Js上传图片并生成缩略图

Js上传图片并显示缩略图的流程为
Js选择文件->Jquery上传图片->服务器接收图片流->存储图片->返回结果到Js端->显示缩略图

本文上传图片所用的Js库是ajaxfileupload,下载地址：https://files.cnblogs.com/files/yujie365/ajaxfileupload.js，Html布局采用bootstrap.
后端处理流程使用Java中的Spring框架进行处理

前面页面处理流程

1,Html页面定义File：

2,选择图片并上传:
*绑定fileimage控件的change事件：$("#fileimage").bind("change", uploadFileImage);
*上传图片:
function uploadFileImage() {
var objUrl = getObjectURL(this.files[0]);
// 上传图片
uploadFile("uploadimage/fileimage", "fileimage", function(result) {

});	
 }


 //uploadUrl:服务器用于接收图片的接口
 //fileElementID:file控件的id
 //callback:图片上传完成后的回调方法。
 function uploadFile(uploadUrl, fileElementID, callback) {	
$.ajaxFileUpload({
	url : uploadUrl,
	secureuri : false,
	type : 'post',
	fileElementId : fileElementID,
	dataType : 'JSON',
	success : function(data) {
                    //data:服务器返回的结果
		if (data&& callback != null) {
		   callback(data);
		}
	},
	error : function(data, status, e) {

	}
});
  }

*显示缩略图:
更新上面uploadFileImage方法为下面代码:
function uploadFileImage() {
var objUrl = getObjectURL(this.files[0]);
// 上传图片
uploadFile("uploadimage/fileimage", "fileimage", function(result) {
// 显示缩略图
console.log("objUrl = " + objUrl);
if (objUrl) {
$("#fileimage_thumbnail").attr("src", objUrl);
}
});
}

后台Java处理流程

1,后台接收图片的方法如下:
@RequestMapping(value = "uploadimage/fileimage")
public void uploadPicture(HttpServletRequest request) {

	try {
		String filePath = uploadFile(request, pictureUploadService);
		if (!Tools.isEmptyString(filePath)) {
			setResult(filePath);
			logHelper.info("图片上传成功...");
		} else {
			setResult(
					MessageManager.getInstance().getMessage(
							"pictureuploadfailed"),
					ResultType.Error);
			logHelper.info("图片上传失败...");
		}
	} catch (IllegalStateException e) {
		logHelper.warn("图片保存失败:" + e.getMessage());
	} catch (IOException e) {
		logHelper.warn("图片保存失败:" + e.getMessage());
	}	
}

2,存储图片处理流程
private String uploadFile(HttpServletRequest request,IUploadFile uploadFile) throws IllegalStateException,
IOException {
String filePath="";

	CommonsMultipartResolver multipartResolver = new CommonsMultipartResolver(
			request.getSession().getServletContext());

	if (multipartResolver.isMultipart(request)) {
		MultipartHttpServletRequest multipartHttpServletRequest = (MultipartHttpServletRequest) request;
		
		Iterator<String> fileNames = multipartHttpServletRequest
				.getFileNames();

		while (fileNames.hasNext()) {
			MultipartFile file = multipartHttpServletRequest
					.getFile(fileNames.next().toString());

			if (file != null) {
				filePath = uploadFile.uploadFile(file);
				if (!Tools.isEmptyString(filePath)) {
					setResult(filePath);
				} else {
					setResult(
							MessageManager.getInstance().getMessage(
									"pictureuploadfailed"),
							ResultType.Error);
				}
			}
		}
	}
	
	return filePath;
}

public interface IUploadFile {
public String uploadFile(IMultipartFile multipartFile) throws IllegalStateException, IOException ;

}

@Service
public class PictureUploadService extends BaseService implements IUploadFile {

/**
 * 上传图片
 * @param multipartFile
 *            用户所上传的图片文件
 * @return
 * @throws IllegalStateException
 * @throws IOException
 */
@Override
public String uploadFile(MultipartFile multipartFile) throws IllegalStateException, IOException {
	String relativePath = Helpers.getImageFolderPath();

	String imageSavedPath = IOTools.transferFile(multipartFile,
			ConfigHelper.IMAGE_SAVED_PATH, relativePath);

	logger.info("图片保存路径:" + imageSavedPath);

	return imageSavedPath;
}

}

package com.weijiazhe.utils;

import java.io.File;
import java.io.IOException;
import java.util.Dictionary;

import org.springframework.web.multipart.MultipartFile;

import com.weijiazhe.weijiazheutils.ConfigHelper;

public class IOTools {

/**
 * 转移文件
 * 
 * @param multipartFile
 * @param fileAbsoluteSavedPath
 * @param relativePath
 * @return
 * @throws IllegalStateException
 * @throws IOException
 */
public static String transferFile(MultipartFile multipartFile,
		String fileAbsoluteSavedPath, String relativePath)
		throws IllegalStateException, IOException {
	if (!Tools.isEmptyString(relativePath)) {
		String fileName = Tools.getGuid();
		String prefix = IOTools.getPrefix(multipartFile
				.getOriginalFilename());

		relativePath += "\\" + fileName + prefix;

		String fileSavedPath = fileAbsoluteSavedPath + relativePath;
		
		File file = new File(fileSavedPath);
	
		//文件不存在则创建文件.
		if(!file.exists()){
			//String dirName=file.getAbsolutePath();
			//if(file.isDirectory()){
				file.mkdirs();
			//}
			//fileSavedPath+="\\" + fileName + prefix;
			//file=new File(fileAbsoluteSavedPath);
			//file.createNewFile();
		}

		multipartFile.transferTo(file);
	}

	return relativePath;
}

}