JDBC的CRUD操作之PreparedStatement的查询操作

@Test
  /**
   * 查询操作
   */
  public void demo4(){
    Connection conn = null;
    PreparedStatement pstmt = null;
    ResultSet rs = null;
    try{
      // 获得连接:
      conn = JDBCUtils.getConnection();
      // 编写SQL:
      String sql = "select * from user";
      // 预编译SQL:
      pstmt = conn.prepareStatement(sql);
      // 设置参数:
      // 执行SQL:
      rs = pstmt.executeQuery();
      // 遍历结果集:
      while(rs.next()){
        System.out.println(rs.getInt("id")+" "+rs.getString("username")+" "+rs.getString("password")+" "+rs.getString("nickname"));
      }
    }catch(Exception e){
      e.printStackTrace();
    }finally{
      JDBCUtils.release(rs, pstmt, conn);
    }
  }