How to use HTML to upload images on the page and share the sample code for display

html页面：

本功能实现图片上传并显示，点击“查看”按钮也显示图片

<p class="form-group">
<label class="col-md-2 control-label">缩略图</label>
<p class="col-md-2">
<input type="hidden" name="news.thumbnail_atta_id" value="${news.thumbnail_atta_id!}" id="thumbnail_atta_id"/>
<p class="col-md-2">
@ if (!isEmpty(news.thumbnail_atta_id)) {
<p class="row" style="margin-bottom:5px;">
<button type="button" class="btn btn-primary" id="showThumbnail">查看</button>
</p>
@ }
<p class="row">
<span class="btn btn-success fileinput-button">
    <i class="glyphicon glyphicon-plus"></i>
    <span>上传...</span>
    <input id="fileupload" type="file" data-url="/atta/upload/news-thumbnail" multiple>
</span>
</p>
</p>
<p>
<img src="" id="thumbnail" width="150" height="100" style="display:none;"/>
</p>
</p>
</p>

js代码：

<script type="text/JavaScript">
//缩略图文件上传
$(&#39;#fileupload&#39;).fileupload({
dataType: &#39;json&#39;,
add: function(e, data) {
var acceptFileTypes = /(\.|\/)(gif|jpe?g|png)$/i;
if(data.originalFiles[0][&#39;type&#39;].length && !acceptFileTypes.test(data.originalFiles[0][&#39;type&#39;])) {
alert(&#39;请上传图片格式的文件！&#39;)
} else {
data.submit();
}
},
done: function (e, data) {
$(&#39;#thumbnail_atta_id&#39;).val(data.result.id);
$(&#39;#thumbnail&#39;).attr(&#39;src&#39;, data.result.url).show();
}
});
//查看缩略图
$(&#39;#showThumbnail&#39;).click(function(){
var src = $(&#39;#thumbnail&#39;).attr(&#39;src&#39;);
var id=$(&#39;#thumbnail_atta_id&#39;).val();
if (!src) {
$.get(&#39;/atta/show/${news.thumbnail_atta_id!}&#39;, function(res) {
var url=localurl+res[0].url;
//var url = "www.baidu.com/img/bd_logo1.png";
alert(url);
$(&#39;#thumbnail&#39;).attr(&#39;src&#39;, url).show();
}, &#39;json&#39;)
}
})
 </script>

Java代码：

Controller类：

/**
* 上传并返回附件ID及URL
*/
public void upload() {
UploadFile file = getFile();
String fileName = file.getFileName();
String fileSuffix = getSuffix(fileName);
String module = getPara(0);
String category = getPara(1);

String id = AttachmentService.me.uploadFile(file, module, category);
Map<String, Object> json = new HashMap<String, Object>();
json.put("id", id);
json.put("url", "/upload/" + category + "/" + module + "/" + id + fileSuffix);
json.put("name", fileName);

renderJson(json);
}
/**
* 返回给定ID的附件的访问URL
*/
public void show() {
String ids = getPara();
if (null == ids) {
ids = getPara("ids");
}
String[] idArr = ids.split(",");

StringBuffer sql = new StringBuffer();
sql.append(" select * from attachment where id in ( ");
for (int index = 0; index < idArr.length; index++) {
sql.append(" ? ");
if (index != idArr.length - 1) {
sql.append(" , ");
}
}
sql.append(" ) ");

List<Map<String, Object>> json = new ArrayList<Map<String,Object>>();
List<Attachment> list =  Attachment.me.find(sql.toString(), (Object[])idArr);

//转换成JsonArray
String url = null;
for (Attachment atta : list) {
url = getAttaURL(atta);
Map<String, Object> item = new HashMap<String, Object>();
item.put("id", atta.getStr("id"));
item.put("url", url);
item.put("name", atta.getStr("name"));
json.add(item);
}
renderJson(json);
}

private String getAttaURL(Attachment atta) {
StringBuffer path = new StringBuffer();
path.append(File.separator + "upload" + File.separator);
path.append(atta.getStr("category"));
path.append(File.separator);
path.append(atta.getStr("module"));
path.append(File.separator);
path.append(atta.getStr("id"));
path.append(getSuffix(atta.getStr("name")));
return path.toString();
}

private String getSuffix(String name) {
return name.replaceAll(".*(\\..*)", "$1");
}

service类：

/**
* 上传文件
* @param file
 
uploadFile
* @param module
模块，如news/cases/doctor/
* @param category
分类，如缩略图thumbnail/头像avatar/幻灯片ppt
* @return
 
附件主键
* @throws IOException 
*/
public String uploadFile(UploadFile file, String module, String category) {
String attachmentId = CommonUtils.getUUID();
File f = file.getFile();
new Attachment().set("id", attachmentId)
.set("name", file.getOriginalFileName())
.set("size", f.length())
.set("content_type", file.getContentType())
.set("module", module)
.set("category", category)
.set("upload_time", new Date())
.save();
try {
//重命名
String dirPath = file.getSaveDirectory();
File renamedFile = new File(dirPath + attachmentId + file.getOriginalFileName().replaceAll(".*(\\..*)", "$1"));
FileUtils.moveFile(f, renamedFile);
//PPT需要转换成图片，拷贝一份到转换目录(/upload/trans/ppt)
if (category.equals("ppt")) {
FileUtils.copyFileToDirectory(renamedFile, new File(dirPath + "trans/ppt/"), true);
}
//拷贝到对应的目录下
FileUtils.moveToDirectory(renamedFile, new File(dirPath + category + File.separator + module), true);
} catch(Exception e) {
e.printStackTrace();
}
return attachmentId;
}

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