JDBC自定义连接池过程详解

DataSourcePool

public class DataSourcePool implements DataSource {
  //1.创建1个容器用于存储Connection对象
  private static LinkedList<Connection> pool = new LinkedList<Connection>();

  //2.创建5个连接放到容器中去
  static{
    for (int i = 0; i < 5; i++) {
      Connection conn = JDBCUtils.getConnection();
      //放入池子中connection对象已经经过改造了
      ConnectionPool connectionPool = new ConnectionPool(conn, pool);
      pool.add(connectionPool);
    }
  }

  /**
   * 重写获取连接的方法
   */
  @Override
  public Connection getConnection() throws SQLException {
    Connection conn = null;
    //3.使用前先判断
    if(pool.size()==0){
      //4.池子里面没有，我们再创建一些
      for (int i = 0; i < 5; i++) {
        conn = JDBCUtils.getConnection();
        //放入池子中connection对象已经经过改造了
        ConnectionPool connectionPool = new ConnectionPool(conn, pool);
        pool.add(connectionPool);
      }
    }
    //5.从池子里面获取一个连接对象Connection
    conn = pool.remove(0);
    return conn;
  }


  @Override
  public Connection getConnection(String username, String password) throws SQLException {
    return null;
  }

  @Override
  public <T> T unwrap(Class<T> iface) throws SQLException {
    return null;
  }

  @Override
  public boolean isWrapperFor(Class<?> iface) throws SQLException {
    return false;
  }

  @Override
  public PrintWriter getLogWriter() throws SQLException {
    return null;
  }

  @Override
  public void setLogWriter(PrintWriter out) throws SQLException {

  }

  @Override
  public void setLoginTimeout(int seconds) throws SQLException {

  }

  @Override
  public int getLoginTimeout() throws SQLException {
    return 0;
  }

  @Override
  public Logger getParentLogger() throws SQLFeatureNotSupportedException {
    return null;
  }
}

测试代码如下

 @Test
  public void test1(){
    Connection conn = null;
    PreparedStatement pstmt = null;
    // 1.创建自定义连接池对象
    DataSource dataSource = new DataSourcePool();
    try {
      // 2.从池子中获取连接
      conn = dataSource.getConnection();
      String sql = "insert into USER values(?,?)";
      //3.必须在自定义的connection类中重写prepareStatement(sql)方法
      pstmt = conn.prepareStatement(sql);
      pstmt.setString(1, "李四");
      pstmt.setString(2, "1234");
      int rows = pstmt.executeUpdate();
      System.out.println("rows:"+rows);
    } catch (Exception e) {
      throw new RuntimeException(e);
    } finally {
      JDBCUtils.relase(conn, pstmt, null);
    }
  }

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