图片使用base64图片数据格式上传（后台使用springMVC）

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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" onclick="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;@Controllerpublic 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");

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