从struts2操作变量中的路径以jsp显示图像

Question

i have a struts2 action which has a variable for an image which i want to display in a jsp page. when i display the value of the variable using the following:

<s:property value="variableName" />

i get the absolute path of the image file.

but when i try the following:

<img src='<s:property value="variableName" />' />

i get a blank there. i have even tried the following:

<img src="${variableName}" />

EDIT: i have done some thinking. the path of the image which is set is in temp folder of tomcat. is it because of that that i am unable to access it?

to no effect. what may be the issue in this?

Answer 1

The src of the img tag must contain an absolute path, then only it can point to the image file from the client machine.

If the variableName contains an absolute path like this

http://localhost/images/pics/icon.gif

The img will finds the image from the server. Thus available always an hence you can use this.

<img src="${variableName}"/>

If the variableName is a relative path ie; something that's recognisable for the server.

/images/pics/icon.gif

The above path will be identified by the server but it wont be identified from the remote machine. In that case you need to have this

<img src="<c:url value=variableName/>" />

Answer 2

Always keep in mind when doing web development what you have in server context and what travels to the client browser. If you do what you are suggesting, you will render and send to the client something like this:

<img src="c:\my_local_directory\some_image.jpg"></img>

Which means nothing to the client browser, which is surely executing in some other machine.

You should store your images somewhere where your application server can show them, and give always paths that are relative to your web application. For example, if you have stored some_image.jpg straight in your my-app.war file, something like:

<img src="/my-app/some_image.jpg"></img>

will always work. If you need to refine that image (imagine you need to put a watermark on it before) or need to recover its contents from somewhere (a BLOB in a database or something like that), you will need an entire new action in order to do it, for example:

<img src="/my-app/ImageAction.action?image=some_image"></img>