设置字节响应类型

常见的字节型响应：
resp.setContentType(“image/jpeg”)
设置响应类型为图片类型，图片类型为jpeg或jpg格式。
resp.setContentType(“image/gif”)
设置响应类型为图片类型，图片类型为gif格式。

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.*;
public class ResponseByteServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        this.doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        //读取响应的图片
        File file = new File("D:\\DownloadFile/rog.jpg");
        //创建读取图片的io流对象
        InputStream inputStream = new FileInputStream(file);
        //图片缓冲区
        byte[] buff = new byte[inputStream.available()];
        inputStream.read(buff);
        //产生字节型响应
        resp.setContentType("image/jpg");
        //获取字节输出流
        OutputStream outputStream = resp.getOutputStream();
        outputStream.write(buff);
        outputStream.flush();
        outputStream.close();
        inputStream.close();
    }
}