使用Servlet和Bootstrap上传Ajax文件

介绍

在本教程中，我们将检查Ajax文件上传如何与Servlet一起使用。同样，我们将用Bootstrap装饰表单并通过jQuery Ajax上传ajaxify文件。

实作

基本的servlet实现是相同的。因此，我们需要做的第一件事是更新我们的web.xml文件并为我们的应用程序指定servlet。

web.xml

<?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" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0"><display-name>DemoFileUploadServlet</display-name><welcome-file-list><welcome-file>home.jsp</welcome-file></welcome-file-list><servlet><description></description><display-name>DemoFileUploadServlet</display-name><servlet-name>demo</servlet-name><servlet-class>com.jcombat.sample.DemoFileUploadServlet</servlet-class></servlet><servlet-mapping><servlet-name>demo</servlet-name><url-pattern>/demo</url-pattern></servlet-mapping>
</web-app>

请注意，指定的欢迎页面为home.jsp 。因此，当我们运行servlet应用程序时，该应用程序应该找到欢迎页面jsp和servlet类，即DemoFileUploadServlet 。

home.jsp

<%@page contentType="text/html" 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="text/html; charset=UTF-8">
<title>File Upload Example in JSP and Servlet - Java web application</title>
<link rel="stylesheet"href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<scriptsrc="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<scriptsrc="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script>$(document).ready(function() {function bs_input_file() {$(".input-file").before(function() {if ( ! $(this).prev().hasClass('input-ghost') ) {var element = $("<input type='file' class='input-ghost' style='visibility:hidden; height:0'>");element.attr("name",$(this).attr("name"));element.change(function(){element.next(element).find('input').val((element.val()).split('\\').pop());});$(this).find("button.btn-choose").click(function(){element.click();});$(this).find("button.btn-reset").click(function(){element.val(null);$(this).parents(".input-file").find('input').val('');});$(this).find('input').css("cursor","pointer");$(this).find('input').mousedown(function() {$(this).parents('.input-file').prev().click();return false;});return element;}});}bs_input_file();$("#uploadBtn").on("click", function() {var url = "demo";var form = $("#sampleUploadFrm")[0];var data = new FormData(form);/* var data = {};data['key1'] = 'value1';data['key2'] = 'value2'; */$.ajax({type : "POST",encType : "multipart/form-data",url : url,cache : false,processData : false,contentType : false,data : data,success : function(msg) {var response = JSON.parse(msg);var status = response.status;if (status == 1) {alert("File has been uploaded successfully");} else {alert("Couldn't upload file");}},error : function(msg) {alert("Couldn't upload file");}});});});
</script>
</head><body><div class="container"><div class="col-md-8 col-md-offset-2"><h3>File Upload Example Using Servlet, Bootstrap and Ajax - jCombat</h3><form id="sampleUploadFrm" method="POST" action="#" enctype="multipart/form-data"><!-- COMPONENT START --><div class="form-group"><div class="input-group input-file" name="file"><span class="input-group-btn"><button class="btn btn-default btn-choose" type="button">Choose</button></span> <input type="text" class="form-control"placeholder='Choose a file...' /> <span class="input-group-btn"><button class="btn btn-warning btn-reset" type="button">Reset</button></span></div></div><!-- COMPONENT END --><div class="form-group"><button type="button" class="btn btn-primary pull-right" id="uploadBtn">Submit</button><button type="reset" class="btn btn-danger">Reset</button></div></form></div></div>
</body>
</html>

在home.jsp中，我们具有用于文件上传HTML表单，该表单使用Bootstrap。我们还在顶部添加了<script>标记，该标记具有jquery代码以使表单提交操作无效。

接下来让我们创建servlet类–

DemoFileUploadServlet.java

package com.jcombat.sample;import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;public class DemoFileUploadServlet extends HttpServlet {private static final long serialVersionUID = 1L;/*** @see HttpServlet#HttpServlet()*/public DemoFileUploadServlet() {super();}/*** @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)*/protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doPost(request, response);}/*** @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)*/protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {final String UPLOAD_DIRECTORY = "C:/uploads";if(ServletFileUpload.isMultipartContent(request)){try {List multiparts = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);for(FileItem item : multiparts){if(!item.isFormField()){File fileSaveDir = new File(UPLOAD_DIRECTORY);if (!fileSaveDir.exists()) {fileSaveDir.mkdir();}String name = new File(item.getName()).getName();item.write( new File(UPLOAD_DIRECTORY + File.separator + name));}}} catch (Exception e) {// exception handling}PrintWriter out = response.getWriter();out.print("{\"status\":1}");}}}

确保pom.xml文件添加了以下依赖项。

pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.jcombat.sample</groupId><artifactId>ServletFileUploadDemo</artifactId><version>0.0.1-SNAPSHOT</version><packaging>war</packaging><name>Servlet with Maven Demo</name><dependencies><dependency><groupId>javax.servlet</groupId><artifactId>javax.servlet-api</artifactId><version>3.0.1</version><scope>provided</scope></dependency><dependency><groupId>commons-fileupload</groupId><artifactId>commons-fileupload</artifactId><version>1.3</version></dependency></dependencies><build><sourceDirectory>src</sourceDirectory><plugins><plugin><artifactId>maven-war-plugin</artifactId><version>2.4</version><configuration><warSourceDirectory>WebContent</warSourceDirectory><failOnMissingWebXml>false</failOnMissingWebXml></configuration></plugin><plugin><artifactId>maven-compiler-plugin</artifactId><configuration><source>1.7</source><target>1.7</target></configuration></plugin></plugins></build>
</project>

执行应用程序

当执行应用程序时，我们将看到以下HTML表单。

选择文件，然后单击Submit 。成功上传文件后，我们会收到一条警告，提示“文件已成功上传”。

下载源代码

翻译自: https://www.javacodegeeks.com/2018/09/ajax-file-upload-servlet-bootstrap.html