http://www.Linuxforum.net 作者 dream_bird@163.net
这几天整理我机器中的旧文档时，发现了一个不错的基于Java servlet技术的留言簿，好象是几个月前我从 http://go.163.com/~netjava/ 找到的，后台数据库用的是SQL Server。现在我的Redhat 6.1上正好安装了Apache Jserv 1.1、GNUjsp 1.0、mysql（包括mm.mysql的JDBC驱动），除此之外还有Tomcat 3.1和Cocoon 1.8。当然，一般只运行Jserv + GNUJSP + Cocoon + MySQL，Tomcat是不运行的。既然环境是现成的，为什么不把这个留言簿改改让它可以运行呢？
首先改造它的源代码，把JDBC 驱动和URL改成MySQL的。GuestBookServlet.java程序代码如下：
//javac -encoding iso8859_1 GuestBookServlet.java ( for Chinese gb2312 )
//javac GuestBookServlet.java
import javax.servlet.*;
import javax.servlet.http.*;
import java.io.*;
import java.net.*;
import java.sql.*;
import java.text.DateFormat;
import java.util.Locale;
public class GuestBookServlet extends HttpServlet {
public void init(ServletConfig conf) throws ServletException {
super.init(conf);
try {
Class.forName("org.gjt.mm.mysql.Driver");
}
catch( Exception e ) {
}
}
//Sign guestbook
public void doPost(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
String url = "jdbc:mysql://localhost.localdomain:3306/GuestBook?user=guest&passWord=password";
ServletOutputStream out = res.getOutputStream();
java.util.Date date = new java.util.Date();
String name, email, comment;
Connection conn = null;
Exception err = null;
int id = -1;
String[] tmp;
//init
//accept name
tmp = req.getParameterValues("name");
if( tmp == null tmp.length != 1 ) {
name = null;
}
else {
name = tmp[0];
}
//accept email
tmp = req.getParameterValues("email");
if( tmp == null tmp.length != 1 ) {
email = null;
}
else {
email = tmp[0];
}
//accept comments
tmp = req.getParameterValues("comments");
if( tmp == null tmp.length != 1 ) {
comment = null;
}
else {
comment = tmp[0];
}
//header
res.setContentType("text/Html");
printPageHeader(out);
if( name.length() < 1 ) {
out.println("You must specify a valid name!");
printCommentForm(out);
printPageFooter(out);
return;
}
if( email.length() < 3 ) {
out.println("You must specify a valid email address!");
printCommentForm(out);
printPageFooter(out);
return;
}
if( email.indexOf("@") < 1 ) {
out.println("You must specify a valid email address!");
printCommentForm(out);
printPageFooter(out);
return;
}
if( comment.length() < 1 ) {
out.println("You left no comments!");
printCommentForm(out);
printPageFooter(out);
return;
}
//Access to MySQL
try {
Statement statement;
ResultSet result;
conn = DriverManager.getConnection(url);
statement = conn.createStatement();
result = statement.executeQuery("SELECT next_id " +
"FROM sys_gen " +
"WHERE id = ´comment_id´");
if( !result.next() ) {
throw new java.sql.SQLException("Failed to generate id.");
}
id = result.getInt(1) + 1;
result.close();
statement.close();
statement = conn.createStatement();
statement.executeUpdate("UPDATE sys_gen SET next_id = " + id +
" WHERE id = ´comment_id´");
statement.close();
statement = conn.createStatement();
comment = fixComment(comment);
statement.executeUpdate("INSERT into comments " +
"(comment_id, email, name, comment, " +
"cmt_date) "+
"VALUES (" + id +", ´" + email +
"´, ´" + name + "´, ´" +
comment + "´, ´" + date.getTime() +
"´)");
statement.close();
}
catch( java.sql.SQLException e ) {
e.printStackTrace();
err = e;
}
finally {
if( conn != null ) {
try { conn.close(); }
catch( Exception e ) { }
}
}
if( err != null ) {
out.println("An error occurred on save: " + err.getMessage());
}
else {
printCommentForm(out);
printComments(out);
}
}
//browser the guestbook
public void doGet(HttpServletRequest req, HttpServletResponse res)
throws ServletException, IOException {
String url = "jdbc:mysql://localhost.localdomain:3306/GusetBook?user=guest&password=password";
ServletOutputStream out = res.getOutputStream();
