版权声明：yanghaha的原创博客 https://blog.csdn.net/qq_44758435/article/details/90636619

文件下载

需要先导入两个jar包

commons-fileupload-1.3.1.jar

commons-io-2.4.jar

String fileName = request.getParameter("fileName");

//下载文件，需要设置两个响应头

//application/octet-stream任意文件类型

response.addHeader("content-Type", "application/octet-stream");

//对于不同浏览器进行处理

//根据请求头user-agent

//attachment打开对话框下载 inline直接打开

String agent = request.getHeader("User-agent");

if(agent.indexOf("Firefox")!=-1) {

response.addHeader("content-Disposition", "attachment;fileName==?UTF-8?B?"+Base64.getEncoder().encodeToString(fileName.getBytes("utf-8"))+"?=");

}else if(agent.indexOf("Edge")!=-1) {

response.addHeader("content-Disposition", "attachment;fileName="+URLEncoder.encode(fileName, "utf-8"));

}

//servlet 通过文件路径将文件转换为输入流 读到servlet中

InputStream in = getServletContext().getResourceAsStream("/res/"+fileName);

//输出流

ServletOutputStream out = response.getOutputStream();

byte[] bt = new byte[10];

int len = -1;

//将缓冲区的读取bt

while((len=in.read(bt))!=-1) {

//将bt里的输出到response

out.write(bt,0,len);

}

out.close();

in.close();

文件下载名中文乱码问题

(1).edge

response.addHeader("content-Disposition", "attachment;fileName="+URLEncoder.encode(fileName, "utf-8"));

(2).火狐

response.addHeader("content-Disposition", "attachment;fileName==?UTF-8?B?"+Base64.getEncoder().encodeToString(fileName.getBytes("utf-8"))+"?=");

(3).综合处理

String agent = request.getHeader("User-agent");

if(agent.indexOf("Firefox")!=-1) {

response.addHeader("content-Disposition", "attachment;fileName==?UTF-8?B?"+new String(Base64.encodeBase64(fileName.getBytes("utf-8")))+"?=");

}else if(agent.indexOf("Edge")!=-1) {

response.addHeader("content-Disposition", "attachment;fileName="+URLEncoder.encode(fileName, "utf-8"));

}