Java-ServletOutputStream

/**
 * Provides an output stream for sending binary data to the
 * client. A <code>ServletOutputStream</code> object is normally retrieved
 * via the {@link ServletResponse#getOutputStream} method.
 *
 * <p>This is an abstract class that the servlet container implements.
 * Subclasses of this class
 * must implement the <code>java.io.OutputStream.write(int)</code>
 * method.
 *
 *
 * @author 	Various
 * @version 	$Version$
 *
 * @see 	ServletResponse
 *
 */
//提供一个输出流来发送二进制数据给客户端，Servlet容器会实现这个类，这个类的子类一定要实现java.io.OutputStream.write(int)方法
public abstract class ServletOutputStream extends OutputStream {

    private static final String LSTRING_FILE = "javax.servlet.LocalStrings";
    private static ResourceBundle lStrings =
	ResourceBundle.getBundle(LSTRING_FILE);
    /**
     * Does nothing, because this is an abstract class.
     */
    //抽象类的构造函数
    protected ServletOutputStream() { }
    /**
     * Writes a <code>String</code> to the client,
     * without a carriage return-line feed (CRLF)
     * character at the end.
     * @param s			the <code>String</code> to send to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //向客户端写string
    public void print(String s) throws IOException {
    	if (s==null) s="null";
    	int len = s.length();
    	for (int i = 0; i < len; i++) {
    		char c = s.charAt (i);
    		// XXX NOTE:  This is clearly incorrect for many strings,
    		// but is the only consistent approach within the current
    		// servlet framework.  It must suffice until servlet output
    		// streams properly encode their output.
    		//
    		if ((c & 0xff00) != 0) {	// high order byte must be zero
    			String errMsg = lStrings.getString("err.not_iso8859_1");
    			Object[] errArgs = new Object[1];
    			errArgs[0] = new Character(c);
    			errMsg = MessageFormat.format(errMsg, errArgs);
    			throw new CharConversionException(errMsg);
    		}
    		write (c);
    	}
    }
    /**
     * Writes a <code>boolean</code> value to the client,
     * with no carriage return-line feed (CRLF)
     * character at the end.
     * @param b			the <code>boolean</code> value
     *				to send to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //向客户端写boolean
    public void print(boolean b) throws IOException {
    	String msg;
    	if (b) {
	    msg = lStrings.getString("value.true");
    	} else {
	    msg = lStrings.getString("value.false");
    	}
    	print(msg);
    }
    /**
     * Writes a character to the client,
     * with no carriage return-line feed (CRLF)
     * at the end.
     * @param c			the character to send to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //向客户端写字符
    public void print(char c) throws IOException {
    	print(String.valueOf(c));
    }
    /**
     * Writes an int to the client,
     * with no carriage return-line feed (CRLF)
     * at the end.
     * @param i			the int to send to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //写int
    public void print(int i) throws IOException {
    	print(String.valueOf(i));
    }
    /**
     * Writes a <code>long</code> value to the client,
     * with no carriage return-line feed (CRLF) at the end.
     * @param l			the <code>long</code> value
     *				to send to the client
     * @exception IOException 	if an input or output exception
     *				occurred
     */
    //写long
    public void print(long l) throws IOException {
    	print(String.valueOf(l));
    }
    /**
     * Writes a <code>float</code> value to the client,
     * with no carriage return-line feed (CRLF) at the end.
     * @param f			the <code>float</code> value
     *				to send to the client
     * @exception IOException	if an input or output exception occurred
     */
    //写float
    public void print(float f) throws IOException {
    	print(String.valueOf(f));
    }
    /**
     * Writes a <code>double</code> value to the client,
     * with no carriage return-line feed (CRLF) at the end.
     * @param d			the <code>double</code> value
     *				to send to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //写double
    public void print(double d) throws IOException {
    	print(String.valueOf(d));
    }
    /**
     * Writes a carriage return-line feed (CRLF)
     * to the client.
     * @exception IOException 	if an input or output exception occurred
     */
    //换行
    public void println() throws IOException {
    	print("\r\n");
    }
    /**
     * Writes a <code>String</code> to the client,
     * followed by a carriage return-line feed (CRLF).
     * @param s			the <code>String</code> to write to the client
     * @exception IOException 	if an input or output exception occurred
     */
   //写string并回车
    public void println(String s) throws IOException {
    	print(s);
    	println();
    }
    /**
     * Writes a <code>boolean</code> value to the client,
     * followed by a
     * carriage return-line feed (CRLF).
     * @param b			the <code>boolean</code> value
     *				to write to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //boolean 回车
    public void println(boolean b) throws IOException {
    	print(b);
    	println();
    }
    /**
     * Writes a character to the client, followed by a carriage
     * return-line feed (CRLF).
     * @param c			the character to write to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //字符 回车
    public void println(char c) throws IOException {
    	print(c);
    	println();
    }
    /**
     * Writes an int to the client, followed by a
     * carriage return-line feed (CRLF) character.
     * @param i			the int to write to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //int 回车
    public void println(int i) throws IOException {
    	print(i);
    	println();
    }
    /**
     * Writes a <code>long</code> value to the client, followed by a
     * carriage return-line feed (CRLF).
     * @param l			the <code>long</code> value to write to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //long 回车
    public void println(long l) throws IOException {
    	print(l);
    	println();
    }
    /**
     * Writes a <code>float</code> value to the client,
     * followed by a carriage return-line feed (CRLF).
     * @param f			the <code>float</code> value to write to the client
     * @exception IOException 	if an input or output exception 			occurred
     */
    //float 回车
    public void println(float f) throws IOException {
    	print(f);
    	println();
    }
    /**
     * Writes a <code>double</code> value to the client,
     * followed by a carriage return-line feed (CRLF).
     * @param d			the <code>double</code> value	to write to the client
     * @exception IOException 	if an input or output exception occurred
     */
    //double 回车
    public void println(double d) throws IOException {
    	print(d);
    	println();
    }
}