通过response向服务器用Io流写入图片

 

 1.响应头设置字节。

    使用response获得字节输出流  
     ServletOutputStream out = response.getOutputStream();

    获取文件的绝对路径
        String realPath = this.getServletContext().getRealPath("a.jpg");

    获得服务器上的图片
        FileInputStream in=new FileInputStream(realPath);

package com.hdh.content;

import java.io.FileInputStream;
import java.io.IOException;

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 {
        // 用response获得字节输出流
        ServletOutputStream sos = response.getOutputStream();
        // 获取文件的绝对路径
        String realPath = this.getServletContext().getRealPath("a.jpg");
        // 获得服务器上的图片
        FileInputStream fis = new FileInputStream(realPath);

        int len = 0;
        byte[] buffer = new byte[1024];
        while ((len = fis.read(buffer)) > 0) {
            sos.write(buffer, 0, len);

        }
        fis.close();
        sos.close();
    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        doGet(request, response);
    }

}