我们知道Java中有三种注释语句：
1.//用于单行注释。
2./*...*/用于多行注释，从/*开始，到*/结束，不能嵌套。
3./**...*/则是为支持jdk工具javadoc.exe而特有的注释语句。
javadoc工具能从java源文件中读取第三种注释，并能识别注释中用@标识的一些特殊变量（见表），制作成Html格式的类说明文档。 javadoc不但能对一个java源文件生成注释文档，而且能对目录和包生成交叉链接的html格式的类说明文档，十分方便。 注释中可以出现的关键字，以@开头：
@author 作者名
@version 版本标识
@parameter 参数名及其意义
@since 最早出现的JDK版本
@return 返回值
@throws 异常类及抛出条件
@deprecated 引起不推荐使用的警告
@see 交叉参考 下面是javadoc.exe的用法 C:\java>javadoc -help C:\java>javadoc -help usage: javadoc [options] [packagenames] [sourcefiles] [classnames] [@files]
-overview <file> Read overview documentation from HTML file
-public Show only public classes and members
-protected Show protected/public classes and members (default)
-package Show package/protected/public classes and members
-private Show all classes and members
-help Display command line options and exit
-doclet <class> Generate output via alternate doclet
-docletpath <path> Specify where to find doclet class files
-sourcepath <pathlist> Specify where to find source files
-classpath <pathlist> Specify where to find user class files
-exclude <pkglist> Specify a list of packages to exclude
-subpackages <subpkglist> Specify subpackages to recursively load
-breakiterator Compute 1st sentence with BreakIterator
-bootclasspath <pathlist> Override location of class files loaded by the bootstrap class loader
-source <release> Provide source compatibility with specified release
-extdirs <dirlist> Override location of installed extensions
-verbose Output messages about what Javadoc is doing
-locale <name> Locale to be used, e.g. en_US or en_US_WIN
-encoding <name> Source file encoding name
-J<flag> Pass <flag> directly to the runtime system Provided by Standard doclet:
-d <directory> Destination directory for output files
-use Create class and package usage pages
-version Include @version paragraphs
-author Include @author paragraphs
-docfilessubdirs Recursively copy doc-file subdirectories
-splitindex Split index into one file per letter
-windowtitle <text> Browser window title for the documenation
-doctitle <html-code> Include title for the overview page
-header <html-code> Include header text for each page
-footer <html-code> Include footer text for each page
-bottom <html-code> Include bottom text for each page
-link <url> Create links to javadoc output at <url>
-linkoffline <url> <url2> Link to docs at <url> using package list at <url2>
-excludedocfilessubdir <name1>:.. Exclude any doc-files subdirectories with given name.
-group <name> <p1>:<p2>.. Group specified packages together in overviewpage
-nocomment Supress description and tags, generate only declarations.
-nodeprecated Do not include @deprecated information
-noqualifier <name1>:<name2>:... Exclude the list of qualifiers from the output.
-nosince Do not include @since information
-nodeprecatedlist Do not generate deprecated list
-notree Do not generate class hierarchy
-noindex Do not generate index
-nohelp Do not generate help link
-nonavbar Do not generate navigation bar
-quiet Do not display status messages to screen
-serialwarn Generate warning about @serial tag
-tag <name>:<locations>:<header> Specify single argument custom tags
-taglet The fully qualified name of Taglet to register -tagletpath The path to Taglets
-charset <charset> Charset for cross-platform viewing of generated documentation.
-helpfile <file> Include file that help link links to
-linksource Generate source in HTML
-stylesheetfile <path> File to change style of the generated documentation
-docencoding <name> Output encoding name C:\java>
下面请看用javadoc生成的文档(请点击本页上面的观看演示链接）
生成文档： C:\java>javadoc JavadocDemo.java
Loading source file JavadocDemo.java...
Constructing Javadoc information...
Standard Doclet version 1.4.2_03
Generating constant-values.html...
Building tree for all the packages and classes...
Building index for all the packages and classes...
Generating overview-tree.html...
Generating index-all.html...
Generating deprecated-list.html...
Building index for all classes...
Generating allclasses-frame.html...
Generating allclasses-noframe.html...
Generating index.html...
Generating packages.html...
Generating JavadocDemo.html...
JavadocDemo.java:11: warning - Tag @see: reference not found: javax.swing.Japplet
Generating serialized-form.html...
Generating package-list...
Generating help-doc.html...
Generating stylesheet.css...
1 warning C:\java>
附源文件：
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
/**
*JavadocDemo.java,一个显示JavaDoc注释的Applet
*<p>注意这只是HelloApplet的一个带注释的版本
*@see java.applet.Applet
*@see javax.swing.Japplet
*/ public class JavadocDemo extends Applet{ /** init()是一个Applet方法，由浏览器调用进行初始化
* 只调用一次
* @return 无
*/
public void init(){
//创建并添加一个按钮
//其它什么也不做
Button b;
b=new Button("Hello");
add(b);
show();
} /** paint() 是一个AWT组件方法，在组件要绘制时调用，只
* 是在Applet的窗口中画带色的方框。
* 参数 g一个java.awt.Graphics
* 用在所有绘制方法中
*/ public void paint(Graphics g){
int w=getSize().width,h=getSize().height;
g.setColor(Color.yellow);
g.fillRect(0,0,w/2,h);
g.setColor(Color.green);
g.fillRect(w/2,0,w,h);
g.setColor(Color.black);
g.drawString("Welcome to Java",50,50);
} /** show()用于使组件可见，此方法在
* JDK1.1中被归入不推荐使用
*@since 1.0
*deprecated换用setVisible(true)
*/ public void show(){
//由于覆盖了show(),此applet 不能显示
} /** Applet必须有一个公共的无参数构造方法
*@throws java.lang.IllegalArgumentException
*/ public JavadocDemo(){
if(new java.util.Date().getDay()==0){
throw new IllegalArgumentException("Never on a Sunday");
}
}
}