BlogJava-learning java-随笔分类-java

corejava读书笔记

my java — Fri, 23 Jun 2006 05:25:00 GMT

第二章 Java编程环境
2.1安装java
1、java工具包http://java.sun.com/j2se/1.4/install-windows.html
2、设置执行环境（windows 2000)
PATH=c:\jdk\bin;
3、安装库源文件和文档
jar xvf src.jar
jar xvf j2sdkversion-doc.zip

第一个java例子
eg:Weclome.java

public class Welcome
{
public static void main(String[] args)
{
String[] greeting=new String[3];
greeting[0]="Welcome to Core Java";
greeting[1]="by Car Horstman";
greeting[2]="and Gary Cornell";
for ( int i=0;iSystem.out.println(greeting[i]);
}
}

my java 2006-06-23 13:25 发表评论

jspsmartupload使用技巧

my java — Fri, 23 Jun 2006 01:34:00 GMT

1、获得表单中文本框的数据：
mySmartUpload.getRequest().getParameter("applyusrname")
java.util.Enumeration e = mySmartUpload.getRequest().getParameterNames();

my java 2006-06-23 09:34 发表评论

Strings

my java — Mon, 05 Sep 2005 05:56:00 GMT

char charAt(int index)

returns the character at the specified location.
int compareTo(String other)

returns a negative value if the string comes before other in dictionary order, a positive value if the string comes after other in dictionary order, or 0 if the strings are equal.
boolean endsWith(String suffix)

returns true if the string ends with suffix.
boolean equals(Object other)

returns true if the string equals other.
boolean equalsIgnoreCase(String other)

returns true if the string equals other, except for upper/lowercase distinction.
int indexOf(String str)
int indexOf(String str, int fromIndex)

return the start of the first substring equal to str, starting at index 0 or at fromIndex.
int lastIndexOf(String str)
int lastIndexOf(String str, int fromIndex)

return the start of the last substring equal to str, starting at the end of the string or at fromIndex.
int length()

returns the length of the string.
String replace(char oldChar, char newChar)

returns a new string that is obtained by replacing all characters oldChar in the string with newChar.
boolean startsWith(String prefix)

returns true if the string begins with prefix.
String substring(int beginIndex)
String substring(int beginIndex, int endIndex)

return a new string consisting of all characters from beginIndex until the end of the string or until endIndex (exclusive).
String toLowerCase()

returns a new string containing all characters in the original string, with uppercase characters converted to lower case.
String toUpperCase()

returns a new string containing all characters in the original string, with lowercase characters converted to upper case.
String trim()

returns a new string by eliminating all leading and trailing spaces in the original string.

字符串与基本数据类型的转换间的转换必须使用JSP中的对象函数
Boolean.getBoolean(String)
Byte.parseByte(String)
Short.parseShort(String)
Integer.parseInt(String)
Long.parseLong(String)
Float.parseDouble(String)
Double.parseDouble(String)
String.valueOF(数据)

Array

static void arraycopy(Object from, int fromIndex, Object to, int toIndex, int count)

Parameters:	`from`	an array of any type (Chapter 5 explains why this is a parameter of type `Object`)
	`fromIndex`	the starting index from which to copy elements
	`to`	an array of the same type as `from`
	`toIndex`	the starting index to which to copy elements
	`count`	the number of elements to copy

copies elements from the first array to the second array.

`java.util.Arrays` 1.2

static void sort(Xxx[] a)

Parameters:

a

an array of type int, long, short, char, byte, boolean, float or double

sorts the array, using a tuned QuickSort algorithm.
static int binarySearch(Xxx[] a, Xxx v)

Parameters:

a

a sorted array of type int, long, short, char, byte, boolean, float or double

v

a value of the same type as the elements of a

uses the BinarySearch algorithm to search for the value v. If it is found, its index is returned. Otherwise, a negative value r is returned; -r - 1 is the spot at which v should be inserted to keep a sorted.
static void fill(Xxx[] a, Xxx v)

Parameters:

a

an array of type int, long, short, char, byte, boolean, float or double

v

a value of the same type as the elements of a

sets all elements of the array to v.
static boolean equals(Xxx[] a, Object other)

Parameters:

a

an array of type int, long, short, char, byte, boolean, float or double

other

an object

returns true if other is an array of the same type, if it has the same length, and if the elements in corresponding indexes match.

