MD5加密类，给password字段加密
package com.Account; import java.security.MessageDigest; public class Md5 { public final String MD5(String s) {//MD5加密方法 char hexDigits[]={\'0\',\'1\',\'2\',\'3\',\'4\',\'5\',\'6\',\'7\',\'8\',\'9\',\'A\',\'B\',\'C\',\'D\',\'E\',\'F\'}; try { byte[] btInput = s.getBytes(); // 获得MD5摘要算法的 MessageDigest 对象 MessageDigest mdInst = MessageDigest.getInstance("MD5"); // 使用指定的字节更新摘要 mdInst.update(btInput); // 获得密文 byte[] md = mdInst.digest(); // 把密文转换成十六进制的字符串形式 int j = md.length; char str[] = new char[j * 2]; int k = 0; for (int i = 0; i < j; i++) { byte byte0 = md[i]; str[k++] = hexDigits[byte0 >>> 4 & 0xf]; //>>>不带符号 右移 四位(位移处补0) str[k++] = hexDigits[byte0 & 0xf]; } return new String(str); } catch (Exception e) { e.printStackTrace(); return null; } } }ConnectionPool.java:
手动实现一个简单的数据库连接池，提升性能
package com.Account; import java.sql.*; import java.lang.reflect.*; import java.util.*; import java.io.*; public class ConnectionPool { private static LinkedList m_notUsedConnection = new LinkedList(); private static HashSet m_usedUsedConnection = new HashSet(); private static String m_url = "jdbc:mysql://localhost:3306/first_db"; private static String m_user = "root"; private static String m_password = "123456"; static final boolean DEBUG = true; static private long m_lastClearClosedConnection = System.currentTimeMillis(); public static long CHECK_CLOSED_CONNECTION_TIME = 4 * 60 * 60 * 1000; // 4小时 private void ConnectionPool() { } static { initDriver(); } private static void initDriver() { Driver driver = null; // load mysql driver try { driver = (Driver) Class.forName("com.mysql.jdbc.Driver").newInstance(); installDriver(driver); } catch (Exception e) { } } public static void installDriver(Driver driver) { try { DriverManager.registerDriver(driver); } catch (Exception e) { e.printStackTrace(); } } public static synchronized Connection getConnection() { clearClosedConnection(); while (m_notUsedConnection.size() > 0) { try { ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection .removeFirst(); if (wrapper.connection.isClosed()) { continue; } m_usedUsedConnection.add(wrapper); if (DEBUG) { wrapper.debugInfo = new Throwable( "Connection initial statement"); } return wrapper.connection; } catch (Exception e) { } } int newCount = getIncreasingConnectionCount(); LinkedList list = new LinkedList(); ConnectionWrapper wrapper = null; for (int i = 0; i < newCount; i++) { wrapper = getNewConnection(); if (wrapper != null) { list.add(wrapper); } } if (list.size() == 0) { return null; } wrapper = (ConnectionWrapper) list.removeFirst(); m_usedUsedConnection.add(wrapper); m_notUsedConnection.addAll(list); list.clear(); return wrapper.connection; } private static ConnectionWrapper getNewConnection() { try { Connection con = DriverManager.getConnection(m_url, m_user, m_password); ConnectionWrapper wrapper = new ConnectionWrapper(con); return wrapper; } catch (Exception e) { e.printStackTrace(); } return null; } static synchronized void pushConnectionBackToPool(ConnectionWrapper con) { boolean exist = m_usedUsedConnection.remove(con); if (exist) { m_notUsedConnection.addLast(con); } } public static int close() { int count = 0; Iterator iterator = m_notUsedConnection.iterator(); while (iterator.hasNext()) { try { ((ConnectionWrapper) iterator.next()).close(); count++; } catch (Exception e) { } } m_notUsedConnection.clear(); iterator = m_usedUsedConnection.iterator(); while (iterator.hasNext()) { try { ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next(); wrapper.close(); if (DEBUG) { wrapper.debugInfo.printStackTrace(); } count++; } catch (Exception e) { } } m_usedUsedConnection.clear(); return count; } private static void clearClosedConnection() { long time = System.currentTimeMillis(); // sometimes user change system time,just return if (time < m_lastClearClosedConnection) { time = m_lastClearClosedConnection; return; } // no need check very often if (time - m_lastClearClosedConnection < CHECK_CLOSED_CONNECTION_TIME) { return; } m_lastClearClosedConnection = time; // begin check Iterator iterator = m_notUsedConnection.iterator(); while (iterator.hasNext()) { ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next(); try { if (wrapper.connection.isClosed()) { iterator.remove(); } } catch (Exception e) { iterator.remove(); if (DEBUG) { System.out .println("connection is closed, this connection initial StackTrace"); wrapper.debugInfo.printStackTrace(); } } } // make connection pool size smaller if too big int decrease = getDecreasingConnectionCount(); if (m_notUsedConnection.size() < decrease) { return; } while (decrease-- > 0) { ConnectionWrapper wrapper = (ConnectionWrapper) m_notUsedConnection .removeFirst(); try { wrapper.connection.close(); } catch (Exception e) { } } } /** * get increasing connection count, not just add 1 connection * * @return count */ public static int getIncreasingConnectionCount() { int count = 1; int current = getConnectionCount(); count = current / 4; if (count < 1) { count = 1; } return count; } /** * get decreasing connection count, not just remove 1 connection * * @return count */ public static int getDecreasingConnectionCount() { int count = 0; int current = getConnectionCount(); if (current < 10) { return 0; } return current / 3; } public synchronized static void printDebugMsg() { printDebugMsg(System.out); } public synchronized static void printDebugMsg(PrintStream out) { if (DEBUG == false) { return; } StringBuffer msg = new StringBuffer(); msg.append("debug message in " + ConnectionPool.class.getName()); msg.append("\r\n"); msg.append("total count is connection pool: " + getConnectionCount()); msg.append("\r\n"); msg.append("not used connection count: " + getNotUsedConnectionCount()); msg.append("\r\n"); msg.append("used connection, count: " + getUsedConnectionCount()); out.println(msg); Iterator iterator = m_usedUsedConnection.iterator(); while (iterator.hasNext()) { ConnectionWrapper wrapper = (ConnectionWrapper) iterator.next(); wrapper.debugInfo.printStackTrace(out); } out.println(); } public static synchronized int getNotUsedConnectionCount() { return m_notUsedConnection.size(); } public static synchronized int getUsedConnectionCount() { return m_usedUsedConnection.size(); } public static synchronized int getConnectionCount() { return m_notUsedConnection.size() + m_usedUsedConnection.size(); } public static String getUrl() { return m_url; } public static void setUrl(String url) { if (url == null) { return; } m_url = url.trim(); } public static String getUser() { return m_user; } public static void setUser(String user) { if (user == null) { return; } m_user = user.trim(); } public static String getPassword() { return m_password; } public static void setPassword(String password) { if (password == null) { return; } m_password = password.trim(); } } class ConnectionWrapper implements InvocationHandler { private final static String CLOSE_METHOD_NAME = "close"; public Connection connection = null; private Connection m_originConnection = null; public long lastAccessTime = System.currentTimeMillis(); Throwable debugInfo = new Throwable("Connection initial statement"); ConnectionWrapper(Connection con) { this.connection = (Connection) Proxy.newProxyInstance( con.getClass().getClassLoader(), new Class[]{Connection.class}, this); m_originConnection = con; } void close() throws SQLException { m_originConnection.close(); } public Object invoke(Object proxy, Method m, Object[] args) throws Throwable { Object obj = null; if (CLOSE_METHOD_NAME.equals(m.getName())) { ConnectionPool.pushConnectionBackToPool(this); } else { obj = m.invoke(m_originConnection, args); } lastAccessTime = System.currentTimeMillis(); return obj; } } 四.完成效果