Fun to Java

2014年4月22日星期二

【File I / O 處理 01】File 處理

File 類別並不是 I/O 中所定義在資料流處理的類別，但它可直接處理檔案 file 及檔案系統 (file system，即知道檔案在那個目錄 directory 之下）。

   方法                 功能
   _____________________________________________

 canRead             比較可否讀取檔案
   canWrite            比較可否寫入檔案
   compareTo           比較 2 個檔案路徑
   createNewFile       建新檔案
   createTempFile      建臨時檔案
   delete              刪除檔案路徑
   exists              判斷檔案存在否
   getName             取出檔案或路徑名稱
   isDirectory         判斷File物件是否為目錄
   length              檔案長度
   list                取出File名稱，以字串陣列表示
   renameTo            更改檔名
   setReadOnly         將檔案 / 目錄設定唯讀
   toString            取出檔案路徑字串
   toURL               將檔案路徑轉換成 URL 檔案
   _____________________________________________

檔案：FileIOIsFile.java

import java.io.File;
import java.util.Scanner;


public class FileIOIsFile {

 public static void main(String[] args) {
  String fileName, fileDir;
  
  System.out.println("請輸入檔名： ");
  Scanner sn = new Scanner(System.in);
  fileDir = sn.next();
  
  File file = new File(fileDir);
  if(file.isFile())
   System.out.println(file.getName()+" 是檔案");
  else if(file.isDirectory())
   System.out.println(file.getName()+" 是目錄");
  else {
   System.out.println("無此檔案或目錄");
   System.exit(0);
  }
 }

}

執行結果

輸入檔案名稱

輸入目錄名稱

【JDBC 01】下載 JDBC Driver，並連接 DB


import java.sql.*;

public class DBConn2 {

 public static void main(String[] args) {
  
  try {
   Class.forName("com.mysql.jdbc.Driver");
   System.out.println("Success loading JDBC-ODBC Bridge Driver");
  } catch (ClassNotFoundException e){
   System.out.println("JDBC 沒有驅動程式" + e.getMessage()); 
  }
  
  try { 
   
      String url =  "jdbc:mysql://localhost:3306/phone?" + 
                    "user=root&password=12345"; 
      Connection conn = DriverManager.getConnection(url); 
      if(!conn.isClosed()) 
          System.out.println("資料庫連線成功"); 

      conn.close(); 
  } 
  catch(SQLException e) { 
   System.out.println("資料庫連線失敗");
  }
 }

}

執行結果

【JDBC 00】安裝 XAMPP，JDBC Driver

1. 下載，並安裝 XAMPP: https://www.apachefriends.org/zh_tw/index.html
2. 下載 JDBC Driver，並加入 Project 的 Build Path 中 : https://dev.mysql.com/downloads/connector/j/
3. 設定 XAMPP 安全權限

 注意: 下列一定要設成 no，否則以 DriverManager.getConnection(url) 時，資料庫無法連接成功 

XAMPP:  MySQL is accessable via network. 
XAMPP: Normaly that's not recommended. Do you want me to turn it off? [yes] no



ElvisdeMacBook-Pro:~ root# whoami
root
ElvisdeMacBook-Pro:~ root# /Applications/XAMPP/xamppfiles/xampp security
XAMPP:  Quick security check...
XAMPP:  Your XAMPP pages are NOT secured by a password. 
XAMPP: Do you want to set a password? [yes] 
XAMPP: Password: 
XAMPP: Password (again): 
XAMPP:  Password protection active. Please use 'xampp' as user name!
XAMPP:  MySQL is accessable via network. 
XAMPP: Normaly that's not recommended. Do you want me to turn it off? [yes] no
XAMPP:  The MySQL/phpMyAdmin user pma has no password set!!! 
XAMPP: Do you want to set a password? [yes] 
XAMPP: Password: 
XAMPP: Password (again): 
XAMPP:  Setting new MySQL pma password.
XAMPP:  Setting phpMyAdmin's pma password to the new one.
XAMPP:  MySQL has no root passwort set!!! 
XAMPP: Do you want to set a password? [yes] 
XAMPP:  Write the password somewhere down to make sure you won't forget it!!! 
XAMPP: Password: 
XAMPP: Password (again): 
XAMPP:  Setting new MySQL root password.

