ajax实现图片的回显功能

wuchangjian2021-11-03 23:39:18编程学习

前端页面

给文件上传域绑定一个改变事件

<tr>
   <td class="three">图片介绍</td>
   <td> <br><div id="imgDiv" style="display:block; width: 40px; height: 50px;"></div><br><br><br><br>
    <input type="file" id="pimage" name="pimage" onchange="fileChange()" >
    <span id="imgName" ></span><br>

    </td>
</tr>

选择图片后通过ajax发送请求到服务端,把图片进行存储并且返回json数据,使得图片回显

<script type="text/javascript">
        function fileChange(){
			$.ajaxFileUpload({
				url:"${pageContext.request.contextPath}/prod/ajaxImg.action",
				secureuri: false,
				fileElementId: 'pimage',
				dataType:"json",
				success:function (obj) {
					//清空div
					$("#imgDiv").empty();
					//创建一个图片的标签
					var imgObj = $("<img>");
					alert(obj.imgurl);
					imgObj.attr("src","/image_big/"+obj.imgurl);
					imgObj.attr("width","100px");
					imgObj.attr("height","100px");
					//将图片追加到imgDiv
					$("#imgDiv").append(imgObj);
				}
			});
        }
    </script>

这里采用的$.ajaxFileUpload是一个命名为ajaxfileupload.js需要引入到js包下面,直接赋值下面代码即可


jQuery.extend({

    createUploadIframe: function(id, uri)
	{
			//create frame
            var frameId = 'jUploadFrame' + id;
            
            if(window.ActiveXObject) {
                var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
                if(typeof uri== 'boolean'){
                    io.src = 'javascript:false';
                }
                else if(typeof uri== 'string'){
                    io.src = uri;
                }
            }
            else {
                var io = document.createElement('iframe');
                io.id = frameId;
                io.name = frameId;
            }
            io.style.position = 'absolute';
            io.style.top = '-1000px';
            io.style.left = '-1000px';

            document.body.appendChild(io);

            return io			
    },
    createUploadForm: function(id, fileElementId)
	{
		//create form	
		var formId = 'jUploadForm' + id;
		var fileId = 'jUploadFile' + id;
		var form = $('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');	
		var oldElement = $('#' + fileElementId);
		var newElement = $(oldElement).clone();
		$(oldElement).attr('id', fileId);
		$(oldElement).before(newElement);
		$(oldElement).appendTo(form);
		//set attributes
		$(form).css('position', 'absolute');
		$(form).css('top', '-1200px');
		$(form).css('left', '-1200px');
		$(form).appendTo('body');		
		return form;
    },

    ajaxFileUpload: function(s) {
        // TODO introduce global settings, allowing the client to modify them for all requests, not only timeout		
        s = jQuery.extend({}, jQuery.ajaxSettings, s);
        var id = s.fileElementId;        
		var form = jQuery.createUploadForm(id, s.fileElementId);
		var io = jQuery.createUploadIframe(id, s.secureuri);
		var frameId = 'jUploadFrame' + id;
		var formId = 'jUploadForm' + id;		
        // Watch for a new set of requests
        if ( s.global && ! jQuery.active++ )
		{
			jQuery.event.trigger( "ajaxStart" );
		}            
        var requestDone = false;
        // Create the request object
        var xml = {}   
        if ( s.global )
            jQuery.event.trigger("ajaxSend", [xml, s]);
        // Wait for a response to come back
        var uploadCallback = function(isTimeout)
		{			
			var io = document.getElementById(frameId);
            try 
			{				
				if(io.contentWindow)
				{
					 xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
                	 xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
					 
				}else if(io.contentDocument)
				{
					 xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
                	xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
				}						
            }catch(e)
			{
				jQuery.handleError(s, xml, null, e);
			}
            if ( xml || isTimeout == "timeout") 
			{				
                requestDone = true;
                var status;
                try {
                    status = isTimeout != "timeout" ? "success" : "error";
                    // Make sure that the request was successful or notmodified
                    if ( status != "error" )
					{
                        // process the data (runs the xml through httpData regardless of callback)
                        var data = jQuery.uploadHttpData( xml, s.dataType );    
                        // If a local callback was specified, fire it and pass it the data
                        if ( s.success )
                            s.success( data, status );
    
                        // Fire the global callback
                        if( s.global )
                            jQuery.event.trigger( "ajaxSuccess", [xml, s] );
                    } else
                        jQuery.handleError(s, xml, status);
                } catch(e) 
				{
                    status = "error";
                    jQuery.handleError(s, xml, status, e);
                }