Connection conn = null;
int id = -1;
Exception err = null;
res.setContentType("text/html");
printPageHeader(out);
printCommentForm(out);
printComments(out);
printPageFooter(out);
}
public String getServletInfo() {
return "Guest Book Servlet v1.0
Copyright 251 2000 meng_bo";
}
private void printCommentForm(ServletOutputStream out)
throws IOException {
out.println("
");
out.println("");
out.println("");
out.println("");
out.println(" Name: ");
out.println(" ");
out.println(" ");
out.println("
");
out.println("");
out.println(" Email: ");
out.println(" ");
out.println("
");
out.println("");
out.println(" Comments: ");
out.println("
");
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
out.println(" ");
out.println("");
out.println("
");
}
private void printComments(ServletOutputStream out)
throws IOException {
Connection conn = null;
try {
DateFormat fmt = DateFormat.getDateInstance(DateFormat.FULL,
Locale.getDefault());
String url = "jdbc:mysql://localhost.localdomain:3306/GuestBook?user=guest&password=password";
Statement stmt;
ResultSet results;
conn = DriverManager.getConnection(url);
stmt = conn.createStatement();
results = stmt.executeQuery("SELECT name, email, cmt_date, " +
"comment, comment_id " +
"FROM comments " +
"ORDER BY cmt_date");
out.println("
");
while( results.next() ) {
String name, email, cmt;
java.util.Date date;
name = results.getString(1);
if( results.wasNull() ) {
name = "Unknown User";
}
email = results.getString(2);
if( results.wasNull() ) {
email = "user@host";
}
date = results.getDate(3);
if( results.wasNull() ) {
date = new java.util.Date();
}
cmt = results.getString(4);
if( results.wasNull() ) {
cmt = "No comment.";
}
out.println("
" + name + " (" + email + ") on " +
fmt.format(date));
cmt = noHTML(cmt);
out.println("
" + cmt + "
");
}
out.println("
");
}
catch( SQLException e ) {
out.println("A database error occurred: " + e.getMessage());
}
if( conn != null ) {
try { conn.close(); }
catch( Exception e ) { }
}
}
private void printPageHeader(ServletOutputStream out)
throws IOException {
out.println("");
out.println("");
out.println("");
out.println("");
out.println("");
out.println("
Guest Book
");
}
private void printPageFooter(ServletOutputStream out)
throws IOException {
out.println("");
out.println("");
out.flush();
}
private String noHTML(String cmt) {
if( cmt.indexOf("<") != -1 cmt.indexOf(">") != -1 ) {
String tmp = "";
for(int i=0; i char c = cmt.charAt(i);
if( c == ´<´ ) {
tmp = tmp + "<";
}
else if( c == ´>´ ) {
tmp = tmp + ">";
}
else {
tmp = tmp + c;
}
}
cmt = tmp;
}
return cmt;
}
private String fixComment(String comment) {
if( comment.indexOf("´") != -1 ) {
String tmp = "";
for(int i=0; i char c = comment.charAt(i);
if( c == ´´´ ) {
tmp = tmp + "\´";
}
else {
tmp = tmp + c;
}
}
comment = tmp;
}
return comment;
}
}
对于该程序所要使用的数据库和表，我写了如下三个脚本：
1. create_database.sql
create database GuestBook;
grant select,insert,update,delete,create,drop
on GuestBook.*
to guest@localhost.localdomain
identified by ´password´;
2. create_tables.sql
use GuestBook;
create table sys_gen(
next_id int(8) not null,
id char(10) not null);
insert into sys_gen (next_id, id) values (0, ´comment_id´);
create table comments(
comment_id int(8) not null,
email varchar(64),
name varchar(32),
comment varchar(128),
cmt_date date default ´0000-00-00´ not null);
3. install.sh
#/bin/sh
mysql --user=root --host=localhost.localdomain --password=password < create_database.sql
mysql --user=guest --host=localhost.localdomain --password=password < create_tables.sql
有了这些代码，一切就再明白不过了吧。这里还需要注重的是“<”和“>”在HTML文件中会出问题，所以谁要把这篇文档转换成HTML文件时一定要注重。
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