環境：Tomcat 5.5.7 + J2SE 5.0 + PostgreSQL 8.0
我將分幾個步驟完成對一個新聞發布系統的構建，來理解JSP的一些基本使用方法！
首先我將先介紹這個新聞發布系統的基本結構：
index.jsp：管理員登陸界面
check.jsp：驗證管理員身份
main.jsp：管理員添加新聞的頁面
pub.jsp：發布信息的頁面
display：顯示所有的新聞
而後台的程序主要有：
DB.java：數據庫連接
MD5.java：MD5算法
PubBean.java：發布
CheckBean.java：核實登陸身份
即當你從index -> main -> display 走一趟你基本就可以完成一個新聞發布系統的基本功能了！
我並非把新聞的標題和內容都寫入數據庫，因為那樣太耗費數據庫系統的資源，而且在訪問的時候總要讀取數
據庫，很費勁，我把新聞寫入了一個單獨的HTM文件，之後把標題及HTM文件的名字寫入的數據庫！
而這個HTM文件的名字怎麼隨機生成呢？我選擇了MD5算法，因為每個新聞的標題都不會相同，所以保證了唯一
性！
下面我先把這個系統的基本框架勾勒出來，說的大一點，這似乎就是這個“系統”的“內核”啦！:)
================數據庫部分==================
CREATE TABLE administrator
(
admin char(16),
"password" char(32)
)
WITHOUT OIDS;
ALTER TABLE administrator OWNER TO admin;
CREATE TABLE news
(
title char(255),
page char(255)
)
WITHOUT OIDS;
ALTER TABLE news OWNER TO admin;
================程序部分==================
package login;
import java.sql.*;
public class DB {
private Connection conn;
private Statement stmt;
private ResultSet rs;
public DB() {
try {
Class.forName("org.postgresql.Driver");
conn = DriverManager.getConnection
("jdbc:postgresql://localhost:5432/news?user=admin&&password=");
stmt = conn.createStatement();
}
catch(Exception e) {
System.out.println(e);
}
}
public void update(String sql) {
try {
stmt.executeUpdate(sql);
}
catch(Exception e) {
System.out.println(e);
}
}
public ResultSet quarry(String sql) {
try {
rs = stmt.executeQuery(sql);
}
catch(Exception e) {
System.out.println(e);
}
return rs;
}
}
package login;
import java.sql.*;
import java.io.*;
public class PubBean {
private String title,context;
private DB db;
private MD5 md5;
public PubBean() {
db = new DB();
md5 = new MD5();
}
public void setTitle(String title){
this.title = title;
}
public void setContext(String context) {
this.context = context;
}
public void pubIt() {
try {
title = new String(title.getBytes("8859_1"),"gb2312");
context = new String(context.getBytes("8859_1"),"gb2312");
String titleMD5 = md5.getkeyBeanofStr(title);
db.update("insert into news values('"+title+"','"+titleMD5+"')");
String file = "newsice"+titleMD5+".htm";
PrintWriter pw = new PrintWriter(new FileOutputStream(file));
pw.println("<title>"+title+"</title>");
pw.println(context);
pw.close();
}
catch(Exception e){
System.out.println(e);
}
}
}
package login;
import java.sql.*;
public class CheckBean {
private String message="",admin,password;
private DB db;
public CheckBean() {
db = new DB();
}
public void setAdmin(String admin){
this.admin = admin;
}
public void setPassword(String password) {
this.password = password;
}
public String checkIt() {
try {
ResultSet rs = db.quarry("select * from administrator where
admin='"+this.admin+"'");
while(rs.next()){
String pws = rs.getString("password").trim();
if(pws.equals(this.password)){
message = "密碼正確！";
}
else message = "密碼錯誤！";
return message;
}
message = "用戶不存在！";
}
catch(Exception e) {
System.out.println(e);
}
return message;
}
}
================頁面部分==================
index.jsp:
<%@ page contentType="text/html;charset=gb2312"%>
<html><head><title>登陸系統</title></head>
<body>
<form name="login" action="check.jsp" method="post">
用戶：<input type="text" name="admin"><br>
密碼：<input type="password" name="password"><br>
<input type="submit" value="登陸"><br>
</form>
</body>
</html>
<%
String error=request.getParameter("error");
error=new String(error.getBytes("8859_1"),"gb2312");
if(error==null) {}
else{
