2009年4月17日
import java.io.*;
/**
* A simple output class to write values to a file of characters.
* If any file errors occur, methods in this class will display
* an error message and terminate the program.
*
* @version 1.1 1999.09.10
* @author Graham Roberts
* @author Russel Winder
*
*/
public class FileOutput {
/**
* Instance variables to store file name.
*/
private String filename = "";
/**
* Instance variables to store stream.
*/
private BufferedWriter writer = null;
/**
* Construct <CODE>FileOutput</CODE> object given a file name.
*/
public FileOutput(final String name) {
filename = name;
try {
writer = new BufferedWriter(new FileWriter(filename));
}
catch(IOException e) {
error("Can't open file: " + filename);
}
}
/**
* Construct <CODE>FileOutput</CODE> object given a
* <CODE>File</CODE> object..
*/
public FileOutput(final File file) {
filename = file.getName();
try {
writer = new BufferedWriter(new FileWriter(filename));
}
catch(IOException e) {
error("Can't open file: " + filename);
}
}
/**
* Close the file when finished
*/
public final synchronized void close() {
try {
writer.close();
}
catch(IOException e) {
error("Can't close file: " + filename);
}
}
/**
* Write an <CODE>int</CODE> value to a file.
*/
public final synchronized void writeInteger(final int i) {
try {
writer.write(Integer.toString(i));
}
catch(IOException e) {
error("writeInteger failed for file: " + filename);
}
}
/**
* Write an <CODE>long</CODE> value to a file.
*/
public final synchronized void writeLong(final long l) {
try {
writer.write(Long.toString(l));
}
catch(IOException e) {
error("writeLong failed for file: " + filename);
}
}
/**
* Write an <CODE>double</CODE> value to a file.
*/
public final synchronized void writeDouble(final double d) {
try {
writer.write(Double.toString(d));
}
catch(IOException e) {
error("writeDouble failed for file: " + filename);
}
}
/**
* Write an <CODE>float</CODE> value to a file.
*/
public final synchronized void writeFlaot(final float f) {
try {
writer.write(Float.toString(f));
}
catch(IOException e) {
error("writeFloat failed for file: " + filename);
}
}
/**
* Write an <CODE>char</CODE> value to a file.
*/
public final synchronized void writeCharacter(final char c) {
try {
writer.write(c);
}
catch(IOException e) {
error("writeCharacter failed for file: " + filename);
}
}
/**
* Write an <CODE>string</CODE> value to a file.
*/
public final synchronized void writeString(final String s) {
try {
writer.write(s);
}
catch(IOException e) {
error("writeString failed for file: " + filename);
}
}
/**
* Write a newline to a file.
*/
public final synchronized void writeNewline() {
try {
writer.write('\n');
}
catch(IOException e) {
error("writeNewline failed for file: " + filename);
}
}
/**
* Deal with a file error
*/
private void error(String msg) {
System.err.println(msg);
System.err.println("Unable to continue executing program.");
System.exit(0);
}
}
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
/**
* This class provides a basic window, with a quit button, that can
* be used to create simple GUIs.
*
* @version 1.1 2000.01.07
* @author Graham Roberts
* @author Russel Winder
*/
public class DrawFrame extends JFrame {
/**
* Override of the method to add a <CODE>JPanel</CODE> to the
* <CODE>DrawFrame</CODE> so that the <CODE>JPanel</CODE> is
* centred.
*/
public void add(final JPanel panel) {
getContentPane().add(panel, BorderLayout.CENTER);
}
/**
* Terminate the program when the user wants to quit.
*/
private void quit() {
System.exit(0);
}
/**
* construct a <CODE>DrawFrame</CODE>
*/
public DrawFrame(final String title) {
// Initialize the JFrame ensuring the titlebar is set.
super(title);
// Set up the quit button with it's listener.
Button quitButton = new Button("Quit");
quitButton.addActionListener(new ActionListener() {
public void actionPerformed(final ActionEvent e) {
quit();
}
});
// put all the buttons into a JPanel.
JPanel buttonPanel = new JPanel(new FlowLayout());
buttonPanel.add(quitButton);
// Create the contents of the frame. Use BorderLayout with the
// top (Center) part being the drawing area and the bottom
// (South) strip holding a quit button.
getContentPane().setLayout(new BorderLayout());
getContentPane().add(buttonPanel, BorderLayout.SOUTH);
// Ensure that windows close events from the window manager are
// caught and acted upon.
addWindowListener(new WindowAdapter() {
public void windowClosing(final WindowEvent evt) {
quit();
}
});
}
/**
* Position a window in the centre of the screen.
*/
public void centreOnScreen() {
Dimension displaySize = getToolkit().getScreenSize();
Dimension windowSize = getSize();
int x = (displaySize.width - windowSize.width) / 2;
int y = (displaySize.height - windowSize.height) / 2;
if(x < 0) {
x = 0;
}
if(y < 0) {
y = 0;
}
setLocation(x,y);
}
}
2009年4月2日
import java.awt.*;
import javax.swing.*;
/**
* A <CODE>JPanel</CODE> with a default size. Subclasses must
* override the <CODE>paint</CODE> method which has signature.
