【转】20个开发人员十分有用的Java功能代码

【转】20个开发人员非常有用的Java功能代码

http://www.cn-java.com/www1/?viewnews-78759

1. 把Strings转换成int和把int转换成String

//integer to numeric string
String a = String.valueOf(2); 

//numeric string to an int  
int i = Integer.parseInt(a);

2. 向Java文件中添加文本

public void write(){
		
		BufferedWriter out = null;  
		try {  
			out = new BufferedWriter(new FileWriter("filename", true));  
			out.write("aString");  
		} catch (IOException e) { 
			if (out != null) {  
				try {
					out.close();
				} catch (IOException e1) {
					// TODO Auto-generated catch block
					e1.printStackTrace();
				} 
			}
		}
	}

3. 获取Java现在正调用的方法名

String methodName =Thread.currentThread().getStackTrace()[1].getMethodName();

4. 在Java中将String型转换成Date型

public Date str2Date(){
		SimpleDateFormat format = new SimpleDateFormat( "dd.MM.yyyy" );  
		Date date = null;
		try {
			date = format.parse("12.12.2012");
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} 
		return date;
	}

5. 通过Java JDBC链接Oracle数据库

public class OracleJdbcTest  {  
		String driverClass = "oracle.jdbc.driver.OracleDriver";  
		Connection con;  
		
		public void init(FileInputStream fs) throws ClassNotFoundException,SQLException, FileNotFoundException, IOException  {  
			Properties props = new Properties();
			props.load(fs);  
			String url = props.getProperty("db.url");
			String userName = props.getProperty("db.user");  
			String password = props.getProperty("db.password");  
			Class.forName(driverClass);  
			con=DriverManager.getConnection(url,userName, password);  
		}  
		
		public void fetch() throws SQLException,IOException  {  
			PreparedStatement ps = con.prepareStatement("select SYSDATE from dual");  
			ResultSet rs = ps.executeQuery();  
			while (rs.next())  {  
				// do the thing you do  
			
			}

			rs.close();  ps.close();  
		}  
		public static void main(String[] args)  {  
			OracleJdbcTest test = new OracleJdbcTest();  
			test.init();  
			test.fetch();  
		}  
	}

6.将Java中的util.Date转换成sql.Date

这一片段显示如何将一个java util Date转换成sql Date用于数据库

java.util.Date utilDate = new java.util.Date();  
java.sql.Date sqlDate = new java.sql.Date(utilDate.getTime());

7. 使用NIO快速复制Java文件

【转】20个开发人员十分有用的Java功能代码

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