码表        //response.setCharacterEncoding("UTF-8");        //通过一个头 Content-Type 告知客户端使用何种码表        //response.setHeader("Content-Type", "text/html;charset=UTF-8");        //以下一行代码即可解决        response.setContentType("text/html;charset=UTF-8");        PrintWriter writer = response.getWriter();        //writer.write("hello response!!!");        writer.write("你好");    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

Response IO输出

package com.itheima.content;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class ByteServlet extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //使用response获得字节输出流        ServletOutputStream out = response.getOutputStream();        //获得服务器上的图片        String realPath = this.getServletContext().getRealPath("a.jpg");        InputStream in = new FileInputStream(realPath);        int len = 0;        byte[] buffer = new byte[1024];        while((len=in.read(buffer))>0){            out.write(buffer, 0, len);        }        in.close();        out.close();    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}

图片a.jpg的位置如下：

Response 文件下载

    <a href="/WEB14/downloadServlet?filename=a.flv">a.flv</a><br>    <a href="/WEB14/downloadServlet?filename=a.jpg">a.jpg</a><br>    <a href="/WEB14/downloadServlet?filename=a.mp3">a.mp3</a><br>    <a href="/WEB14/downloadServlet?filename=a.mp4">a.mp4</a><br>    <a href="/WEB14/downloadServlet?filename=a.txt">a.txt</a><br>    <a href="/WEB14/downloadServlet?filename=a.zip">a.zip</a><br>    <a href="/WEB14/downLoadServlet2?filename=美女.jpg">美女.jpg</a><br>

package com.itheima.content;import java.io.FileInputStream;import java.io.IOException;import java.io.InputStream;import java.net.URLEncoder;import javax.servlet.ServletException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import sun.misc.BASE64Encoder;public class DownLoadServlet2 extends HttpServlet {    protected void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        //*******文件名称是中文的下载*******        //获得要下载的文件的名称        String filename = request.getParameter("filename");//????.jpg        //解决获得中文参数的乱码----下节课讲        filename = new String(filename.getBytes("ISO8859-1"),"UTF-8");//美女.jpg        //获得请求头中的User-Agent        String agent = request.getHeader("User-Agent");        //根据不同浏览器进行不同的编码        String filenameEncoder = "";        if (agent.contains("MSIE")) {            // IE浏览器            filenameEncoder = URLEncoder.encode(filename, "utf-8");            filenameEncoder = filenameEncoder.replace("+", " ");        } else if (agent.contains("Firefox")) {            // 火狐浏览器            BASE64Encoder base64Encoder = new BASE64Encoder();            filenameEncoder = "=?utf-8?B?"                    + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";        } else {            // 其它浏览器            filenameEncoder = URLEncoder.encode(filename, "utf-8");                     }        //要下载的这个文件的类型-----客户端通过文件的MIME类型去区分类型        response.setContentType(this.getServletContext().getMimeType(filename));        //告诉客户端该文件不是直接解析 而是以附件形式打开(下载)----filename="+filename 客户端默认对名字进行解码        response.setHeader("Content-Disposition", "attachment;filename="+filenameEncoder);        //获取文件的绝对路径        String path = this.getServletContext().getRealPath("download/"+filename);        //获得该文件的输入流        InputStream in = new FileInputStream(path);        //获得输出流---通过response获得的输出流 用于向客户端写内容        ServletOutputStream out = response.getOutputStream();        //文件拷贝的模板代码        int len = 0;        byte[] buffer = new byte[1024];        while((len=in.read(buffer))>0){            out.write(buffer, 0, len);        }        in.close();        //out.close();    }    protected void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}