%>
<%=error%>
<%
}
%>
check.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="login.CheckBean"%>
<%
String admin = request.getParameter("admin");
String password = request.getParameter("password");
%>
<jsp:useBean id="checkBean" class="login.CheckBean"/>
<jsp:setProperty name="checkBean" property="admin" value="<%= admin.trim() %>"/>
<jsp:setProperty name="checkBean" property="password" value="<%= password.trim() %>"/>
<%
String result = checkBean.checkIt();
if(result.equals("密碼正確！")){
session.setAttribute("admin",admin);
response.sendRedirect("main.jsp");
}
else
{
%>
<jsp:forward page="index.jsp">
<jsp:param name="error" value="<%=result%>"/>
</jsp:forward>
<%
}
%>
main.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<%
String admin =(String)(session.getAttribute("admin"));
if(admin==null){
response.sendRedirect("index.jsp");
}
else{
%>
<html><head><title>新聞發布</title></head>
<body>
<form name="pub" action="pub.jsp" method="post">
題目：<input type="text" name="title"><br>
內容：<textarea cols="100" rows="10" name="context"></textarea><br>
<input type="submit" value="提交"><br>
</form>
</body>
</html>
<%}%>
pub.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<%
String admin = (String)(session.getAttribute("admin"));
String title = request.getParameter("title");
String context = request.getParameter("context");
if(admin == null){
response.sendRedirect("index.jsp");
}
else{
%>
<jsp:useBean id="pubBean" class="login.PubBean"/>
<jsp:setProperty name="pubBean" property="title" value="<%= title.trim() %>"/>
<jsp:setProperty name="pubBean" property="context" value="<%= context %>"/>
<%
pubBean.pubIt();
response.sendRedirect("display.jsp");
}
%>
display.jsp
<%@ page contentType="text/html;charset=gb2312"%>
<%@ page import="java.sql.*"%>
<%
Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
Connection conn=DriverManager.getConnection("jdbc:odbc:PostgreSQL","","");
Statement stmt=conn.createStatement();
%>
<html><head><title>新聞</title></head>
<body>
<%
ResultSet rs=stmt.executeQuery("SELECT * FROM news");
//顯示記錄
while(rs.next()){
out.print("<a href=news/ice"+rs.getString(2)+".htm target=_blank>"+rs.getString
(1)+"</a>");
out.println("<br>");
} %>
</body>
</html>
好了，基本的東西都實現了，希望現在已經可以給你一個完整的面貌了，在後面的文章中，我再把程序一步步
的完善，增加一些新的功能！
下面的是md5的算法在網上找的，轉載一下：
package login;
import java.lang.reflect.*;
public class MD5 {
/* 下面這些S11-S44實際上是一個4*4的矩陣，在原始的C實現中是用#define 實現的，
這裡把它們實現成為static final是表示了只讀，切能在同一個進程空間內的多個
Instance間共享*/
static final int S11 = 7;
static final int S12 = 12;
static final int S13 = 17;
static final int S14 = 22;
static final int S21 = 5;
static final int S22 = 9;
static final int S23 = 14;
static final int S24 = 20;
static final int S31 = 4;
static final int S32 = 11;
static final int S33 = 16;
static final int S34 = 23;
static final int S41 = 6;
static final int S42 = 10;
static final int S43 = 15;
static final int S44 = 21;
static final byte[] PADDING = { -128, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
/* 下面的三個成員是keyBean計算過程中用到的3個核心數據，在原始的C實現中
被定義到keyBean_CTX結構中
*/
private long[] state = new long[4]; // state (ABCD)
private long[] count = new long[2]; // number of bits, modulo 2^64 (lsb first)
private byte[] buffer = new byte[64]; // input buffer
/* digestHexStr是keyBean的唯一一個公共成員，是最新一次計算結果的
16進制ASCII表示.
*/
public String digestHexStr;
/* digest,是最新一次計算結果的2進制內部表示，表示128bit的keyBean值.
