gistfile1.txt

# 日期操作
# 取得今天日期格式
public static String getDateString(int dateOffset) {
	Calendar cal = Calendar.getInstance();
	cal.add(Calendar.DATE, dateOffset);
	SimpleDateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");
	String s = format1.format(cal.getTime());
	s += "(" + dayMapping[cal.get(Calendar.DAY_OF_WEEK) - 1] + ")";
	return s;
}

# 現在的 timestamp
public static Timestamp currentTimeStamp() {
	 java.util.Date date= new java.util.Date();
	 return new Timestamp(date.getTime());
}

gistfile2.txt

# Get URL Content to String
public static String getText(String url) throws Exception {
	URL website = new URL(url);
	URLConnection connection = website.openConnection();
	BufferedReader in = new BufferedReader(
	                        new InputStreamReader(
	                            connection.getInputStream()));
	
	StringBuilder response = new StringBuilder();
	String inputLine;
	
	while ((inputLine = in.readLine()) != null) 
	    response.append(inputLine);
	
	in.close();
	
	return response.toString();
}

gistfile3.txt

# Program Running Time
# 計算執行時間
long startTime = System.currentTimeMillis();
.....your program....
long endTime   = System.currentTimeMillis();
long totalTime = endTime - startTime;
System.out.println(totalTime);

Java Reference

# MySQL 連線
String driver = "com.mysql.jdbc.Driver";
Class.forName(driver);
String conUrl = "jdbc:mysql://localhost/smft?user=root&password=&charset=utf8&characterEncoding=UTF-8r";
Connection con = null;
PreparedStatement ps = conn.prepareStatement(SQL);
ResultSet rs = pstmt.executeQuery();
while (rs.next()) {
    rs.getString("UserName");
}

# MS SQL 連線
String conUrl = "jdbc:sqlserver://10.57.35.33:1433;databaseName=SmftService;user=SmftDeveloper;password=SmftDeveloper";
Connection con = DriverManager.getConnection(conUrl);

# URL Download 和 NIO 寫檔
String fileName = ParserUtils.parseFileName(logFilePath);
System.out.println("Downloading " + fileName);
URL website = new URL(Settings.FILE_WEBSITE_URL + logFilePath);
ReadableByteChannel rbc = Channels.newChannel(website.openStream());
String filePath = logDirectory.getPath() + "/" + fileName;
File file = new File(filePath);
if(!file.exists()) {
    file.createNewFile();
}
FileOutputStream fos = new FileOutputStream(file, false);
fos.getChannel().transferFrom(rbc, 0, Long.MAX_VALUE);
fos.close();

# Date 轉 Timestamp 字串
DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = new Date();
String timestamp = dateFormat.format(date);

# 從整串檔案路徑中取得 Filename
public static String parseFileName(String path) {
    int ind = path.lastIndexOf("/");
    return path.substring(ind+1, path.length());
}

# POI 基本操作
XSSFWorkbook workbook = new XSSFWorkbook();
XSSFSheet spreadsheet = workbook.createSheet(name);
spreadsheet.createRow(0).createCell(0).setCellValue("PID");
String startColumn = CellReference.convertNumToColString(1);
String endColumn = CellReference.convertNumToColString(2);
CellRangeAddress region = CellRangeAddress.valueOf(startColumn + "1:" + endColumn + "1");
spreadsheet.addMergedRegion(region);
spreadsheet.getRow(0).createCell(CellReference.convertColStringToIndex(startColumn)).setCellValue(pid);
FileOutputStream out = new FileOutputStream(new File("Writesheet.xlsx

# String Array Join
public static String combine(String[] s, String glue) {
    int k = s.length;
    if (k == 0) {
        return null;
    }
    StringBuilder out = new StringBuilder();
    out.append(s[0]);
    for (int x = 1; x < k; ++x) {
        out.append(glue).append(s[x]);
    }
    return out.toString();
}

SQL IN

List<String> imei = new ArrayList<String>();
public static String SQL_LOG_URL_QUERY = "SELECT * FROM log WHERE imei IN (%s)";
String querySQL = String.format(Settings.SQL_LOG_URL_QUERY, SQLUtils.preparePlaceHolders(imei.size()));
stmt = conn.prepareStatement(querySQL);
SQLUtils.setPlaceHoldersValues(stmt, imei.toArray());

public class SQLUtils {

    public static String preparePlaceHolders(int length) {
        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < length;) {
            builder.append("?");
            if (++i < length) {
                builder.append(",");
            }
        }
        return builder.toString();
    }

    public static void setPlaceHoldersValues(PreparedStatement preparedStatement, Object... values) throws SQLException {
        for (int i = 0; i < values.length; i++) {
            preparedStatement.setObject(i + 1, values[i]);
        }
    }
}

寄信

Properties properties = System.getProperties();
properties.setProperty("mail.smtp.host", host);

Session session = Session.getDefaultInstance(properties);

// Create a default MimeMessage object.
MimeMessage message = new MimeMessage(session
message.addRecipient(Message.RecipientType.TO, new InternetAddress("Hello@example.com"));

StringBuffer sb = new StringBuffer();
sb.append("<HTML>\n");
sb.append("<BODY>\n");
sb.append(summary);
sb.append("</BODY>\n");
sb.append("</HTML>\n");

message.setDataHandler(new DataHandler(new ByteArrayDataSource(sb.toString(), "text/html")));

// Send message
Transport.send(message);

檔案操作

BufferedReader reader = null;
OutputStreamWriter writer = null;
String inFileName = "filename";

try {
	
	File inFile = new File(inFileName);
	InputStream is = new FileInputStream(inFile);
	reader = new BufferedReader(new InputStreamReader(is));
	
	File outFile = new File(inFileName + ".out");
	OutputStream os = new FileOutputStream(outFile);
	writer = new OutputStreamWriter(os);
	
	String str = "";
	while((str = reader.readLine()) != null) {
	}
	
	reader.close();
	writer.close();
	
} catch (FileNotFoundException e) {
	e.printStackTrace();
} catch (IOException e) {
	e.printStackTrace();
} finally {
	
	if(reader != null) {
		try {
			reader.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	if(writer != null) {
		try {
			writer.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}