其实不使用ImageIO，就是用一般的BufferedOutputStream+byte[] buffer也可以
关键在于通过response设置页面的MIME Type，自行Google~~~
源代码直接帖了。。。
ImageTag.java
public class ImageTag extends SimpleTagSupport {
private String fileName;
private HttpServletResponse response;
private String imageType;
public void setImageType(String imageType) {
this.imageType = imageType;
}
public void setFileName(String fileName) {
this.fileName = fileName;
}
public void setResponse(HttpServletResponse response) {
this.response = response;
}
@Override
public void doTag() throws JspException, IOException {
response.setContentType("image/" + imageType); // This is necessary!!!
BufferedImage image = null;
BufferedOutputStream outputStream = null;
try {
File imageFile = new File(fileName);
Image src = ImageIO.read(imageFile);
int width = src.getWidth(null);
int height = src.getHeight(null);
image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
image.getGraphics().drawImage(src, 0, 0, width, height, null);
outputStream = new BufferedOutputStream(response.getOutputStream());
ImageIO.write(image, imageType, outputStream);
outputStream.flush(); // write the content from the buffer to the page
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
if (outputStream != null)
outputStream.close();
}
}
}
tagext.tld
<?xml version="1.0" encoding="UTF-8"?>
<taglib xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-jsptaglibrary_2_0.xsd"
version="2.0"> <description>Tag extensions, my customized tag library.</description>
<display-name>xxx ext tags</display-name>
<tlib-version>1.0</tlib-version>
<short-name>ext</short-name>
<uri>http://tags.xxx.com/ext</uri> <tag>
<description>
Load the specified image file and display it on the page.
</description>
<name>image</name>
<tag-class>com.v1.ex120.ImageTag</tag-class>
<body-content>empty</body-content> <attribute>
<description>
The file extension of the image file.
</description>
<name>imageType</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute> <attribute>
<description>
The URI of the image file on the disk.
</description>
<name>fileName</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute> <attribute>
<description>
The HttpServletResponse of the display page.
Normally you'd use the response object of the page
in which this tag is used.
</description>
<name>response</name>
<required>true</required>
<rtexprvalue>true</rtexprvalue>
</attribute>
</tag> </taglib>
imagetag.jsp
<%@ page language="java" contentType="text/html; charset=GBK"
pageEncoding="GBK"%>
<%@ taglib uri="http://tags.xxx.com/ext" prefix="ext" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GBK">
<title>Insert title here</title>
</head>
<body>
<ext:image response="${pageContext.response }" fileName="D:\qq.png" imageType="PNG"/>
</body>
</html>