/*** Sets the current thread's copy of this thread-local variable* to the specified value.  Most subclasses will have no need to* override this method, relying solely on the {@link #initialValue}* method to set the values of thread-locals.** @param value the value to be stored in the current thread's copy of*        this thread-local.*/public void set(T value) {//获取当前线程Thread t = Thread.currentThread();//得到线程的ThredLocalMapThreadLocalMap map = getMap(t);//如果map不为空，则将当前线程的对象作为key,传进来的参数作为value存储if (map != null)map.set(this, value);elsecreateMap(t, value);}

static class ThreadLocalMap {/*** The entries in this hash map extend WeakReference, using* its main ref field as the key (which is always a* ThreadLocal object).  Note that null keys (i.e. entry.get()* == null) mean that the key is no longer referenced, so the* entry can be expunged from table.  Such entries are referred to* as "stale entries" in the code that follows.*/static class Entry extends WeakReference<ThreadLocal<?>> {/** The value associated with this ThreadLocal. */Object value;Entry(ThreadLocal<?> k, Object v) {super(k);value = v;}}.......

public T get() {Thread t = Thread.currentThread();ThreadLocalMap map = getMap(t);if (map != null) {ThreadLocalMap.Entry e = map.getEntry(this);if (e != null) {@SuppressWarnings("unchecked")T result = (T)e.value;return result;}}return setInitialValue();}

public class ConnectionUtil {private static Logger logger = LoggerFactory.getLogger(ConnectionUtil.class);//数据库连接池private static BasicDataSource dataSource;//为不同的线程管理连接private static ThreadLocal<Connection> local;static {BufferedReader br = null;Properties ipp_prop = new Properties();try {String propertiesurl = System.getProperty("user.dir") + "/ipp_parser.properties";br = new BufferedReader(new InputStreamReader(new FileInputStream(new File(propertiesurl)), "utf-8"));ipp_prop.load(br);br.close();}  catch (Exception e1) {e1.printStackTrace();}dataSource = new BasicDataSource();dataSource.setDriverClassName(ipp_prop.getProperty("db.driver"));dataSource.setUrl(ipp_prop.getProperty("db.url"));dataSource.setUsername(ipp_prop.getProperty("db.user"));dataSource.setPassword(ipp_prop.getProperty("db.password"));//初始连接dataSource.setInitialSize(Integer.parseInt(ipp_prop.getProperty("db.initsize")));//最大连接dataSource.setMaxTotal(Integer.parseInt(ipp_prop.getProperty("db.maxtotal")));//最长等待时间dataSource.setMaxWaitMillis(Integer.parseInt(ipp_prop.getProperty("db.maxwait")));//最小空闲dataSource.setMinIdle(Integer.parseInt(ipp_prop.getProperty("db.minidle")));dataSource.setMaxIdle(Integer.parseInt(ipp_prop.getProperty("db.maxidle")));//初始化线程池本地local = new ThreadLocal<>();/**得到连接* @return* @throws SQLException*/public static Connection getOracleConnection() throws SQLException {//获取Connection对象Connection connection = dataSource.getConnection();//把Connection放进local里
        local.set(connection);logger.info("get oracleConnection");return connection;}public static void closeOracleConnection(){Connection connection = local.get();try {if (connection != null) {//设置自动提交connection.setAutoCommit(true);//连接还给连接池
                connection.close();local.remove();logger.info("close oracleConnection");}} catch (SQLException e) {e.printStackTrace();}}
}