*
* <PRE> public void paint(final Graphics g) </PRE>
*
* @version 1.0 1999.09.04
* @author Graham Roberts
* @author Russel Winder
*/
public class DrawPanel extends JPanel{
/**
* The width of the panel.
*/
private int width = 300;
/**
* The height of the panel
*/
private int height = 300;
/**
* Default constructor, uses the default size.
*/
protected DrawPanel() {
setPreferredSize(new Dimension(width, height));
}
/**
* Constructor for a size determined by the user.
*/
protected DrawPanel(final int w, final int h) {
width = w;
height = h;
setPreferredSize(new Dimension(width, height));
}
/**
* Accessor for the width of the panel.
*/
public int getHeight() {
return height;
}
}
2009年3月3日
import java.io.*;
/**
* A simple input class to read values from a file of characters. If
* any file errors occur, methods in this class will display an error
* message and terminate the program.
*
* @version 1.1 1999.09.10
* @author Graham Roberts
* @author Russel Winder
*/
public class FileInput {
/**
* Instance variables to store the name of the file we are
* associated with.
*/
private String filename = "";
/**
* Instance variables for the filestream associated with the file
* that we are associated with.
*/
private BufferedReader reader = null;
/**
* Instance variables to store current state of EOF.
*/
private boolean eof = false;
/**
* Construct <CODE>FileInput</CODE> object given a file name.
*/
public FileInput(final String fname) {
filename = fname;
try {
reader = new BufferedReader(new FileReader(filename));
}
catch (FileNotFoundException e) {
error("Can't open file: " + filename);
}
}
/**
* Construct <CODE>FileInput</CODE> object given a
* <CODE>File</CODE> object.
*/
public FileInput(final File file) {
filename = file.getName();
try {
reader = new BufferedReader(new FileReader(file));
}
catch (FileNotFoundException e) {
error("Can't open file: " + filename);
}
}
/**
* Close the file when finished
*/
public final synchronized void close() {
try {
reader.close();
}
catch(IOException e) {
error("Can't close file: " + filename);
}
}
/**
* Return true if the end of file has been reached.
*/
public boolean eof() {
return eof;
}
/**
* Read an <CODE>int</CODE> value from file. The default
* return value is 0.
*/
public final synchronized int readInteger() {
String input = "";
int value = 0;
try {
input = reader.readLine();
}
catch(IOException e) {
error("readInteger failed for file: " + filename);
}
if(input == null) {
eof = true;
}
else {
try {
value = Integer.parseInt(input);
}
catch(NumberFormatException e) {}
}
return value;
}
/**
* Read an <CODE>long</CODE> value from file. The default
* return value is 0L.
*/
public final synchronized long readLong() {
String input = "";
long value = 0L;
try {
input = reader.readLine();
}
catch(IOException e) {
error("readLong failed for file: " + filename);
}
if(input == null) {
eof = true;
}
else {
try {
value = Long.parseLong(input);
}
catch(NumberFormatException e) {}
}
return value;
}
/**
* Read an <CODE>double</CODE> value from file. The default
* return value is 0.0.
*/
public final synchronized double readDouble() {
String input = "";
double value = 0.0D;
try {
input = reader.readLine();
}
catch(IOException e) {
error("readDouble failed for file: " + filename);
}
if(input == null) {
eof = true;
}
else {
try {
value = Double.parseDouble(input);
}
catch(NumberFormatException e) {}
}
return value;
}
/**
* Read an <CODE>long</CODE> value from file. The default
* return value is 0L.
*/
public final synchronized float readFloat() {
String input = "";
float value = 0.0F;
try {
input = reader.readLine();
}
catch(IOException e) {
error("readFloat failed for file: " + filename);
}
if(input == null) {
eof = true;
}
else {
try {
value = Float.parseFloat(input);
}
catch(NumberFormatException e) {}
}
return value;
}
/**
* Read an <CODE>char</CODE> value from file. The default
* return value is ' '(space)
*/
public final synchronized char readCharacter() {
char c = ' ';
try {
int n = reader.read();
if (n == -1) {
eof = true;
}
else {
c = (char)n;
}
}
catch (IOException e) {
error("readCharacter failed for file: " + filename);
}
return c;
}
/**
* Read an <CODE>String</CODE> value from file. The default
* return value is ""(the empty string).
*/
public final synchronized String readString() {
String s = "";
try {
s = reader.readLine();
}
catch (IOException e) {
error("readString failed for file: " + filename);
}
if (s == null) {
eof = true;
s = "";
}
return s;
}
/**
* Deal with a file error, write a message and terminate.
