htmlfiltertag.java

JavaWeb高级特性书中源代码

package org.it315;
import java.io.IOException;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.BodyTagSupport;
public class HtmlFilterTag extends BodyTagSupport 
{
	public int doEndTag() throws JspException 
	{
		if(bodyContent != null)
		{
			String content = bodyContent.getString();
			content = filter(content);//调用filter方法对HTML标签进行转义
			try
			{
				//pageContext.getOut().write(content);
				bodyContent.getEnclosingWriter().write(content);
			} 
			catch (IOException e)
			{
				e.printStackTrace();
			}
		}
		return EVAL_PAGE;
	}
	public String filter(String message)
	{
        if (message == null)
            return (null);

        char content[] = new char[message.length()];
        message.getChars(0, message.length(), content, 0);
        StringBuffer result = new StringBuffer(content.length + 50);
        for (int i=0; i<content.length; i++) {
            switch (content[i]) {
            case '<':
                result.append("&lt;");
                break;
            case '>':
                result.append("&gt;");
                break;
            case '&':
                result.append("&amp;");
                break;
            case '"':
                result.append("&quot;");
                break;
            default:
                result.append(content[i]);
            }
        }
        return (result.toString());
	}
}