*/
private byte[] digest = new byte[16];
/*
getkeyBeanofStr是類keyBean最主要的公共方法，入口參數是你想要進行keyBean變換的字符串
返回的是變換完的結果，這個結果是從公共成員digestHexStr取得的．
*/
public String getkeyBeanofStr(String inbuf) {
keyBeanInit();
keyBeanUpdate(inbuf.getBytes(), inbuf.length());
keyBeanFinal();
digestHexStr = "";
for (int i = 0; i < 16; i++) {
digestHexStr += byteHEX(digest[i]);
}
return digestHexStr;
}
// 這是keyBean這個類的標准構造函數，JavaBean要求有一個public的並且沒有參數的構造函數
public MD5() {
keyBeanInit();
return;
}
/* keyBeanInit是一個初始化函數，初始化核心變量，裝入標准的幻數 */
private void keyBeanInit() {
count[0] = 0L;
count[1] = 0L;
///* Load magic initialization constants.
state[0] = 0x67452301L;
state[1] = 0xefcdab89L;
state[2] = 0x98badcfeL;
state[3] = 0x10325476L;
return;
}
/* F, G, H ,I 是4個基本的keyBean函數，在原始的keyBean的C實現中，由於它們是
簡單的位運算，可能出於效率的考慮把它們實現成了宏，在java中，我們把它們
實現成了private方法，名字保持了原來C中的。 */
private long F(long x, long y, long z) {
return (x & y) | ((~x) & z);
}
private long G(long x, long y, long z) {
return (x & z) | (y & (~z));
}
private long H(long x, long y, long z) {
return x ^ y ^ z;
}
private long I(long x, long y, long z) {
return y ^ (x | (~z));
}
/*
FF,GG,HH和II將調用F,G,H,I進行近一步變換
FF, GG, HH, and II transformations for rounds 1, 2, 3, and 4.
Rotation is separate from addition to prevent recomputation.
*/
private long FF(long a, long b, long c, long d, long x, long s,
long ac) {
a += F (b, c, d) + x + ac;
a = ((int) a << s) | ((int) a >>> (32 - s));
a += b;
return a;
}
private long GG(long a, long b, long c, long d, long x, long s,
long ac) {
a += G (b, c, d) + x + ac;
a = ((int) a << s) | ((int) a >>> (32 - s));
a += b;
return a;
}
private long HH(long a, long b, long c, long d, long x, long s,
long ac) {
a += H (b, c, d) + x + ac;
a = ((int) a << s) | ((int) a >>> (32 - s));
a += b;
return a;
}
private long II(long a, long b, long c, long d, long x, long s,
long ac) {
a += I (b, c, d) + x + ac;
a = ((int) a << s) | ((int) a >>> (32 - s));
a += b;
return a;
}
/*
keyBeanUpdate是keyBean的主計算過程，inbuf是要變換的字節串，inputlen是長度，這個
函數由getkeyBeanofStr調用，調用之前需要調用keyBeaninit，因此把它設計成private的
*/
private void keyBeanUpdate(byte[] inbuf, int inputLen) {
int i, index, partLen;
byte[] block = new byte[64];
index = (int)(count[0] >>> 3) & 0x3F;
// /* Update number of bits */
if ((count[0] += (inputLen << 3)) < (inputLen << 3))
count[1]++;
count[1] += (inputLen >>> 29);
partLen = 64 - index;
// Transform as many times as possible.
if (inputLen >= partLen) {
keyBeanMemcpy(buffer, inbuf, index, 0, partLen);
keyBeanTransform(buffer);
for (i = partLen; i + 63 < inputLen; i += 64) {
keyBeanMemcpy(block, inbuf, 0, i, 64);
keyBeanTransform (block);
}
index = 0;
} else
i = 0;
///* Buffer remaining input */
keyBeanMemcpy(buffer, inbuf, index, i, inputLen - i);
}
/*
keyBeanFinal整理和填寫輸出結果
*/
private void keyBeanFinal () {
byte[] bits = new byte[8];
int index, padLen;
///* Save number of bits */
Encode (bits, count, 8);
///* Pad out to 56 mod 64.
