package com.example.demo.file;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.*;
import io.netty.handler.codec.http.*;
import io.netty.handler.stream.ChunkedFile;
import io.netty.util.CharsetUtil;
import javax.activation.MimetypesFileTypeMap;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.regex.Pattern;
/**
* 文件处理类
* @author
* @date 2019年11月20日
*/
public class HttpFileServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {
private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");
//文件名称匹配规则，必须是英文、数字下划线、中划线
private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");
//文件路徑
private final String url;
public HttpFileServerHandler(String url) {
this.url = url;
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
// 如果无法解码,返回400
if (!request.decoderResult().isSuccess()) {
sendError(ctx, HttpResponseStatus.BAD_REQUEST);
return;
}
//只支持GET方法,其他方法返回
if (request.method() != HttpMethod.GET) {
sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED);
return;
}
//获取文件路径
final String uri = request.uri();
// 格式化URL，并且获取文件的磁盘路径
final String path = sanitizeUri(uri);
if (path == null) {
sendError(ctx, HttpResponseStatus.FORBIDDEN);
return;
}
File file = new File(path);
// 如果文件隐藏不可访问或者文件不存在
if (file.isHidden() || !file.exists()) {
sendError(ctx, HttpResponseStatus.NOT_FOUND);
return;
}
//如果是文件目录
if (file.isDirectory()) {
//以/结尾时，就列出文件夹下的所有文件
if (uri.endsWith("/")) {
sendListing(ctx, file);
} else {
//否则进行重定向，打开文件夹，继续深入
sendRedirect(ctx, uri + '/');
}
return;
}
//既不是文件夹，也不是文件
if (!file.isFile()) {
sendError(ctx, HttpResponseStatus.FORBIDDEN);
return;
}
//读取文件，显示在html页面上
RandomAccessFile randomAccessFile = null;
try {
// 以只读的方式打开文件
randomAccessFile = new RandomAccessFile(file, "r");
} catch (FileNotFoundException fnfe) {
//出现错误，直接返回
sendError(ctx, HttpResponseStatus.NOT_FOUND);
return;
}
//获取文件长度
long fileLength = randomAccessFile.length();
//创建一个默认的HTTP响应
HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
//设置Content Length
HttpUtil.setContentLength(response, fileLength);
//设置Content Type
setContentTypeHeader(response, file);
//如果request中有KEEP ALIVE信息
if (HttpUtil.isKeepAlive(request)) {
//保持长连接
response.headers().set(HttpHeaderNames.CONNECTION, HttpHeaderValues.KEEP_ALIVE);
}
ctx.write(response);
//通过Netty的ChunkedFile对象直接将文件写入发送到缓冲区中
ChannelFuture sendFileFuture = ctx.write(new ChunkedFile(randomAccessFile, 0, fileLength, 8192), ctx.newProgressivePromise());
//文件监听
sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
@Override
public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) {
//不知道文件的大小
if (total < 0) {
System.err.println("文件访问进度: " + progress);
} else {
System.err.println("文件访问进度， " + progress + " / " + total + "，总长度：" + total + ",已读取：" + progress);
}
}
@Override
public void operationComplete(ChannelProgressiveFuture future) throws Exception {
System.out.println("文件展示完成。");
}
});
ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
//如果不支持keep-Alive，服务器端主动关闭请求
if (!HttpUtil.isKeepAlive(request)) {
lastContentFuture.addListener(ChannelFutureListener.CLOSE);
}
}
/**
* 异常处理
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
if (ctx.channel().isActive()) {
sendError(ctx, HttpResponseStatus.INTERNAL_SERVER_ERROR);
}
}
/**
* 格式化uri，返回文件的磁盘路径
* @param uri
* @return
*
*/
private String sanitizeUri(String uri) {
try {
uri = URLDecoder.decode(uri, "UTF-8");
} catch (UnsupportedEncodingException e) {
//用utf-8解码出现错误时，就换种解码方式
try {
uri = URLDecoder.decode(uri, "ISO-8859-1");
} catch (UnsupportedEncodingException e1) {
throw new Error();
}
}
if (!uri.startsWith(url)) {
return null;
}
if (!uri.startsWith("/")) {
return null;
}
uri = uri.replace('/', File.separatorChar);
if (uri.contains(File.separator + '.')
|| uri.contains('.' + File.separator) || uri.startsWith(".")
|| uri.endsWith(".") || INSECURE_URI.matcher(uri).matches()) {
return null;
}
System.out.println(System.getProperty("user.dir"));
//
return System.getProperty("user.dir") + File.separator + uri;
}
/**
* 展示文件列表
* @param ctx
* @param dir
*
*/
private static void sendListing(ChannelHandlerContext ctx, File dir) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html; charset=UTF-8");
StringBuilder buf = new StringBuilder();
String dirPath = dir.getPath();
buf.append("<!DOCTYPE html>\r\n");
buf.append("<html><head><title>");
buf.append("使用netty做下载文件服务器");
buf.append("</title></head><body>\r\n");
buf.append("<h3>");
buf.append("当前文件夹位置：");
buf.append(dirPath);
buf.append("</h3>\r\n");
buf.append("<h4>");
buf.append("文件列表");
buf.append("</h4>\r\n");
buf.append("<ul>");
buf.append("<li>上一级链接：<a href=\"../\">..</a></li>\r\n");
for (File f : dir.listFiles()) {
//隐藏文件，不可读文件直接跳过
if (f.isHidden() || !f.canRead()) {
continue;
}
String name = f.getName();
//非英文、数字、下划线、中划线组成的文件，也跳过
if (!ALLOWED_FILE_NAME.matcher(name).matches()) {
continue;
}
buf.append("<li>链接：<a href=\"");
buf.append(name);
buf.append("\">");
buf.append(name);
buf.append("</a></li>\r\n");
}
buf.append("</ul></body></html>\r\n");
ByteBuf buffer = Unpooled.copiedBuffer(buf, CharsetUtil.UTF_8);
response.content().writeBytes(buffer);
buffer.release();
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
/**
* 发送重定向
* @param ctx
* @param newUri
*
*/
private static void sendRedirect(ChannelHandlerContext ctx, String newUri) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.FOUND);
//设置访问的url路径为新的文件夹路径
response.headers().set(HttpHeaderNames.LOCATION, newUri);
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
/**
* 显示错误信息
* @param ctx
* @param status
*
*/
private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, status, Unpooled.copiedBuffer("Failure: " + status.toString() + "\r\n", CharsetUtil.UTF_8));
response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain; charset=UTF-8");
ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
}
/**
* 设置文件头部
* @param response
* @param file
*
*/
private static void setContentTypeHeader(HttpResponse response, File file) {
MimetypesFileTypeMap mimeTypesMap = new MimetypesFileTypeMap();
response.headers().set(HttpHeaderNames.CONTENT_TYPE, mimeTypesMap.getContentType(file.getPath()));
}
}
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