java jdbc娣卞叆鐞嗚В锛坈onnection涓巘hreadlocal涓庢暟鎹簱杩炴帴姹犲拰浜嬪姟瀹烇級

Posted 2020-11-28

鏍囩锛?a href='http://www.mamicode.com/so/1/i_1__1_' title='i++'>i++   ==   session   tac   throws   keep   涓婁笅   timeout   name   

1.jdbc杩炴帴鏁版嵁搴擄紝灏辫繖鏍峰瓙

Class.forName("com.mysql.jdbc.Driver");
java.sql.Connection conn = DriverManager.getConnection(jdbcUrl);

2.閫氳繃浼犲叆jdbc url鐢―rivermanager.getConnection(jdbcurl)杩炴帴鏁版嵁搴擄紝

娉ㄦ剰锛氫竴娆rivermanager.getConnection(jdbcurl)鑾峰緱鍙槸涓€涓猚onnection锛屽苟涓嶈兘婊¤冻楂樺苟鍙戞儏鍐点€傚洜涓篶onnection涓嶆槸绾跨▼瀹夊叏鐨勶紝涓€涓猚onnection瀵瑰簲鐨勬槸涓€涓簨鐗┿€?/p>

3.鎵€浠ユ暟鎹簱杩炴帴姹狅紝鏄娆rivermanager.getConnection(jdbcurl)锛岃幏鍙栧涓猚onnection鏀惧叆hashmap涓€?/p>

4.姣忔鑾峰緱connection閮介渶瑕佹氮璐筩pu璧勬簮鍜屽唴瀛樿祫婧愶紝鏄緢娴垂璧勬簮鐨勩€傛墍浠ヨ癁鐢熶簡鏁版嵁搴撹繛鎺ユ睜銆?/p>

5.鏁版嵁搴撹繛鎺ユ睜閮ㄥ垎婧愮爜锛?/p>

娉ㄦ剰pool.getConnection()锛岄兘鏄厛浠巘hreadlocal閲岄潰鎷跨殑锛屽鏋渢hreadlocal閲岄潰鏈夛紝鍒欑敤锛屼繚璇佺嚎绋嬮噷鐨勫涓猟ao鎿嶄綔锛岀敤鐨勬槸鍚屼竴涓猚onnection锛屼互淇濊瘉浜嬪姟銆?/p>

濡傛灉鏂扮嚎绋嬶紝鍒欏皢鏂扮殑connection鏀惧湪threadlocal閲岋紝鍐峠et缁欏埌绾跨▼銆?/p>

鐫€閲嶇湅浠ヤ笅鍑犱釜鏂规硶锛岃鏄庢暟鎹簱杩炴帴姹狅紝鏄皢connection鏀捐繘threadlocal閲岀殑锛屼互淇濊瘉姣忎釜绾跨▼浠庤繛鎺ユ睜涓幏寰楃殑閮芥槸绾跨▼鑷繁鐨刢onnection銆?/p>

 

1.  // 灏嗙嚎绋嬪拰杩炴帴缁戝畾锛屼繚璇佷簨鍔¤兘缁熶竴鎵ц  
2.  鎴愬憳鍙橀噺   private static ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>(); 

 // 鑾峰緱褰撳墠杩炴帴  
    public Connection getCurrentConnecton(){  
        // 榛樿绾跨▼閲岄潰鍙? 
        Connection conn = threadLocal.get();  
        if(!isValid(conn)){  
            conn = getConnection();  
        }  
        return conn;  
    }  

// 鑾峰緱杩炴帴  
    public synchronized Connection getConnection() {  
        Connection conn = null;  
        try {  
            // 鍒ゆ柇鏄惁瓒呰繃鏈€澶ц繛鎺ユ暟闄愬埗  
            if(contActive < this.dbBean.getMaxActiveConnections()){  
                if (freeConnection.size() > 0) {  
                    conn = freeConnection.get(0);  
                    if (conn != null) {  
                        threadLocal.set(conn);  
                    }  
                    freeConnection.remove(0);  
                } else {  
                    conn = newConnection();  
                }  
                  
