display dynamic or static images

How can we display dynamic or static images that can be provided as an array of bytes

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Added by tm_jee, last edited by Ted Husted on Jul 22, 2006  (view change)

To display an image represented as an array of bytes

• Reference an Action for the image src attribute
• Provide a helper method on the Action to return an array of bytes
• Provide a Result Type that renders the array to the response

Reference an Action

MyAction.jsp

<img src="/myWebAppContext/myAction.do" />

Provide Helper Methods

MyAction.java

public class MyAction extends ActionSupport {
  public String doDefault() {
    return "myImageResult";
  }

  public byte[] getMyImageInBytes() { .... }

  public String getMyContentType() { ... }
  public String getMyContentDisposition() { ... }
  public int getMyContentLength() { .... }
  public int getMyBufferSize() { ... }

}

Provide a Custom Result Type

struts.xml

<struts>

    ...
    <result-types>
        <result-type name="myBytesResult" class="MyBytesResult" />
    </result-types>
    ...
    <action name="myAction" class="MyAction">
        <result name="myImageResult" type="myBytesResult">
            <param name="contentType">${myContentType}</param>
            <param name="contentDisposition">${myContentDisposition}</param>
            <param name="contentLength">${myContentLength}</param>
            <param name="bufferSize">${myBufferSize}</param>
        <result>
    </action>
    ...

</struts>

MyBytesResult.java

public class MyBytesResult implements Result {

	public void execute(ActionInvocation invocation) throws Exception {

		MyAction action = (MyAction) invocation.getAction();
		HttpServletResponse response = ServletActionContext.getResponse();

                response.setContentType(action.getContentType());
		response.setContentLength(action.getContentLength());

		response.getOutputStream().write(action.getImageInBytes());
		response.getOutputStream().flush();
	}

}

From ： http://struts.apache.org/2.x/docs/how-can-we-display-dynamic-or-static-images-that-can-be-provided-as-an-array-of-bytes.html

评论

1 楼 wenquan4004 2009-04-02  

我也用这个做了一个MyBytesResult但是报OutputStream已经被call了
我是这么做的我的一个java类里有多个action，其中一个action处理图片，其它处理数据
程序是先请求一个action然后返回jsp页面，在该页面上有个<img src="请求图片处理action">
但是总是报response.getOutputStream()已经被调用了