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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><title>Java Image I/O API Guide: 3 - Writing Image I/O Applications</title></head><body bgcolor="#ffffff"> <table summary="layout" width="100%"><tr><td><!-- Bug in Communicator w/font: NavBar text disappears for Times 14pt pref. --><!-- font size="-1" --> <a href="imageio_guideTOC.fm.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/imageio_guideTOC.fm.html">CONTENTS</a> | <a href="goals.fm2.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/goals.fm2.html">PREV</a> | <a href="apps.fm2.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/apps.fm2.html">NEXT</a> <!-- | <a href="copyright.fm.html">INDEX</a> --><!-- /font --></td><td align=right><i>Java<sup><font size="-1">TM</font></sup></font> Image I/O API Guide</i></td></tr></table><br> <p><hr size="8" width="35%" align="left" noshade><br><U><B><FONT FACE="ARIAL,HELVETICA,TIMES ROMAN">CHAPTER</FONT>3</B></U><a name="5529"><!-- --></a><h1>Writing Image I/O Applications</h1><h2><a name="996883"><i>3.1 </i> Reading and Writing Images</a></h2><blockquote><a name="996884"><!-- --></a>The <code>javax.imageio.ImageIO</code> class provides a set of static convenience methods that perform most simple Image I/O operations.<p><a name="996885"><!-- --></a>Reading an image that is in a standard format (GIF, PNG, or JPEG) is simple:<p></blockquote><blockquote><pre>File f = new File("c:\images\myimage.gif");BufferedImage bi = ImageIO.read(f);</pre></blockquote><blockquote><a name="996887"><!-- --></a>The format of the image will be auto-detected by the API based on the contents of the file. Most image files contain a "magic number" in their first few bytes that identifies the file format. For formats that do not have a magic number, auto-detection may fail and somewhat more sophisticated application code will be needed.<p><a name="996888"><!-- --></a>Additional formats may be handled by installing JAR files containing plug-ins; the details are described in the next chapter. Once a plug-in has been installed, a new format will be understood automatically without any changes to the application code.<p><a name="996889"><!-- --></a>The set of formats available for reading can be obtained by calling <code>ImageIO.getReaderFormatNames</code>. This will return an array of <code>String</code>s containing the names of the available formats, such as "gif" and "png."<p><a name="996890"><!-- --></a>Writing an image in a supported format is equally simple:<p></blockquote><blockquote><pre>BufferedImage bi;File f = new File("c:\images\myimage.png");ImageIO.write(im, "png", f);</pre></blockquote><blockquote><a name="996892"><!-- --></a>The list of supported formats may be obtained by calling <code>ImageIO.getWriterFormatNames</code>.<p></blockquote><br><hr><!-- Bug in Communicator w/font: NavBar text disappears for Times 14pt pref. --><!-- font size="-1" --> <a href="imageio_guideTOC.fm.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/imageio_guideTOC.fm.html">CONTENTS</a> | <a href="goals.fm2.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/goals.fm2.html">PREV</a> | <a href="apps.fm2.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/apps.fm2.html">NEXT</a> <!-- | <a href="copyright.fm.html">INDEX</a> --><!-- /font --><hr><font size="-1"><i><A HREF="copyright.fm.html" tppabs="http://java.sun.com/j2se/1.4.2/docs/guide/imageio/spec/copyright.fm.html">Copyright</a> © 2001 Sun Microsystems, Inc. All Rights Reserved.</i></font></body><script language="JavaScript" src="s_code_remote.js" tppabs="http://java.sun.com/js/omi/jsc/s_code_remote.js"></script></html>⌨️ 快捷键说明
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