Parameters:	`a`	an array of type `int`, `long`, `short`, `char`, `byte`, `boolean`, `float` or `double`

Parameters:	`a`	a sorted array of type `int`, `long`, `short`, `char`, `byte`, `boolean`, `float` or `double`
	`v`	a value of the same type as the elements of `a`

Parameters:	`a`	an array of type `int`, `long`, `short`, `char`, `byte`, `boolean`, `float` or `double`
	`v`	a value of the same type as the elements of `a`

Parameters:	`a`	an array of type `int`, `long`, `short`, `char`, `byte`, `boolean`, `float` or `double`
	`other`	an object

eg:

int[] smallPrimes = {2, 3, 5, 7, 11, 13};
  int[] luckyNumbers = {1001, 1002, 1003, 1004, 1005, 1006, 1007};
  System.arraycopy(smallPrimes, 2, luckyNumbers, 3, 3);
  for (int i = 0; i < luckyNumbers.length; i++)
     System.out.println(i + ": " + luckyNumbers[i]);

my java 2005-09-05 13:56 发表评论

jaas link

my java — Thu, 25 Aug 2005 06:29:00 GMT

http://java.sun.com/j2se/1.4.2/docs/guide/security/jaas/JAASRefGuide.html

http://java.sun.com/j2se/1.4.2/docs/guide/security/jaas/JAASLMDevGuide.html

http://java.sun.com/j2se/1.4.2/docs/guide/security/jaas/JAASRefGuide.html

http://java.sun.com/j2se/1.4.1/docs/api/javax/security/auth/login/Configuration.html

my java 2005-08-25 14:29 发表评论

JDBC实例代码

my java — Wed, 24 Aug 2005 06:49:00 GMT

DBPhoneLookupReuse.java
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class DBPhoneLookupReuse extends HttpServlet {

private Connection con = null;

public void init() throws ServletException {
    try {
      // Load (and therefore register) the Sybase driver
      Class.forName("com.jnetdirect.jsql.JSQLDriver");
      con = DriverManager.getConnection(
        "jdbc:JSQLConnect://127.0.0.1/database=JAAS", "sa", "db_password");
    }
    catch (ClassNotFoundException e) {
      throw new UnavailableException("Couldn't load database driver");
    }
    catch (SQLException e) {
      throw new UnavailableException("Couldn't get db connection");
    }
}

public void doGet(HttpServletRequest req, HttpServletResponse res)
                               throws ServletException, IOException {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();

out.println("Phonebook");
out.println("");

HtmlSQLResult result =
new HtmlSQLResult("SELECT UserName,Password FROM Users", con);

// Display the resulting output
out.println("

Users:

");
out.println(result);
out.println("");
}

public void destroy() {
    // Clean up.
    try {
      if (con != null) con.close();
    }
    catch (SQLException ignored) { }
}
}

HtmlSQLResult.java
import java.sql.*;

public class HtmlSQLResult {
private String sql;
private Connection con;

public HtmlSQLResult(String sql, Connection con) {
this.sql = sql;
this.con = con;
}

public String toString() { // can be called at most once
StringBuffer out = new StringBuffer();

// Uncomment the following line to display the SQL command at start of table
// out.append("Results of SQL Statement: " + sql + "

\n");

try {
Statement stmt = con.createStatement();

      if (stmt.execute(sql)) {
        // There's a ResultSet to be had
        ResultSet rs = stmt.getResultSet();
        out.append("

\n");

ResultSetMetaData rsmd = rs.getMetaData();

        int numcols = rsmd.getColumnCount();

        // Title the table with the result set's column labels
        out.append("

");
for (int i = 1; i <= numcols; i++)
out.append("\n");

while(rs.next()) {
out.append("

"); // start a new row
          for(int i = 1; i <= numcols; i++) {
            out.append("\n");
        }

// End the table
out.append("

" + rsmd.getColumnLabel(i)); out.append("
"); // start a new data element Object obj = rs.getObject(i); if (obj != null) out.append(obj.toString()); else out.append(" "); } out.append("

\n");
      }
      else {
        // There's a count to be had
        out.append("Records Affected: " + stmt.getUpdateCount());
      }
    }
    catch (SQLException e) {
      out.append("

ERROR:

" + e.getMessage());
    }

    return out.toString();
}
}

my java 2005-08-24 14:49 发表评论

JCIFS NTLM

my java — Fri, 19 Aug 2005 03:06:00 GMT

1、NTLM can be done with JCIFS and without HTTP. Only a few lines of code are required in the code of your servlet:

InetAddress ip = InetAddress.getByName(”192.168.0.1.”); // ip address of your windows controller
UniAddress myDomain = new UniAddress(ip);
NtlmPasswordAuthentication auth = new NtlmPasswordAuthentication(”MYDOMAIN”, “mylogin”, “mypasword”);
SmbSession.logon(myDomain, auth);