index = (int)(count[0] >>> 3) & 0x3f;
padLen = (index < 56) ? (56 - index) : (120 - index);
keyBeanUpdate (PADDING, padLen);
///* Append length (before padding) */
keyBeanUpdate(bits, 8);
///* Store state in digest */
Encode (digest, state, 16);
}
/* keyBeanMemcpy是一個內部使用的byte數組的塊拷貝函數，從input的inpos開始把len長度的
字節拷貝到output的outpos位置開始
*/
private void keyBeanMemcpy (byte[] output, byte[] input,
int outpos, int inpos, int len)
{
int i;
for (i = 0; i < len; i++)
output[outpos + i] = input[inpos + i];
}
/*
keyBeanTransform是keyBean核心變換程序，有keyBeanUpdate調用，block是分塊的原始字節
*/
private void keyBeanTransform (byte block[]) {
long a = state[0], b = state[1], c = state[2], d = state[3];
long[] x = new long[16];
Decode (x, block, 64);
/* Round 1 */
a = FF (a, b, c, d, x[0], S11, 0xd76aa478L); /* 1 */
d = FF (d, a, b, c, x[1], S12, 0xe8c7b756L); /* 2 */
c = FF (c, d, a, b, x[2], S13, 0x242070dbL); /* 3 */
b = FF (b, c, d, a, x[3], S14, 0xc1bdceeeL); /* 4 */
a = FF (a, b, c, d, x[4], S11, 0xf57c0fafL); /* 5 */
d = FF (d, a, b, c, x[5], S12, 0x4787c62aL); /* 6 */
c = FF (c, d, a, b, x[6], S13, 0xa8304613L); /* 7 */
b = FF (b, c, d, a, x[7], S14, 0xfd469501L); /* 8 */
a = FF (a, b, c, d, x[8], S11, 0x698098d8L); /* 9 */
d = FF (d, a, b, c, x[9], S12, 0x8b44f7afL); /* 10 */
c = FF (c, d, a, b, x[10], S13, 0xffff5bb1L); /* 11 */
b = FF (b, c, d, a, x[11], S14, 0x895cd7beL); /* 12 */
a = FF (a, b, c, d, x[12], S11, 0x6b901122L); /* 13 */
d = FF (d, a, b, c, x[13], S12, 0xfd987193L); /* 14 */
c = FF (c, d, a, b, x[14], S13, 0xa679438eL); /* 15 */
b = FF (b, c, d, a, x[15], S14, 0x49b40821L); /* 16 */
/* Round 2 */
a = GG (a, b, c, d, x[1], S21, 0xf61e2562L); /* 17 */
d = GG (d, a, b, c, x[6], S22, 0xc040b340L); /* 18 */
c = GG (c, d, a, b, x[11], S23, 0x265e5a51L); /* 19 */
b = GG (b, c, d, a, x[0], S24, 0xe9b6c7aaL); /* 20 */
a = GG (a, b, c, d, x[5], S21, 0xd62f105dL); /* 21 */
d = GG (d, a, b, c, x[10], S22, 0x2441453L); /* 22 */
c = GG (c, d, a, b, x[15], S23, 0xd8a1e681L); /* 23 */
b = GG (b, c, d, a, x[4], S24, 0xe7d3fbc8L); /* 24 */
a = GG (a, b, c, d, x[9], S21, 0x21e1cde6L); /* 25 */
d = GG (d, a, b, c, x[14], S22, 0xc33707d6L); /* 26 */
c = GG (c, d, a, b, x[3], S23, 0xf4d50d87L); /* 27 */
b = GG (b, c, d, a, x[8], S24, 0x455a14edL); /* 28 */
a = GG (a, b, c, d, x[13], S21, 0xa9e3e905L); /* 29 */
d = GG (d, a, b, c, x[2], S22, 0xfcefa3f8L); /* 30 */
c = GG (c, d, a, b, x[7], S23, 0x676f02d9L); /* 31 */
b = GG (b, c, d, a, x[12], S24, 0x8d2a4c8aL); /* 32 */
/* Round 3 */
a = HH (a, b, c, d, x[5], S31, 0xfffa3942L); /* 33 */
d = HH (d, a, b, c, x[8], S32, 0x8771f681L); /* 34 */
c = HH (c, d, a, b, x[11], S33, 0x6d9d6122L); /* 35 */
b = HH (b, c, d, a, x[14], S34, 0xfde5380cL); /* 36 */
a = HH (a, b, c, d, x[1], S31, 0xa4beea44L); /* 37 */
d = HH (d, a, b, c, x[4], S32, 0x4bdecfa9L); /* 38 */
