我有一些关于在JSP Web应用程序中使用Hibernate的问题.
应该是什么价值hibernate.current_session_context_class？
那么,应该使用以下哪个陈述？为什么？
Session s = HibernateUtil.getSessionFactory().openSession();
Session s = HibernateUtil.getSessionFactory().getCurrentSession()
最后,哪一个更好"每个网络应用一个会话"或"每个请求一个会话"？
我正在使用Hibernate来持久化这个bean.
import javax.persistence.*;
@Entity
public class Person {
@Id @GeneratedValue
private int id;
@Column
private String name;
@OneToOne
private Address addr;
}
有什么CascadeType用addr？
我可以Dense使用keras.datasets.fashion_mnist数据集训练带有图层的Keras网络.但是,当我尝试训练卷积网络时,我收到了一个错误.
以下是代码的一部分:
from tensorflow.keras.layers import *
model = keras.Sequential([
Convolution2D(16, (3,3), activation='relu', input_shape=(28,28,1)),
MaxPooling2D(pool_size=(2,2)),
Flatten(),
Dense(16, activation='relu'),
Dense(10, activation='softmax')
])
model.compile(optimizer=tf.train.AdamOptimizer(),
loss='sparse_categorical_crossentropy',
metrics=['accuracy'])
model.fit(train_images, train_labels, epochs=5)
当我试图适应时它的错误.
UnknownError:无法获得卷积算法.这可能是因为cuDNN无法初始化,因此请尝试查看上面是否打印了警告日志消息.[[{{node conv2d/Conv2D}} = Conv2D [T = DT_FLOAT,data_format ="NCHW",dilations = [1,1,1,1],padding ="VALID",strides = [1,1,1, 1],use_cudnn_on_gpu = true,_device ="/ job:localhost/replica:0/task:0/device:GPU:0"](training/TFOptimizer/gradients/conv2d/Conv2D_grad/Conv2DBackpropFilter-0-TransposeNHWCToNCHW-LayoutOptimizer,conv2d/Conv2D/ReadVariableOp)]] [[{{node loss/dense_1_loss/broadcast_weights/assert_broadcastable/AssertGuard/Assert/Switch_2/_69}} = _Recvclient_terminated = false,recv_device ="/ job:localhost/replica:0/task:0/device:CPU:0",send_device ="/ job:localhost/replica:0/task:0/device:GPU:0",send_device_incarnation = 1,tensor_name ="edge_112_l ... t/Switch_2",tensor_type = DT_INT32, _device = "/作业:本地主机/复制:0 /任务:0 /装置:CPU:0"]]
我有cudnn64_7.dll,C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v9.0\bin并且 …
我有关于旋转Android设备的问题.我的代码在onCreate(...)中记录了一个静态和非静态属性.
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
public class MainActivity extends Activity {
static int sn;
int n;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
sn++;
n++;
Log.i("onCreate", String.format("sn=%d n=%d", sn, n));
}
}
屏幕方向是纵向.当我第一次运行代码时,我得到了:
onCreate(): sn=1 n=1
在我将屏幕旋转到风景后,我得到了:
onCreate(): sn=2 n=1
在我再次将屏幕旋转为肖像后,我得到了:
onCreate(): sn=3 n=1
onCreate(): sn=4 n=1
我的问题是:
我正在使用PySpark 1.5.2.我UserWarning Please install psutil to have better support with spilling发出命令后得到了.collect()
为什么会出现此警告？
我该如何安装psutil？
我认为C中的局部变量没有初始化.但是当我用gcc编译这段代码时.
void f() {
static int s;
int n;
printf("static s = %d\n", s++);
printf("local n = %d\n", n++);
f();
}
main() {
f();
}
并运行此代码,部分结果是:
static s = 0
local n = 0
static s = 1
local n = 0
static s = 2
local n = 0
static s = 3
local n = 0
static s = 4
local n = 0
static s = 5
local n = 0
...
static s = 261974
local …我想知道从 super() 函数获得的实例的类型。我试着print(super())和__print(type(super()))__
class Base:
def __init__(self):
pass
class Derive(Base):
def __init__(self):
print(super())
print(type(super()))
super().__init__()
d = Derive()
结果是
<super: <class 'Derive'>, <Derive object>>
<class 'super'>
有了这些结果，我想知道如何super().__init__()调用正确的构造函数。
我尝试使用Python Tkinter创建一个模态对话框.我发现使用和不使用wait_window()之间没有区别.
import tkinter as tk
def button_click():
dlg = tk.Toplevel(master=window)
tk.Button(dlg, text="Dismiss", command=dlg.destroy).pack()
dlg.transient(window) # only one window in the task bar
dlg.grab_set() # modal
#window.wait_window(dlg) # why?
window = tk.Tk()
tk.Button(window, text="Click Me", command=button_click).pack()
window.mainloop()
我已经看到了一些使用wait_window()来创建模态对话框的例子.所以我不确定是否需要该函数来创建模态对话框.
我正在使用Python 3.5.
我正在尝试编写一个返回列表中第一项的Haskell函数.
h [] = Nothing
h (x:xs) = x
当我用空列表调用它时:
main = print (h [])
我收到以下错误:
prog.hs:4:8:
No instance for (Show a0) arising from a use of `print'
The type variable `a0' is ambiguous
Possible fix: add a type signature that fixes these type variable(s)
Note: there are several potential instances:
instance Show Double -- Defined in `GHC.Float'
instance Show Float -- Defined in `GHC.Float'
instance (Integral a, Show a) => Show (GHC.Real.Ratio a)
-- Defined in `GHC.Real'
...plus 23 …以下两个代码都给出了相同的结果.但我不知道我应该在哪里提出加注声明.
def bisection(f, start, stop, eps = 1e-5, max_iteration = 100):
for __ in range(max_iteration):
half = start + (stop - start)/2
if abs(f(half)) < eps or half - start < eps:
return half
if f(half) * f(start) > 0:
start = half
else:
stop = half
else:
raise ValueError('Cannot find root in the given range')
要么
def bisection(f, start, stop, eps = 1e-5, max_iteration = 100):
for __ in range(max_iteration):
half = start + (stop - start)/2 …我想转换以下字符串:
s = '1|2|a|b'
至
[1, 2, 'a', 'b']
是否可以在一行中进行转换？
我创建了一个带有两个按钮的窗口,并设置了两个按钮的填充.
from tkinter import *
window = Tk()
Button(window, text="Click Me").pack(padx=10, pady=10)
Button(window, text="Click Me").pack(padx=10, pady=10)
window.mainloop()
我想删除padx和pady参数pack()并得到相同的结果.我怎样才能做到这一点？