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>