【JDBC 00】建立資料庫

DB 操作:

查詢: show databases;
新增: create database Database_Name;
刪除: drop database Database_Name;
開啓: use Database_Name;

Table 操作:

新增: create table Table_Name ( ... );
查詢全部: show tables;
刪除: drop table Table_Name;

Schema :

查詢表格: show columns from Table_Name;

Data:

新增: insert into Table_Name(no,name) values (1,'Tom');

以 root 帳號登入

ElvisdeMacBook-Pro:bin elvismeng$ pwd
/Applications/XAMPP/bin
ElvisdeMacBook-Pro:bin elvismeng$ ./mysql -u root -p
Enter password: 
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 56
Server version: 5.6.16 Source distribution

Copyright (c) 2000, 2014, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

mysql>

新增資料庫

mysql> CREATE DATABASE phone;
Query OK, 1 row affected (0.01 sec)

mysql>

開啟資料庫

mysql> use phone;
Database changed
mysql>

新增資料表 Table


mysql> CREATE TABLE student (
    -> ID integer,
    -> name char(30)
    -> );
Query OK, 0 rows affected (0.07 sec)

mysql>

查詢資料庫所有資料表 Table

mysql> show tables;
+-----------------+
| Tables_in_phone |
+-----------------+
| student         |
+-----------------+
1 row in set (0.00 sec)

mysql>

查詢指定的資料表 Table

mysql> SHOW COLUMNS FROM student;
+-------+----------+------+-----+---------+-------+
| Field | Type     | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| ID    | int(11)  | YES  |     | NULL    |       |
| name  | char(30) | YES  |     | NULL    |       |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.01 sec)

mysql>

新增資料 Table

mysql> INSERT INTO student (ID, name) values (1,'Tom');
Query OK, 1 row affected (0.01 sec)

mysql> INSERT INTO student (ID, name) values (2,'Bob');
Query OK, 1 row affected (0.01 sec)

mysql> INSERT INTO student (ID, name) values (3,'Joe');
Query OK, 1 row affected (0.01 sec)

mysql>

查詢輸入資料 Table

mysql> SELECT * FROM student;
+------+------+
| ID   | name |
+------+------+
|    1 | Tom  |
|    2 | Bob  |
|    3 | Joe  |
+------+------+
3 rows in set (0.01 sec)

mysql>

Reference:
http://bonny.com.tw/web/xampp/0603newmysql.htm

【JDBC 03】異動資料：新㽪、修改、刪除


import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

import javax.swing.JOptionPane;

import com.mysql.jdbc.Statement;


public class DBConn4 {

 public static void main(String[] args) {
  try {
   Class.forName("com.mysql.jdbc.Driver");
   System.out.println("Success loading JDBC-ODBC Bridge Driver");
  } catch (ClassNotFoundException e){
   System.out.println("JDBC 沒有驅動程式" + e.getMessage()); 
  }
  
  int op = 0;
  String sqlstr ="",id="",name="";
  try {
   op = Integer.parseInt(JOptionPane.showInputDialog("請選擇選單\n1: 新增 2:修改 3:刪除"));
   
   switch(op){
   case 1:
    id = JOptionPane.showInputDialog("請輸入座號");
    name = JOptionPane.showInputDialog("請輸姓名").replace("'", "'");
    sqlstr = "INSERT INTO student(ID,name) VALUES (" +
              id  + ",'"+ name + "'" + ")";
    break;
   case 2:
    id = JOptionPane.showInputDialog("請輸入欲修改資料(以座號為依據)");
    name = JOptionPane.showInputDialog("請輸姓名").replace("'", "'");
    sqlstr = "UPDATE student SET name='" + name +"'" +
             "WHERE ID = "+ id;
    break;
   case 3:
    id = JOptionPane.showInputDialog("請輸入欲刪除資料(以座號為依據)");
    sqlstr = "DELETE FROM student WHERE ID="+id;
    break;
   default:
    System.out.println("Error");
   }
  }catch(NumberFormatException e){
   