If an exception is triggered, the controller didn’t like the login and the password

2、Http方式下web.xml中filter的配置:

http://java.sun.com/dtd/web-app_2_3.dtd">

WEB APP
WEB APP description

  ShowRequestHeaders
  coreservlets.ShowRequestHeaders

  ShowRequestHeaders
  /ShowRequestHeaders

    NtlmHttpFilter
    jcifs.http.NtlmHttpFilter

        jcifs.http.domainController
        192.168.10.1

NtlmHttpFilter
/*

my java 2005-08-19 11:06 发表评论

Date类型变量加减天数

my java — Thu, 18 Aug 2005 05:26:00 GMT

//import java.text.*;
//import java.util.*;

public static String addDate(String day,int x)
{
    SimpleDateFormat format=new SimpleDateFormat("yyyy/MM/dd");
    Date date = null;
    try
    {
      date = format.parse(day);
    }
    catch (ParseException ex)
    {
      ex.printStackTrace();
    }
    if (date==null) return "";
    Calendar cal=Calendar.getInstance();
    cal.setTime(date);
    cal.add(Calendar.DAY_OF_MONTH,x);
    date=cal.getTime();
    System.out.println("3 days after(or before) is "+format.format(date));
    cal=null;
    return format.format(date);
}

my java 2005-08-18 13:26 发表评论

package编译

my java — Wed, 17 Aug 2005 03:34:00 GMT

建目录coreservlets,将两个servlets放在这个目录中,在coreservlet的上级目录
运行:
javac coreservlets/HelloServlet3.java

package coreservlets;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

/** Simple servlet for testing the use of packages
* and utilities from the same package.
*

* Taken from Core Servlets and JavaServer Pages 2nd Edition
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2003 Marty Hall; may be freely used or adapted.
*/

public class HelloServlet3 extends HttpServlet {
public void doGet(HttpServletRequest request,
                    HttpServletResponse response)
      throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    String title = "Hello (3)";
    out.println(ServletUtilities.headWithTitle(title) +
                "\n" +
                "

" + title + "

\n" +
"");
}
}

package coreservlets;

import javax.servlet.*;
import javax.servlet.http.*;

/** Some simple timesavers. Note that most are static methods.
*

* Taken from Core Servlets and JavaServer Pages 2nd Edition
* from Prentice Hall and Sun Microsystems Press,
* http://www.coreservlets.com/.
* © 2003 Marty Hall; may be freely used or adapted.
*/

public class ServletUtilities {
public static final String DOCTYPE =
" "Transitional//EN\">";

public static String headWithTitle(String title) {
    return(DOCTYPE + "\n" +
           "\n" +
           "" + title + "\n");
}

/** Read a parameter with the specified name, convert it
   * to an int, and return it. Return the designated default
   * value if the parameter doesn't exist or if it is an
   * illegal integer format.
*/

public static int getIntParameter(HttpServletRequest request,
                                    String paramName,
                                    int defaultValue) {
    String paramString = request.getParameter(paramName);
    int paramValue;
    try {
      paramValue = Integer.parseInt(paramString);
    } catch(NumberFormatException nfe) { // null or bad format
      paramValue = defaultValue;
    }
    return(paramValue);
}

public static double getDoubleParameter
                                 (HttpServletRequest request,
                                  String paramName,
                                  double defaultValue) {
    String paramString = request.getParameter(paramName);
    double paramValue;
    try {
      paramValue = Double.parseDouble(paramString);
    } catch(NumberFormatException nfe) { // null or bad format
      paramValue = defaultValue;
    }
    return(paramValue);
}

/** Replaces characters that have special HTML meanings
* with their corresponding HTML character entities.
*/

// Note that Javadoc is not used for the more detailed
// documentation due to the difficulty of making the
// special chars readable in both plain text and HTML.
//
// Given a string, this method replaces all occurrences of
// '<' with '<', all occurrences of '>' with
// '>', and (to handle cases that occur inside attribute
// values), all occurrences of double quotes with
// '"' and all occurrences of '&' with '&'.
// Without such filtering, an arbitrary string
// could not safely be inserted in a Web page.

