從HttpServletRequest中讀取檔案內容
阿新 • • 發佈：2019-01-29
這裡介紹如何利用表單來將檔案傳輸到伺服器。
首先我們的前臺jsp頁面的原始碼如下
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content web.xml中的配置如下
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://java.sun.com/xml/ns/javaee" id="WebApp_ID" version="2.5">
<!--配置servlet -->
<servlet> 接下來就是我們後臺的程式碼了
在這裡我將從HttpServletRequest中讀取檔案的方法封裝成一個靜態的方法，放在FilEUploadUtils.getFileContentFromRequest()。
則控制器的程式碼如下
package com.blog.upload;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class FileUploadController extends HttpServlet {
private static final long serialVersionUID = 1L;
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
String content=FilEUploadUtils.getFileContentFromRequest(request); //獲取檔案的內容
System.out.println(content); //輸出檔案的內容
}
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
super.doGet(req, resp);
}
}靜態方法getFileContentFromRequest中的程式碼如下
package com.blog.upload;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import javax.servlet.http.HttpServletRequest;
import org.apache.tomcat.util.http.fileupload.FileItemIterator;
import org.apache.tomcat.util.http.fileupload.FileItemStream;
import org.apache.tomcat.util.http.fileupload.disk.DiskFileItemFactory;
import org.apache.tomcat.util.http.fileupload.servlet.ServletFileUpload;
public class FilEUploadUtils {
public static String getFileContentFromRequest(HttpServletRequest request){
try{
request.setCharacterEncoding("utf-8");
if(ServletFileUpload.isMultipartContent(request)) {
DiskFileItemFactory diskFileItemFactory=new DiskFileItemFactory();// 建立該物件
ServletFileUpload fileUpload=new ServletFileUpload(diskFileItemFactory);// 建立該物件
FileItemIterator itemIterator=fileUpload.getItemIterator(request);// 解析request 請求,並返回FileItemIterator集合
StringBuffer fileContent=new StringBuffer();
while(itemIterator.hasNext()) {
FileItemStream itemStream=itemIterator.next();//從集合中獲得一個檔案流
if(!itemStream.isFormField() && itemStream.getName().length() > 0) { //過濾掉表單中非檔案
BufferedInputStream inputStream=new BufferedInputStream(itemStream.openStream()); //獲得檔案輸入流
inputStream.mark(itemStream.openStream().available()+1);
//判斷上傳的檔案的編碼格式 支援 UTF-8 和 ANSI兩種型別
String charsetName=getFileCharsetName(inputStream);
BufferedReader bufferedReader=new BufferedReader(new InputStreamReader(inputStream,charsetName));
String lineTxt=null;
while((lineTxt=bufferedReader.readLine()) != null) {
fileContent.append(lineTxt+"\r");
}
}
}
return fileContent.toString();
}
} catch(Exception e) {
e.printStackTrace();
}
return null;
}
//判斷上傳的檔案的編碼格式 支援 UTF-8 和 ANSI兩種型別
private static String getFileCharsetName(InputStream inputStream) throws IOException{
String charsetName="GBK";
byte[] typeByte = new byte[3];
inputStream.read(typeByte);
if (typeByte[0] == -17 && typeByte[1] == -69 && typeByte[2] == -65){
charsetName="UTF-8";
}
else{
charsetName="GBK";
}
inputStream.reset();
return charsetName;
}
}