  }
  
  
  try { 
   
      String url =  "jdbc:mysql://localhost:3306/phone?" + 
                    "user=root&password=12345"; 
      Connection conn = DriverManager.getConnection(url); 
      if(!conn.isClosed()) 
          System.out.println("資料庫連線成功"); 
      
      Statement sm = (Statement) conn.createStatement();
      if(op !=0){
       sm.execute(sqlstr);
      }
      
      ResultSet rs = sm.executeQuery("SELECT * FROM student");
      ResultSetMetaData rsmd = rs.getMetaData();
      for(int i=1; i <= rsmd.getColumnCount(); i++){
       System.out.print(rsmd.getColumnName(i)+"\t");
      }
      System.out.println("\n---------------------");
      while(rs.next()){
       System.out.print(rs.getInt(1) + "\t" +
                           rs.getString(2));
       System.out.println();
      }
      
            sm.close();
      conn.close(); 
  } 
  catch(SQLException e) { 
   System.out.println("資料庫連線失敗");
  }
 }

}

執行結果
新增

修改

刪除

【JDBC 02】查詢資料

import java.sql.*;

import com.mysql.jdbc.Statement;

public class DBConn3 {

 public static void main(String[] args) {
  
  try {
   Class.forName("com.mysql.jdbc.Driver");
   System.out.println("Success loading JDBC-ODBC Bridge Driver");
  } catch (ClassNotFoundException e){
   System.out.println("JDBC 沒有驅動程式" + e.getMessage()); 
  }
  
  try { 
   
      String url =  "jdbc:mysql://localhost:3306/phone?" + 
                    "user=root&password=12345"; 
      Connection conn = DriverManager.getConnection(url); 
      if(!conn.isClosed()) 
          System.out.println("資料庫連線成功"); 
      
      Statement sm = (Statement) conn.createStatement();
      ResultSet rs = sm.executeQuery("SELECT * FROM student");
      ResultSetMetaData rsmd = rs.getMetaData();
      for(int i=1; i <= rsmd.getColumnCount(); i++){
       System.out.print(rsmd.getColumnName(i)+"\t");
      }
      System.out.println("\n---------------------");
      while(rs.next()){
       System.out.print(rs.getInt(1) + "\t" +
                           rs.getString(2));
       System.out.println();
      }
      
            sm.close();
      conn.close(); 
  } 
  catch(SQLException e) { 
   System.out.println("資料庫連線失敗");
  }
 }

}

執行結果

2014年4月21日星期一

【File I / O 處理 02】Reader 類別

Reader 類別處理字元資料流讀取。

    方法                      功能
   _______________________________________________________

    close()                  關閉資料流
    mark(int numChars)       在資料流中標示目前的位置
    read()                   讀取 1 個字元
    read(char[] buffer)      將讀取的字元陣列放在buffer陣列中
    ready()                  檢查資料流是否準備好讀取
    reset()                  重置資料流
    skip(long n)             跳過 n 個字元
   _______________________________________________________


import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Scanner;


public class FileIOFileReader {

 public static void main(String[] args) {
  try{
   String fileName, fileDir;
   
   System.out.println("請輸入檔名： ");
   Scanner sn = new Scanner(System.in);
   fileDir = sn.next();
  
   char[] buffer = new char[100];
   FileReader file = new FileReader(fileDir);
   file.read(buffer);
   System.out.println(buffer);
   file.close();
  } catch (IOException e) {
   // TODO Auto-generated catch block
   System.out.println("輸入檔案路徑錯誤");
  }
  
 }

}

執行結果

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2014年4月22日 星期二

2014年4月21日 星期一

2014年4月22日星期二

2014年4月21日星期一