public static String filter(String input) {
    if (!hasSpecialChars(input)) {
      return(input);
    }
    StringBuffer filtered = new StringBuffer(input.length());
    char c;
    for(int i=0; i      c = input.charAt(i);
      switch(c) {
        case '<': filtered.append("<"); break;
        case '>': filtered.append(">"); break;
        case '"': filtered.append("""); break;
        case '&': filtered.append("&"); break;
        default: filtered.append(c);
      }
    }
    return(filtered.toString());
}

private static boolean hasSpecialChars(String input) {
    boolean flag = false;
    if ((input != null) && (input.length() > 0)) {
      char c;
      for(int i=0; i        c = input.charAt(i);
        switch(c) {
          case '<': flag = true; break;
          case '>': flag = true; break;
          case '"': flag = true; break;
          case '&': flag = true; break;
        }
      }
    }
    return(flag);
}
}

my java 2005-08-17 11:34 发表评论

java中定时器timer类的实现和源代码

my java — Tue, 26 Jul 2005 01:00:00 GMT

在Windows编程中可以调用SetTimer在指定窗口安装定时器(Timer)，定时器可以在指定的时间间隔周期性回调用户指定的方法，用来执行周期性的任务，如果想取消定时器，可以调用KillTimer取消。但是在java标准包里中并没有这种类。下面介绍的这个类包可以实现上述功能。

下面是接口，需要支持定时器功能的类要实现这个接口：

TimerClient.java

package com.ly.util;

/**
* TimerClient Interface
*
* @version 1.0, 8 October 1995
*
*/
public interface TimerClient
{
void timerEvent(int id);
}

下面是定时器的实现，包括三个类：TimerCtl,TimerTask,TimerTasks。其中TimerTask用来描述定时器信息。TimerTasks是一个TimerTask的列表，这样我们就可以同时在一个应用中安插多个定时器。TimerCtl是定时器控制类，是个线程，不停地检查TimerTasks中是否有TimerTask到期，要是有TimerTask到达指定的时间，则回调TimerTask指定的TimerClient的timerEvent接口。

TimerCtl.java

package com.ly.util;

import java.util.Vector;
import java.util.Enumeration;
//import com.borland.jb.util.Diagnostic;

/**
* Timer Component
*
* Note:
* - The successful operation of this timer requires clients to execute simple, short
*    code snippets when called back by the engine. Otherwise the queue's delivery
*    mechanism will be held up
*
* Further work:
* - When Thread.Interrupt is implemented we can switch from the busy wait model to
*    the calculated wait model. Without the interrupt the thread waits for the
*    calculated interval before waking up. This is a problem if another shorter
*    request arrives. For now we'll assume the minimum resolution of the timer is
*    100ms.
*
* @version 1.0, 2 October 1995
*
*/
public class TimerCtl
{
static TimerTasks timerTasks;

public TimerCtl() {
}

/*
* Start a timer running
*/
public static void startTimer(TimerClient client, int eventId, long delay, boolean repeat) {
    // create the timer if necessary
    if (timerTasks == null) {
      timerTasks = new TimerTasks();
      timerTasks.start();
    }

//Diagnostic.out.println("TIMER: startTimer"+eventId);

// add the new task to the queue
timerTasks.add(client, eventId, delay, repeat);
}

/*
* Stop a timer
*/
public static void stopTimer(TimerClient client, int eventId) {
    //Diagnostic.out.println("TIMER: stopTimer"+eventId);
    if(timerTasks != null)
        timerTasks.end(client, eventId);
}
}

class TimerTasks extends Thread
{
Vector tasks = new Vector();
boolean suspended = false;
boolean sleeping = false;

/**
   * Thread task runner
   */
public void run() {
    // Loop forever
    while (true) {
      long sleepTime = 0;

      // Ensure that the tasks class is protected
      synchronized (tasks) {
        //Diagnostic.out.println("TIMER: Tick");

        // Scan the job list for any jobs which may fire.
        // Mark one-shot jobs for deletion
        // Calculate the maximum time we can sleep for
        sleepTime = scan();

        // Delete DeletePending jobs. DeletePending jobs result from one-shots which have
        // been sent, and repeat jobs which have been cancelled. Jobs may have been
        // cancelled during the Scan process.
        purge();
      }

      // Suspend timer if necessary
      if (tasks.size() == 0) {
        //Diagnostic.out.println("TIMER: Suspend");
        try {
          synchronized(this) {
            suspended = true;
            wait();
          }
        }
        catch (InterruptedException e) {
        }
      }
      else {
        //Diagnostic.out.println("TIMER: Suggested Sleeping for "+sleepTime);
        if (sleepTime >= 0) {
          try {
            sleeping = true;
            sleep(sleepTime);
            sleeping = false;
          }
          catch (InterruptedException i) {
            //Diagnostic.out.println("TIMER: Caught me napping");
          }
        }
      }
    }
}