c = HH (c, d, a, b, x[7], S33, 0xf6bb4b60L); /* 39 */
b = HH (b, c, d, a, x[10], S34, 0xbebfbc70L); /* 40 */
a = HH (a, b, c, d, x[13], S31, 0x289b7ec6L); /* 41 */
d = HH (d, a, b, c, x[0], S32, 0xeaa127faL); /* 42 */
c = HH (c, d, a, b, x[3], S33, 0xd4ef3085L); /* 43 */
b = HH (b, c, d, a, x[6], S34, 0x4881d05L); /* 44 */
a = HH (a, b, c, d, x[9], S31, 0xd9d4d039L); /* 45 */
d = HH (d, a, b, c, x[12], S32, 0xe6db99e5L); /* 46 */
c = HH (c, d, a, b, x[15], S33, 0x1fa27cf8L); /* 47 */
b = HH (b, c, d, a, x[2], S34, 0xc4ac5665L); /* 48 */
/* Round 4 */
a = II (a, b, c, d, x[0], S41, 0xf4292244L); /* 49 */
d = II (d, a, b, c, x[7], S42, 0x432aff97L); /* 50 */
c = II (c, d, a, b, x[14], S43, 0xab9423a7L); /* 51 */
b = II (b, c, d, a, x[5], S44, 0xfc93a039L); /* 52 */
a = II (a, b, c, d, x[12], S41, 0x655b59c3L); /* 53 */
d = II (d, a, b, c, x[3], S42, 0x8f0ccc92L); /* 54 */
c = II (c, d, a, b, x[10], S43, 0xffeff47dL); /* 55 */
b = II (b, c, d, a, x[1], S44, 0x85845dd1L); /* 56 */
a = II (a, b, c, d, x[8], S41, 0x6fa87e4fL); /* 57 */
d = II (d, a, b, c, x[15], S42, 0xfe2ce6e0L); /* 58 */
c = II (c, d, a, b, x[6], S43, 0xa3014314L); /* 59 */
b = II (b, c, d, a, x[13], S44, 0x4e0811a1L); /* 60 */
a = II (a, b, c, d, x[4], S41, 0xf7537e82L); /* 61 */
d = II (d, a, b, c, x[11], S42, 0xbd3af235L); /* 62 */
c = II (c, d, a, b, x[2], S43, 0x2ad7d2bbL); /* 63 */
b = II (b, c, d, a, x[9], S44, 0xeb86d391L); /* 64 */
state[0] += a;
state[1] += b;
state[2] += c;
state[3] += d;
}
/*Encode把long數組按順序拆成byte數組，因為java的long類型是64bit的，
只拆低32bit，以適應原始C實現的用途
*/
private void Encode (byte[] output, long[] input, int len) {
int i, j;
for (i = 0, j = 0; j < len; i++, j += 4) {
output[j] = (byte)(input[i] & 0xffL);
output[j + 1] = (byte)((input[i] >>> 8) & 0xffL);
output[j + 2] = (byte)((input[i] >>> 16) & 0xffL);
output[j + 3] = (byte)((input[i] >>> 24) & 0xffL);
}
}
/*Decode把byte數組按順序合成成long數組，因為java的long類型是64bit的，
只合成低32bit，高32bit清零，以適應原始C實現的用途
*/
private void Decode (long[] output, byte[] input, int len) {
int i, j;
for (i = 0, j = 0; j < len; i++, j += 4)
output[i] = b2iu(input[j]) |
(b2iu(input[j + 1]) << 8) |
(b2iu(input[j + 2]) << 16) |
(b2iu(input[j + 3]) << 24);
return;
}
/*
b2iu是我寫的一個把byte按照不考慮正負號的原則的＂升位＂程序，因為java沒有unsigned運算
*/
public static long b2iu(byte b) {
return b < 0 ? b & 0x7F + 128 : b;
}
/*byteHEX()，用來把一個byte類型的數轉換成十六進制的ASCII表示，
因為java中的byte的toString無法實現這一點，我們又沒有C語言中的
sprintf(outbuf,"%02X",ib)
*/
public static String byteHEX(byte ib) {
char[] Digit = { '0','1','2','3','4','5','6','7','8','9',
'A','B','C','D','E','F' };
char [] ob = new char[2];
ob[0] = Digit[(ib >>> 4) & 0X0F];
ob[1] = Digit[ib & 0X0F];
String s = new String(ob);
return s;
}
/*
public static void main(String args[]) {
MD5 m = new MD5();
System.out.println("我愛你："+m.getkeyBeanofStr("我愛你"));
}
*/
}
