JSPWriter and PrintWriter objects in JSP 

• JSP pages have access to the out object. This allows your jsp code (and bean code) to write directly to the browser page,  eliminating the need for expression tags <%=  %>. 
• Using the out object makes your code more readable and saves development time.
• out is an instance of  the javax.servlet.jsp.JspWriter class and provides the same print and println functions that a PrintWriter has.
• There are differences though,  
• JspWriters (unlike PrintWriters) will throw IOExceptions.
• JspWriters perform buffering, that is, your prints and printlns are buffered on the server  and sent in blocks to the client stations.
• out is setup to do the block sending (flushing of buffers) automatically.  You can turn this off and control when the blocks are sent to the client yourself.
• Example: Write the numbers from 1 to 100, one per line, to the browser (<br> is the html line break tag)

<%
      //
      // example using expression tags
      //
      for(int i = 1; i <= 100; i++)
      {
%>
       <%= i+""> <br>
<%  } %>


<%
      //
      // example using the out object
      //
      for(int i = 1; i <= 100; i++)
      {
         out.println(i+"<br>");
       }
%>

• Some standard Java functions require the use of PrintWriters.  If you want to use these functions you can create a PrintWriter object based on the out object.

 java.io.PrintWriter pw = new java.io.PrintWriter(out);