            }else{  
                // 缁х画鑾峰緱杩炴帴,鐩村埌浠庢柊鑾峰緱杩炴帴  
                wait(this.dbBean.getConnTimeOut());  
                conn = getConnection();  
            }  
            if (isValid(conn)) {  
                activeConnection.add(conn);  
                contActive ++;  
            }  
        } catch (SQLException e) {  
            e.printStackTrace();  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        } catch (InterruptedException e) {  
            e.printStackTrace();  
        }  
        return conn;  
    }

public synchronized void releaseConn(Connection conn) throws SQLException {  
        if (isValid(conn)&& !(freeConnection.size() > dbBean.getMaxConnections())) {  
            freeConnection.add(conn);  
            activeConnection.remove(conn);  
            contActive --;  
            threadLocal.remove();  
            // 鍞ら啋鎵€鏈夋寰呯瓑寰呯殑绾跨▼锛屽幓鎶㈣繛鎺? 
            notifyAll();  
        }  
    } 

鐒跺悗鍐嶇潃閲嶇悊瑙ｆ娈佃瘽

棣栧厛,LZ鏄蹇典笂鐨勯敊璇?浠€涔堟槸绾跨▼姹?浠€涔堟槸ThreadLocal???
   绾跨▼姹?涓洪伩鍏嶄笉蹇呰鐨勫垱寤?閿€姣乧onnection鑰屽瓨鍦ㄧ殑,鍏朵腑鍖呮嫭娲诲姩,绛夊緟,鏈€灏忕瓑灞炴€?cop3,proxy杩炴帴姹犻兘鍙互閰嶇疆杩欎簺鐜╂剰;
   
   鑷充簬涓轰粈涔堣鐢═hreadLocal鍛?杩欎釜鍜岃繛鎺ユ睜鏃犲叧,鎴戣涓烘洿澶氱殑鏄拰绋嬪簭鏈韩鐩稿叧,涓轰簡鏇存竻妤氱殑璇存槑,鎴戜妇涓緥瀛?   servlet涓幏鍙栦竴涓繛鎺?棣栧厛,servlet鏄嚎绋嬪畨鍏ㄧ殑鍚?
     class MyServlet extends HttpServlet{
         private Connection conn;
     }
     ok,閬楁喚鐨勫憡璇変綘,杩欎釜conn骞朵笉鏄畨鍏ㄧ殑,鎵€鏈夎姹傝繖涓猻ervlet鐨勮繛鎺?浣跨敤鐨勯兘鏄竴涓狢onnection,杩欎釜灏辨槸鑷村懡鐨勪簡.澶氫釜浜轰娇鐢ㄥ悓涓€涓繛鎺?绠椾笂寤惰繜鍟ョ殑,澶╃煡閬撴暟鎹細鎴愪粈涔堟牱.
     鍥犳鎴戜滑瑕佷繚璇丆onnection瀵规瘡涓姹傞兘鏄敮涓€鐨?杩欎釜鏃跺€欏氨鍙互鐢ㄥ埌ThreadLocal浜?淇濊瘉姣忎釜绾跨▼閮芥湁鑷繁鐨勮繛鎺?
     鏀逛负 private ThreadLocal<Connection> ct = new ThreadLocal<Connnection>();
     鐒跺悗浠庤繛鎺ユ睜鑾峰彇Connection,set鍒癱t涓?鍐峠et灏辫浜?鑷充簬寰楀埌鐨勬槸鍝釜Connection灏辨槸杩炴帴姹犵殑闂浜?浣犱篃绠′笉鍒?

 

Hibernate鐨勬暟鎹簱杩炴帴姹犲氨鏄皢connection鏀捐繘threadlocal瀹炵幇鐨勶紒锛侊紒

Hibernate鐨勬暟鎹簱杩炴帴姹犲氨鏄皢connection鏀捐繘threadlocal瀹炵幇鐨勶紒锛侊紒

Hibernate鐨勬暟鎹簱杩炴帴姹犲氨鏄皢connection鏀捐繘threadlocal瀹炵幇鐨勶紒锛侊紒

public class ConnectionPool implements IConnectionPool {  
    // 杩炴帴姹犻厤缃睘鎬? 
    private DBbean dbBean;  
    private boolean isActive = false; // 杩炴帴姹犳椿鍔ㄧ姸鎬? 
    private int contActive = 0;// 璁板綍鍒涘缓鐨勬€荤殑杩炴帴鏁? 
      