*/
private void error(String msg) {
System.err.println(msg);
System.err.println("Unable to continue executing program.");
System.exit(0);
}
}
2009年2月18日
import java.io.*;
/**
* A simple input class to read values typed at the command line. If
* an error occurs during intput, any exceptions thrown are caught and
* a default value returned.
*
* @version 1.1 1998.08.18
* @author Graham Roberts
* @author Russel Winder
*/
public class keyboardInput {
/**
* The buffered stream that works the keyboard so that we can read
* from it sensibly
*/
private final BufferedReader in =
new BufferedReader(new InputStreamReader(System.in));
/**
* Read an <CODE>int</CODE> value from keyboard input. The default
* return value is 0.
*/
public final synchronized int readInteger() {
String input = "";
int value = 0;
try {
input = in.readLine();
}
catch (IOException e) { }
if (input != null) {
try {
value = Integer.parseInt(input);
}
catch (NumberFormatException e) { }
}
return value;
}
/**
* Read a <CODE>long</CODE> value from keyboard input. The default
* return value is 0L.
*/
public final synchronized long readLong() {
String input = "";
long value = 0L;
try {
input = in.readLine();
}
catch (IOException e) { }
if (input != null) {
try {
value = Long.parseLong(input);
}
catch (NumberFormatException e) { }
}
return value;
}
/**
* Read a <CODE>double</CODE> value from keyboard input. The default
* return value is 0.0
*/
public final synchronized double readDouble() {
String input = "";
double value = 0.0D;
try {
input = in.readLine();
}
catch (IOException e) { }
if (input != null) {
try {
value = Double.parseDouble(input);
}
catch (NumberFormatException e) { }
}
return value;
}
/**
* Read a <CODE>float</CODE> value from keyboard input. The default
* return value is 0.0F
*/
public final synchronized float readFloat() {
String input = "";
float value = 0.0F;
try {
input = in.readLine();
}
catch (IOException e) { }
if (input != null) {
try {
value = Float.parseFloat(input);
}
catch (NumberFormatException e) { }
}
return value;
}
/**
* Read a <CODE>char</CODE> value from keyboard input. The default
* return value is ' ' (space)
*/
public final synchronized char readCharacter() {
char c = ' ';
try {
c = (char)in.read();
}
catch (IOException e) { }
return c;
}
/**
* Read a <CODE>String</CODE> value from keyboard input. The default
* return value is "" (the empty string).
*/
public final synchronized String readString() {
String s = "";
try {
s = in.readLine();
}
catch (IOException e) { }
if (s == null) {
s = "";
}
return s;
}
}
2008年9月25日
折腾了一下午，外加半个晚上，终于把数据从局域网内的服务器调出来了！
问题是这样的，通过Oracle Sql Developer,我把数据表ChemicalComposition建立在隔壁小浩的Oracle服务器上，然后我这台客户机上想利用C#程序调用其中的ChemicalComposition。
关键代码片段如下
using (OracleConnection AGConnection = new OracleConnection(connectionString))
{
OracleCommand AGCommand = AGConnection.CreateCommand();
AGCommand.CommandText = "SELECT * FROM ""ChemicalComposition""";
OracleDataAdapter dataAdapter = new OracleDataAdapter(AGCommand);
dataAdapter.Fill(AlloyGradeTable);
} // AGConnection.Dispose called automatically.
其实这段代码拷到网页页面上有点失真，
AGCommand.CommandText = "SELECT * FROM ""ChemicalComposition""";
在Visual Studio中是：
AGCommand.CommandText = "SELECT * FROM \"ChemicalComposition\"";
下午一直用 "SELECT * FROM ChemicalComposition"做程序中的查询语句，结果报错为：
ORA-00942: table or view does not exist
老是以为数据库连接有错，根本就没有考虑sql语句出错！
如果在Oracle Sql Developer使用SELECT * FROM ChemicalComposition，结果报错为：
An error was encountered performing the requested operation:
ORA-00942: table or view does not exist
00942. 00000 - "table or view does not exist"
*Cause:
*Action:
Error at Line:1 Column:14
到晚上才明白，sql语句有错，因为之前也知道在 Oracle Sql Developer中sql语句的表名是要加双引号的，就是说使用SELECT * FROM "ChemicalComposition"可以从数据库中成功地调出数据。
很好，问题的根源找到，那么怎么在C#程序中写sql语句呢？一开始我写成：
AGCommand.CommandText = "SELECT * FROM ""ChemicalComposition""";
当然是行不通的，该错误Visual Studio轻易捕获，接着有改成：
AGCommand.CommandText = "SELECT * FROM " + ""ChemicalComposition"" + """;
还是不行，通不过！
后来在网上一顿猛搜，原来在字符串中的双引号"要用反斜杠加双引号\"表示！我靠！这个不是在C语言中学过么？？？真是个极其弱智的问题！
这种问题在用C语言编程时就碰到过，为何到C#中却不加注意？这是经验不足么？还是缺乏变通能力？
2008年9月17日
2008年9月9日