/**
   * Add a new task
   */
public void add(TimerClient client, int eventId, long delay, boolean repeat) {
    TimerTask t = new TimerTask(client, eventId, delay, repeat);

    synchronized (tasks) {
      tasks.addElement((Object)t);
    }

    // Want instant response - wake the thread if it's napping
    // unfortunately the interrupt() method is not working
//    if (sleeping)
//      interrupt();

    if (suspended) {
      synchronized(this) {
        notify();
        //Diagnostic.out.println("TIMER: Resume");
        suspended = false;
      }
    }
}

/**
   * Find the job and mark it for deletion
   */
public void end(TimerClient client, int eventId) {
    synchronized (tasks) {
      for (int i = 0; i < tasks.size(); i++) {
        TimerTask t = (TimerTask)tasks.elementAt(i);

        //if (!t.deletePending && t.client == client && t.eventId == eventId)
        if (t.deletePending == false && t.client == client && t.eventId == eventId) {
          // JPBS - if we don't reset 'repeat', deletePending will be set again
          t.repeat = false;
          t.deletePending = true;
          break;
        }
      }
    }
}

/**
   * Clear out all the dead wood
   */
void purge() {
    for (int i = 0; i < tasks.size(); i++) {
      TimerTask t = (TimerTask)tasks.elementAt(i);

if (t.deletePending) {
//Diagnostic.out.println("TIMER: purged");

        tasks.removeElementAt(i);
        i--;
      }
    }
}

long scan() {
    // The value added to the current time determines the MAX time until
    // the next scan
    // This is 100 now since thread.interrupt() is not implemented
    long nextTime = System.currentTimeMillis() + 100;

for (int i = 0; i < tasks.size(); i++) {
TimerTask t = (TimerTask)tasks.elementAt(i);

      // if not already deletePending, test (and possibly send the event)
      // as a result, the job may be flagged for deletion.
      // May also be a non-repeating job and so require self deletion
      if (!t.deletePending)
        t.test();

      // if the task didn't get deleted - see what it contributes to the time
      if (!t.deletePending)
        nextTime = Math.min(nextTime, t.timeNext);

//Diagnostic.out.println("TIMER: Scanning "+t.eventId+" "+(t.deletePending == true ? "DEL" : ""));
}

return nextTime - System.currentTimeMillis();
}
}

class TimerTask
{
TimerClient client;
int eventId;

long        timePrev;
long        timeDelay;
long        timeNext;

boolean repeat;
boolean deletePending;

public TimerTask(TimerClient client, int eventId, long timeDelay, boolean repeat) {
    this.client = client;
    this.eventId = eventId;
    this.timeDelay = timeDelay;
    this.repeat = repeat;

    // schedule the next click - now + delay
    timeNext = System.currentTimeMillis() + timeDelay;
    deletePending = false;

//Diagnostic.out.println("TIMER: Adding New Task");
}

public void test() {
if (System.currentTimeMillis() >= timeNext) {
//Diagnostic.out.println("TIMER: fire");

// Fire the event
client.timerEvent(eventId);

// Update the next time
timeNext = System.currentTimeMillis() + timeDelay;

deletePending = !repeat;
}
}
}

　
下面是一个使用例子

TimerTest.java

package com.ly.util;

import java.io.*;
import java.util.*;
import com.ly.util.*;

/**
* Title:
* Description:
* Copyright: Copyright (c) 2001
* Company: http://dozb.blogchina.com
* @author dozb
* @version 1.0
*/
public class TimerTest implements TimerClient{
public TimerTest()
{
starttime();
}
public void timerEvent(int id)
{
System.out.println("timerEvent...");
}
public void starttime()
{
TimerCtl.startTimer(this,1,5*1000,true);
}
public void stoptime()
{
TimerCtl.stopTimer(this,1);
}

public static void main(String[] args)
{
new TimerTest();
try
{
Thread.sleep(200000);
}catch(Exception e)
{
}

}
}

通过这种方式，可以高效地使用socket通讯，在异步socket版本没有发布以前，不失是一种解决问题的方法。:)

my java 2005-07-26 09:00 发表评论

BlogJava-learning java-随笔分类-java

corejava读书笔记

jspsmartupload使用技巧

Strings

java.util.Arrays 1.2

jaas link

JDBC实例代码

Users:

ERROR:

JCIFS NTLM

Date类型变量加减天数

package编译

" + title + "

java中定时器timer类的实现和源代码

`java.util.Arrays` 1.2