JavaBasic-ThreadLocal

/**
 * Created by Neko on 2017/11/9.
 */
public class ThreadL1 {
    //通过匿名内部类覆盖ThreadLocal的initialValue()方法，指定初始值
    private static ThreadLocal<Integer> seqNum = new ThreadLocal<Integer>(){
        public Integer initialValue(){
            return 0;
        }
    };

    //获取下一个序列值
    public int getNextNum(){
        System.out.println("____"+seqNum.get());
        seqNum.set(seqNum.get()+1);
        return seqNum.get();
    }

    public static void main(String[] args) {
        ThreadL1 tl = new ThreadL1();
        //三个线程共享tl，各自产生序列号
        TestClient t1 = new TestClient(tl);
        TestClient t2 = new TestClient(tl);
        TestClient t3 = new TestClient(tl);

        t1.start();
        t2.start();
        t3.start();
   }

    private static class TestClient extends Thread{
        private ThreadL1 tl;
        public TestClient(ThreadL1 tl){
            this.tl = tl;
        }

        public void run(){
            for (int i = 0; i<3 ;i++){
                //每个线程打出3个序列值
                //currentThread()获取当前运行的线程对象
                System.out.println("Thread["+Thread.currentThread().getName()+"]--->tl["+tl.getNextNum()+"]");
            }
        }
    }
}

/**
 * Created by Neko on 2017/11/9.
 */
public class ThreadL2 {

    private Connection conn;//一个非线程安全的变量

    public void addTopic1() throws SQLException{
        Statement statement = conn.createStatement();//引用非线程安全变量
    }

    //--------------------->使用ThreadLocal这个connection这个非线程安全进行改造

    public static ThreadLocal<Connection> connThreadLocal = new ThreadLocal<Connection>();

    public static Connection getConnection(){
        //如果connThreadLocal没有本线程对应的Connection创建一个新的Connection
        //并将其保存到线程本地变量中
        if(connThreadLocal.get() == null){
            Connection conn = getConnection();
            connThreadLocal.set(conn);
            return conn;
        } else {
            return connThreadLocal.get();//直接返回本地变量
        }
    }

    public void  addTopic() throws SQLException{
        //从Threadlocal中获取线程对应的Connection
        Statement statement2 = getConnection().createStatement();

    }
}