                // The request was completed
                if( s.global )
                    jQuery.event.trigger( "ajaxComplete", [xml, s] );

                // Handle the global AJAX counter
                if ( s.global && ! --jQuery.active )
                    jQuery.event.trigger( "ajaxStop" );

                // Process result
                if ( s.complete )
                    s.complete(xml, status);

                jQuery(io).unbind()

                setTimeout(function()
									{	try 
										{
											$(io).remove();
											$(form).remove();	
											
										} catch(e) 
										{
											jQuery.handleError(s, xml, null, e);
										}									

									}, 100)

                xml = null

            }
        }
        // Timeout checker
        if ( s.timeout > 0 ) 
		{
            setTimeout(function(){
                // Check to see if the request is still happening
                if( !requestDone ) uploadCallback( "timeout" );
            }, s.timeout);
        }
        try 
		{
           // var io = $('#' + frameId);
			var form = $('#' + formId);
			$(form).attr('action', s.url);
			$(form).attr('method', 'POST');
			$(form).attr('target', frameId);
            if(form.encoding)
			{
                form.encoding = 'multipart/form-data';				
            }
            else
			{				
                form.enctype = 'multipart/form-data';
            }			
            $(form).submit();

        } catch(e) 
		{			
            jQuery.handleError(s, xml, null, e);
        }
        if(window.attachEvent){
            document.getElementById(frameId).attachEvent('onload', uploadCallback);
        }
        else{
            document.getElementById(frameId).addEventListener('load', uploadCallback, false);
        } 		
        return {abort: function () {}};	

    },

    uploadHttpData: function( r, type ) {
        var data = !type;
        data = type == "xml" || data ? r.responseXML : r.responseText;
        // If the type is "script", eval it in global context
        if ( type == "script" )
            jQuery.globalEval( data );
        // Get the JavaScript object, if JSON is used.
        if ( type == "json" )
            eval( "data = " + data );
        // evaluate scripts within html
        if ( type == "html" )
            jQuery("<div>").html(data).evalScripts();
			//alert($('param', data).each(function(){alert($(this).attr('value'));}));
        return data;
    }
})

 

服务端

主要采用了spring mvc框架,并且利用了多部件解析器

//异步ajax的图片回显功能
    @ResponseBody
    @RequestMapping("/ajaxImg.action")
    public Object ajaximg(MultipartFile pimage,HttpServletRequest request){
        //提取生成文件名UUID+文件名后缀   保证图片可以重复
        String saveFileName= FileNameUtil.getUUIDFileName()+FileNameUtil.getFileType(pimage.getOriginalFilename());
        //得到项目中图片的存储路径
        String path = request.getServletContext().getRealPath("/image_big");
        //转存文件
        try {
            pimage.transferTo(new File(path+File.separator+saveFileName));
        } catch (IOException e) {
            e.printStackTrace();
        }
        //返回一个json对象
        JSONObject object = new JSONObject();
        object.put("imgurl",saveFileName);
        return object.toString();
    }

这里利用到了一个文件名的工具类,主要是生成一个随机的文件名和对文件名后缀的截取

public class FileNameUtil {
	//根据UUID生成文件名
	public static String getUUIDFileName() {
		UUID uuid = UUID.randomUUID();
		return uuid.toString().replace("-", "");
	}
	//从请求头中提取文件名和类型
	public static String getRealFileName(String context) {
		// Content-Disposition: form-data; name="myfile"; filename="a_left.jpg"
		int index = context.lastIndexOf("=");
		String filename = context.substring(index + 2, context.length() - 1);
		return filename;
	}
	//根据给定的文件名和后缀截取文件名
	public static String getFileType(String fileName){
		//9527s.jpg
		int index = fileName.lastIndexOf(".");
		return fileName.substring(index);
	}
}

另外json转换工具用的是下面的,其中要注意要返回json数据格式时必须要用toString方法

<dependency>
     <groupId>org.json</groupId>
     <artifactId>json</artifactId>
     <version>20140107</version>
</dependency>

最终效果展示

相关文章

Webpack 使用

Webpack 使用

 1.1webpack是什么 webpack 是一种前端资源构建工具&#...

能带计算理论与实践(平面波方法以及其推广)

总结:在以平面波基组为基础计算能带的框架下,难点都是对周期性...

SpringBoot常用注解及作用

目录 控制器controller常用注解 主函数MainApplicatio...

浮动路由配置实验

浮动路由配置实验

思路先配置直连路由,然后再配置静态路由,最后配置浮动路由 一...

发表评论    

◎欢迎参与讨论,请在这里发表您的看法、交流您的观点。