android - 在Android中读取python pickle数据流

Question

我有这个包含 python pickle 数据流的文件。我必须在 Android 中读取此文件的内容。

例如，如果我想在 python 中读取这个数据流，我只需要使用下面的代码

queue = pickle.load(open('filename', 'rb'))

我想在 Android 中实现同样的事情，这样我就可以读取这个 pickle 流数据并将其存储在某种集合中。

我怎样才能做到这一点？

Answer 1

更新:这仅适用于 pickle 协议(protocol) 2 和 3。

我认为 Unpickler来自 Pyrolite 的类(class)(麻省理工学院许可证)您可能特别感兴趣。它在技术上是 Java，但 Android 基本上是 Java。要取消 pickle ，您可以执行类似于以下操作的操作:

InputStream stream = new FileInputStream("filename");
Unpickler unpickler = new Unpickler();
Object data = unpickler.load(stream);
// And cast *data* to the appropriate type.

随着导入:

import java.io.FileInputStream;
import java.io.InputStream;
import net.razorvine.pickle.Unpickler;

这些是默认支持的对象:

PYTHON    ---->     JAVA
------              ----
None                null
bool                boolean
int                 int
long                long or BigInteger  (depending on size)
string              String
unicode             String
complex             net.razorvine.pickle.objects.ComplexNumber
datetime.date       java.util.Calendar
datetime.datetime   java.util.Calendar
datetime.time       java.util.Calendar
datetime.timedelta  net.razorvine.pickle.objects.TimeDelta
float               double   (float isn't used) 
array.array         array of appropriate primitive type (char, int, short, long, float, double)
list                java.util.List<Object>
tuple               Object[]
set                 java.util.Set
dict                java.util.Map
bytes               byte[]
bytearray           byte[]
decimal             BigDecimal    
custom class        Map<String, Object>  (dict with class attributes including its name in "__class__")

另请注意:

The unpickler simply returns an Object. Because Java is a statically typed language you will have to cast that to the appropriate type. Refer to this table to see what you can expect to receive.

---

更新:我使用各种 pickle 协议(protocol) (0-3) 运行测试，发现 0 和 1 失败，但是2 和 3 成功。

这是用于生成 pickle 数据的 python 代码:

import pickle

class Data(object):
    def __init__(self):
        self.x = 12

data = Data()

for p in [0, 1, 2]:
    with open('data.{}'.format(p), 'wb') as fh:
        pickle.dump(data, fh, protocol=p)

# Python 3 only.
with open('data.3', 'wb') as fh:
    pickle.dump(data, fh, protocol=3)

以及解开它的 java 代码:

import java.io.FileInputStream;
import java.io.InputStream;
import java.io.IOException;
import java.util.Map;
import net.razorvine.pickle.Unpickler;

public class Test {
    public static void main(String[] args) throws IOException {
        String filename = args[0];
        InputStream inputStream = new FileInputStream(filename);
        Unpickler unpickler = new Unpickler();
        Map<String, Object> data = (Map<String, Object>)unpickler.load(inputStream);
    }
}

当使用 data.0 和 data.1 运行时，失败:

Exception in thread "main" net.razorvine.pickle.PickleException: expected zero arguments for construction of ClassDict (for copy_reg._reconstructor)
  at net.razorvine.pickle.objects.ClassDictConstructor.construct(ClassDictConstructor.java:23)
  at net.razorvine.pickle.Unpickler.load_reduce(Unpickler.java:617)
  at net.razorvine.pickle.Unpickler.dispatch(Unpickler.java:170)
  at net.razorvine.pickle.Unpickler.load(Unpickler.java:84)
  at Test.main(Test.java:13)

用data.2和data.3运行时，成功。