java - Java中Generic Type序列化的HashMap之HashMap

Question

已修复，根据 Engineer Dollery 的回答，解决方案在底部。

目标是序列化网络类的网络字段。抱歉命名。

我有这个，可以正确编译和序列化。

public class Network {
    private HashMap<String, HashMap<String, Number>> network;
    ...
    public void load(String networkFile) throws Exception{
        network = (HashMap<String, HashMap<String, Number>>)Utility.deserialize(Utility.load(networkFile));
    }

    public void save(String networkFile) throws Exception{
        Utility.save(networkFile, Utility.serialize(network));
    }
}

class Number implements Serializable {
    ...
}

我将其更改为这个通用版本，它可以编译，但不再序列化。我需要以某种方式指定 T 和 Number 的 HashMap 是可序列化的。

public class Network<T extends Serializable> {
    private HashMap<T, HashMap<T, Number>> network;
    ...

    public void load(String networkFile) throws Exception{
        network = (HashMap<T, HashMap<T, Number>>)Utility.deserialize(Utility.load(networkFile));
    }

    public void save(String networkFile) throws Exception{
        Utility.save(networkFile, Utility.serialize(network));
    }
}

class Number implements Serializable {
    ...
}

这是序列化的代码

package Bullib;

import java.io.*;
import java.util.*;
import java.util.regex.*;

public class Utility{

    public static Pattern phrasePattern = Pattern.compile("[^;:!.?]+");
    public static Pattern wordPattern = Pattern.compile("['A-Za-z]+");

    public static Object deserialize(byte[] serialized) throws Exception {
        ByteArrayInputStream bi = new ByteArrayInputStream(serialized);
        ObjectInputStream si = new ObjectInputStream(bi);
        return si.readObject();
    }

    public static byte[] serialize(Object target) throws Exception {
        ByteArrayOutputStream bo = new ByteArrayOutputStream();
        ObjectOutputStream so = new ObjectOutputStream(bo);
        so.writeObject(target);
        so.flush();
        return bo.toByteArray();
    }

    public static byte[] load(String filename)  throws Exception {
        RandomAccessFile file = new RandomAccessFile(new File(filename), "r");
        byte[] b = new byte[(int)file.length()];
        file.read(b);
        file.close();
        return b;
    }

    public static void save(String filename, byte[] value) throws Exception {
        RandomAccessFile file = new RandomAccessFile(new File(filename), "rw");
        file.write(value);
        file.close();
    }

    public static Collection<String> executeRegex(Pattern pattern, String text){
        LinkedList<String> matches = new LinkedList<String>();
        Matcher m = pattern.matcher(text);
        while (m.find()) {
            matches.add(m.group(0));
        }
        return matches;
    }
}

这是我尝试将 T 序列化为 String 或 Double 时返回的错误

Exception in thread "main" java.io.NotSerializableException: Bullib.Network.Netw
ork
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
        at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.writeObject(Unknown Source)
        at java.util.HashMap.writeObject(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
        at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.writeObject(Unknown Source)
        at java.util.HashMap.writeObject(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
        at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.writeObject(Unknown Source)
        at Bullib.Utility.serialize(Utility.java:21)
        at Bullib.Network.Network.save(Network.java:88)
        at Engine.save(Engine.java:63)
        at Engine.main(Engine.java:88)

根据请求，示例测试和错误。如您所见，它会产生与上述相同的异常。我已经更新了测试，以表明如果没有向 map 添加任何内容，它就会通过，否则会失败。

public static void main(String[] args) throws Exception{
    Network<String> stringtest = new Network<String>("","","");
    stringtest.save("testempty");
    stringtest.load("testempty");
    System.out.println("passed empty");
    stringtest.placeAndMove("fill",0.0);
    stringtest.save("testfilled");
    stringtest.load("testfilled");
    System.out.println("passed filled");
}

java: Bullib/Network/Network
passed empty
Exception in thread "main" java.io.NotSerializableException: Bullib.Network.Netw
ork
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
        at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.writeObject(Unknown Source)
        at java.util.HashMap.writeObject(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
        at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.writeObject(Unknown Source)
        at java.util.HashMap.writeObject(Unknown Source)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at java.io.ObjectStreamClass.invokeWriteObject(Unknown Source)
        at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
        at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
        at java.io.ObjectOutputStream.writeObject0(Unknown Source)
        at java.io.ObjectOutputStream.writeObject(Unknown Source)
        at Bullib.Utility.serialize(Utility.java:21)
        at Bullib.Network.Network.save(Network.java:88)
        at Bullib.Network.Network.main(Network.java:108)

解决办法是改变

public class Network<T extends Serializable> {
    private HashMap<T, HashMap<T, Number>> network;
    ...

    public void load(String networkFile) throws Exception{
        network = (HashMap<T, HashMap<T, Number>>)Utility.deserialize(Utility.load(networkFile));
    }

    public void save(String networkFile) throws Exception{
        Utility.save(networkFile, Utility.serialize(network));
    }
}

class Number implements Serializable {
    ...
}

到

public class Network<T extends Serializable> implements Serializable {
    private HashMap<T, HashMap<T, Number>> network;
    ...

    public void load(String networkFile) throws Exception{
        network = (HashMap<T, HashMap<T, Number>>)Utility.deserialize(Utility.load(networkFile));
    }

    public void save(String networkFile) throws Exception{
        Utility.save(networkFile, Utility.serialize(network));
    }
}

class Number implements Serializable {
    ...
}

Answer 1

试试这个:

public class Network implements Serializable