    // 绌洪棽杩炴帴  
    private List<Connection> freeConnection = new Vector<Connection>();  
    // 娲诲姩杩炴帴  
    private List<Connection> activeConnection = new Vector<Connection>();  
  

1.  // 灏嗙嚎绋嬪拰杩炴帴缁戝畾锛屼繚璇佷簨鍔¤兘缁熶竴鎵ц
2.     private static ThreadLocal<Connection> threadLocal = new ThreadLocal<Connection>(); 

public ConnectionPool(DBbean dbBean) {  
        super();  
        this.dbBean = dbBean;  
        init();  
        cheackPool();  
    }  
  
    // 鍒濆鍖? 
    public void init() {  
        try {  
            Class.forName(dbBean.getDriverName());  
            for (int i = 0; i < dbBean.getInitConnections(); i++) {  
                Connection conn;  
                conn = newConnection();  
                // 鍒濆鍖栨渶灏忚繛鎺ユ暟  
                if (conn != null) {  
                    freeConnection.add(conn);  
                    contActive++;  
                }  
            }  
            isActive = true;  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        } catch (SQLException e) {  
            e.printStackTrace();  
        }  
    }  
      
    // 鑾峰緱褰撳墠杩炴帴  
    public Connection getCurrentConnecton(){  
        // 榛樿绾跨▼閲岄潰鍙? 
        Connection conn = threadLocal.get();  
        if(!isValid(conn)){  
            conn = getConnection();  
        }  
        return conn;  
    }  
  
    // 鑾峰緱杩炴帴  
    public synchronized Connection getConnection() {  
        Connection conn = null;  
        try {  
            // 鍒ゆ柇鏄惁瓒呰繃鏈€澶ц繛鎺ユ暟闄愬埗  
            if(contActive < this.dbBean.getMaxActiveConnections()){  
                if (freeConnection.size() > 0) {  
                    conn = freeConnection.get(0);  
                    if (conn != null) {  
                        threadLocal.set(conn);  
                    }  
                    freeConnection.remove(0);  
                } else {  
                    conn = newConnection();  
                }  
                  
            }else{  
                // 缁х画鑾峰緱杩炴帴,鐩村埌浠庢柊鑾峰緱杩炴帴  
                wait(this.dbBean.getConnTimeOut());  
                conn = getConnection();  
            }  
            if (isValid(conn)) {  
                activeConnection.add(conn);  
                contActive ++;  
            }  
        } catch (SQLException e) {  
            e.printStackTrace();  
        } catch (ClassNotFoundException e) {  
            e.printStackTrace();  
        } catch (InterruptedException e) {  
            e.printStackTrace();  
        }  
        return conn;  
    }  
  
    // 鑾峰緱鏂拌繛鎺? 
    private synchronized Connection newConnection()  
            throws ClassNotFoundException, SQLException {  
        Connection conn = null;  
        if (dbBean != null) {  
            Class.forName(dbBean.getDriverName());  
            conn = DriverManager.getConnection(dbBean.getUrl(),  
                    dbBean.getUserName(), dbBean.getPassword());  
        }  
        return conn;  
    }  
  
    // 閲婃斁杩炴帴  
    public synchronized void releaseConn(Connection conn) throws SQLException {  
        if (isValid(conn)&& !(freeConnection.size() > dbBean.getMaxConnections())) {  
            freeConnection.add(conn);  
            activeConnection.remove(conn);  
            contActive --;  
            threadLocal.remove();  
            // 鍞ら啋鎵€鏈夋寰呯瓑寰呯殑绾跨▼锛屽幓鎶㈣繛鎺? 
            notifyAll();  
        }  
    }  
  
