Servlet 链提供了Servlet 应用的一种特殊功能。与UNIX 和DOS 命令中的管道类似，可以将多个Servlet 以特定顺序链接起来。在Servlet 链中，一个Servlet 的输出被当作下一个Servlet 的输入，而链中最后一个Servlet 的输出被返回到浏览器。
编程思路：首先编写一个表过滤器Servlet，它的作用主要是按照一定的表格格式输出，在通过Servlet 表过滤器(TableFilter.java)后，无格式化的Servlet(ghq.java)所有的行将会被格式化成HTML表格。
表过滤器 TableFilter.java 的源代码如下：(代码节选)
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
public class TableFilter extends HttpServlet
{
public void service(HttpServletRequest req, HttpServletResponse resp)
throws ServletException, java.io.IOException
{
// Get all headers set by the previous servlet and echo them
java.util.Enumeration e = req.getHeaderNames();
while (e.hasMoreElements()) {
String header = (String)e.nextElement();
String value = req.getHeader(header);
resp.setHeader(header, value);
}
// Get the input and output streams
ServletInputStream in = req.getInputStream();
ServletOutputStream out = resp.getOutputStream();
// Only process if this is a recognized MIME type
String type = req.getContentType();
if (type.equals("text/html") || type.equals("text/table") ||
type.equals("application/x-www-form-urlencoded")) {
resp.setContentType("text/html");
// Create a buffered reader that we can use to read
// a single line at a time
BufferedReader br = new BufferedReader(new InputStreamReader(in));
boolean inTable = false;
int tableCols = 0;
boolean headerRow = false;
// Read until no more data exists
while (true) {
String s = br.readLine();
// null indicates end of file
if (s == null) {
break;
}
// If we are in the middle of a table command, process
// the line
if (inTable) {
// Search for the end of the table
if (s.startsWith("");
// Output the table
out.println("姓名,性别,联系电话");
out.println("谷物,男,4324552");
out.println("江淮,女,2345265");
out.println("王冠,男,7867655");
out.println("张罗,男,5654343");
out.println("许愿,女,8876554");
out.println("");
// Wrap up
out.println(" |
