图片使用base64图片数据格式上传（后台使用springMVC）

Dear 丶 2022-06-08 08:27 238阅读 0赞

一、前台JSP页面

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
    <%@ taglib uri="http://java.sun.com/jsp/jstl/fmt" prefix="fmt" %>
    <c:set var="ctx" value="${pageContext.request.contextPath}" />
    <!DOCTYPE html>
    <html>    
    <head>
    	<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
    	<title>文件上传</title>
    	<script type="text/javascript"  src="${ctx}/js/jquery-2.1.4/jquery-2.1.4.js"></script>	
    	<script type="text/javascript">
    
        //通过FileReader.readAsDataURL获取base64数据
        function uploadFile(file){
            var f = document.getElementById("myImage").files[0];
            var reader = new FileReader(); //新建一个FileReader
            reader.readAsDataURL(f);  // 读取文件base64数据
            reader.onload = function(e){ //数据读取完成产生onload事件
                var data = e.target.result; //获取数据
                if (data.lastIndexOf('data:base64') != -1) {
                      data = data.replace('data:base64', 'data:image/jpeg;base64');
                } else if (data.lastIndexOf('data:,') != -1) {
                      data = data.replace('data:,', 'data:image/jpeg;base64,');
                }
    
                if(isCanvasSupported()){
                     ajaxUploadBase64File(data);
                }else{
                     alert("您的浏览器不支持");
                }
    
            };
    
            reader.onerror = function(){
                console.log("上传失败了 ");
            }
    
            
        }
    
        //ajax异步上传
        function ajaxUploadBase64File(base64Data){
            var url = "${ctx}/upload/uploadBase64";
            $.ajax({
                url:url,
                type:"post",
                data:{base64Data:base64Data},
                success:function(data){
                    if(data == "success"){
                       alert("上传成功");
                    }else{
                        alert("上传失败");
                    }
                },
                error:function(){
                    alert("上传失败");
                }
            });
        }; 
    
    
        //是否支持canvas
        function isCanvasSupported(){
            var elem = document.createElement('canvas');
            return !!(elem.getContext && elem.getContext('2d'));
        };
    	   
    	</script>
    
    </head>
    
    <body>
        <input type="file" id="myImage" name="myImage"/> 
        <input type="button" οnclick="uploadFile();" value="上传">
    </body>
    </html>

二、后台Controller

package org.nercita.bcp.upload;
    
    import java.io.File;
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.UUID;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.apache.commons.io.FileUtils;
    import org.springframework.stereotype.Controller;
    import org.springframework.util.Base64Utils;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RequestMethod;
    import org.springframework.web.bind.annotation.RequestParam;
    import org.springframework.web.bind.annotation.ResponseBody;
    import org.springframework.web.multipart.commons.CommonsMultipartFile;
    
    @Controller
    public class UploadController {	
    
        @RequestMapping("/upload/uploadImage")
        public String uploadImagePage(){
    	return "/upload/uploadImage";
        }
    	
    	
        @RequestMapping(value="/upload/uploadBase64",method=RequestMethod.POST)
        @ResponseBody
        public String base64UpLoad(@RequestParam String base64Data, HttpServletRequest request, HttpServletResponse response){  	       
            try{  	           
                String dataPrix = "";
                String data = "";	       
                if(base64Data == null || "".equals(base64Data)){
                    throw new Exception("上传失败，上传图片数据为空");
                }else{
                    String [] d = base64Data.split("base64,");
                    if(d != null && d.length == 2){
                        dataPrix = d[0];
                        data = d[1];
                    }else{
                        throw new Exception("上传失败，数据不合法");
                    }
                }	          
                String suffix = "";
                if("data:image/jpeg;".equalsIgnoreCase(dataPrix)){//data:image/jpeg;base64,base64编码的jpeg图片数据
                    suffix = ".jpg";
                } else if("data:image/x-icon;".equalsIgnoreCase(dataPrix)){//data:image/x-icon;base64,base64编码的icon图片数据
                    suffix = ".ico";
                } else if("data:image/gif;".equalsIgnoreCase(dataPrix)){//data:image/gif;base64,base64编码的gif图片数据
                    suffix = ".gif";
                } else if("data:image/png;".equalsIgnoreCase(dataPrix)){//data:image/png;base64,base64编码的png图片数据
                    suffix = ".png";
                }else{
                    throw new Exception("上传图片格式不合法");
                }
                String tempFileName = UUID.randomUUID().toString() + suffix;	            
    
                //因为BASE64Decoder的jar问题，此处使用spring框架提供的工具包
                byte[] bs = Base64Utils.decodeFromString(data);
                try{
                    //使用apache提供的工具类操作流
                	
                	System.out.println(request.getServletContext().getRealPath("/upload"));
                    FileUtils.writeByteArrayToFile(new File(request.getServletContext().getRealPath("/upload"), tempFileName), bs);  
                }catch(Exception ee){
                    throw new Exception("上传失败，写入文件失败，"+ee.getMessage());
                }	           	          
                return "success";	           
            }catch (Exception e) {  	          
                return "error";
            }  	     
        }	
    }

本文使用的是FileRead的readAsDataURL获取base64的图片编码数据，通常我们 使用canvas画布在html的dom元素中所绘的图行，也可以使用 canvas的toDataUrl转换成base64编码的图片数据进行上传，具体获取方式如下：

var mycanvas = document.getElementById("mycanvas");  
     var imageBase64Data  = mycanvas.toDataURL("image/png");