    // 鍒ゆ柇杩炴帴鏄惁鍙敤  
    private boolean isValid(Connection conn) {  
        try {  
            if (conn == null || conn.isClosed()) {  
                return false;  
            }  
        } catch (SQLException e) {  
            e.printStackTrace();  
        }  
        return true;  
    }  
  
    // 閿€姣佽繛鎺ユ睜  
    public synchronized void destroy() {  
        for (Connection conn : freeConnection) {  
            try {  
                if (isValid(conn)) {  
                    conn.close();  
                }  
            } catch (SQLException e) {  
                e.printStackTrace();  
            }  
        }  
        for (Connection conn : activeConnection) {  
            try {  
                if (isValid(conn)) {  
                    conn.close();  
                }  
            } catch (SQLException e) {  
                e.printStackTrace();  
            }  
        }  
        isActive = false;  
        contActive = 0;  
    }  
  
    // 杩炴帴姹犵姸鎬? 
    @Override  
    public boolean isActive() {  
        return isActive;  
    }  
      
    // 瀹氭椂妫€鏌ヨ繛鎺ユ睜鎯呭喌  
    @Override  
    public void cheackPool() {  
        if(dbBean.isCheakPool()){  
            new Timer().schedule(new TimerTask() {  
            @Override  
            public void run() {  
            // 1.瀵圭嚎绋嬮噷闈㈢殑杩炴帴鐘舵€? 
            // 2.杩炴帴姹犳渶灏?鏈€澶ц繛鎺ユ暟  
            // 3.鍏朵粬鐘舵€佽繘琛屾鏌ワ紝鍥犱负杩欓噷杩橀渶瑕佸啓鍑犱釜绾跨▼绠＄悊鐨勭被锛屾殏鏃跺氨涓嶆坊鍔犱簡  
            System.out.println("绌虹嚎姹犺繛鎺ユ暟锛?+freeConnection.size());  
            System.out.println("娲诲姩杩炴帴鏁帮細锛?+activeConnection.size());  
            System.out.println("鎬荤殑杩炴帴鏁帮細"+contActive);  
                }  
            },dbBean.getLazyCheck(),dbBean.getPeriodCheck());  
        }  
    }  
}  

 

Why ThreadLocal?

鏃犺濡備綍锛岃缂栧啓涓€涓绾跨▼瀹夊叏(Thread-safe)鐨勭▼搴忔槸鍥伴毦鐨勶紝涓轰簡璁╃嚎绋嬪叡浜祫婧愶紝蹇呴』灏忓績鍦板鍏变韩璧勬簮杩涜鍚屾锛屽悓姝ュ甫鏉ヤ竴瀹氱殑鏁堣兘寤惰繜锛岃€屽彟涓€鏂归潰锛屽湪澶勭悊鍚屾鐨勬椂鍊欙紝鍙堣娉ㄦ剰瀵硅薄鐨勯攣瀹氫笌閲婃斁锛岄伩鍏嶄骇鐢熸缁擄紝绉嶇鍥犵礌閮戒娇寰楃紪鍐欏绾跨▼绋嬪簭鍙樺緱鍥伴毦銆?/p>

灏濊瘯浠庡彟涓€涓搴︽潵鎬濊€冨绾跨▼鍏变韩璧勬簮鐨勯棶棰橈紝鏃㈢劧鍏变韩璧勬簮杩欎箞鍥伴毦锛岄偅涔堝氨骞茶剢涓嶈鍏变韩锛屼綍涓嶄负姣忎釜绾跨▼鍒涢€犱竴涓祫婧愮殑澶嶆湰銆傚皢姣忎竴涓嚎绋嬪瓨鍙栨暟鎹殑琛屼负鍔犱互闅旂锛屽疄鐜扮殑鏂规硶灏辨槸缁欎簣姣忎釜绾跨▼涓€涓壒瀹氱┖闂存潵淇濈璇ョ嚎绋嬫墍鐙韩鐨勮祫婧?/p>

 

浠€涔堟槸ThreadLocal锛?/strong>