response读取图片+下载图片

读取图片

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class OutServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

                  String url = this.getContext().getRealPath("test.jpg");
                  InputStream in = new FileInputStream(url);
                  OutputStream out = response.getOutputStream();
		  byte [] by = new by[1024];
                  int i = 0;
                  while((i=in.read(by))!=-1)
                 {

                         out.write(by,0,i);

                  }
                   in.close();

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request,response);
	}

}

　下载图片

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class OutServlet extends HttpServlet {

	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

//写入请求头下载图片文件

 responst.setHeader("Content-Disposition","attachment;filename=test.jpg");

	}

	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		doGet(request,response);
	}

}

可以使用

URLEncoder.encode("String","utf-8");   把一个String转成UTF-8

URLDecoder.decode("String","utf-8");   把一个String 解析成UTF-8

可以使用上面方法来给图片文件设置名称，

response.setHeader("Content-Dispostion","attachment;filename="+URLEncoder.encoder("测试.jpg","utf-8"));

常用的几种response输出数据格式(不乱码)

　　　①

　　　　　　response.setContentType("text/html;charset=utf-8");    // 告诉用UTF-8解析

　　　　　　response.setCharacterEncoding("utf-8");    // 告诉服务器用UTF-8 解析

　　　　　　response.getWriter().write("中国");

　　　②

　　　　　　response.setContenType("text/html;charset=utf-8");  // 告诉用UTF-8解析

　　　　　　response.getOutputStream().write("中国".getBytes("UTF-8"));  // 浏览器用UTF-8解析

　　　③

　　　　　  response.getOutputStream().write("中国".getBytes());     //按照浏览器默认的编码解析

　　　　　　　　　　日期:2018/05/21

原文地址：https://www.cnblogs.com/c-c-c-c/p/9069424.html