图片从后台响应给浏览器

package com.atping.servlet_;



import org.apache.commons.io.IOUtils;

import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.FileInputStream;
import java.io.IOException;
@WebServlet("/demo02")
public class HelloServlet02 extends HttpServlet {
    private Object buff;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //相对路径下获取图片位置 图片资源放在web目录下
        // String path = req.getServletContext().getRealPath("img/123.jpg");
        //FileInputStream inputStream = new FileInputStream(path);
        FileInputStream inputStream = new FileInputStream("D:\\代码\\February\\java0209\\web\\img\\123.jpg");
        ServletOutputStream outputStream = resp.getOutputStream();
//        byte[] buff = new byte[1024];
//        int total = inputStream.read(buff);
//        while (total != -1){
//            outputStream.write(buff,0,total);
//            total = inputStream.read(buff);
//        }
//        //关流，创建出来的对象需要关闭流，方法点出来的流不需要关闭，服务器关闭 方法点出来流自动关闭，不需要手动关闭
//        inputStream.close();
        //第二种方法
//        int len = 0;
//        while ((len = inputStream.read(buff)) != -1){
//            outputStream.write(buff,0,len);
//        }
//        inputStream.close();
        //第三种 调用工具类方法  IOUtils
        IOUtils.copy(inputStream,outputStream);
        inputStream.close();
    }
}