ArrayList序列化

本文链接： https://blog.csdn.net/liujunzxcv/article/details/80385741

序列化一个对象A，对象成员有一个list B，当A new A时，如果把B new 成arrayList，则会报B必须序列化的错误，这是因为arrayList的elementData 已经用transient 注解为不序列化了，解决方法是不用new arrayList填充B，比如用convert工具类转换，（用的是Spring工具类beanutils的convert方法），或者把B实现序列化接口serializable

public class A implements Serializable {
    public List<B> list;
    public Integer c;

}

public class B  implements Serializable {
    Integer b;
}

 public static void main(String[] args) {
        A a = new A();
        a.list = new ArrayList<B>();
        B b = new B();
        b.b = 1;
        a.list.add(b);
        a.c = 1;
        File file = new File("D:\\test.txt");
        FileOutputStream out;
        try {
            out = new FileOutputStream(file);
            ObjectOutputStream objOut=new ObjectOutputStream(out);
            objOut.writeObject(a);
            objOut.flush();
            objOut.close();
            System.out.println("write object success!");
            System.out.println("a.list.size:" + a.list.size());
            System.out.println("a.list.get(0):" + a.list.get(0).b);
            System.out.println("a.b:" + a.c);
        } catch (IOException e) {
            System.out.println("write object failed");
            e.printStackTrace();
        }

        try {
            FileInputStream in = new FileInputStream(file);
            ObjectInputStream objIn = new ObjectInputStream(in);
            Object temp = objIn.readObject();
            objIn.close();
            System.out.println("read object success!");
            a = (A) temp;
            System.out.println("a.list.size:" + a.list.size());
            System.out.println("a.list.get(0):" + a.list.get(0).b);
            System.out.println("a.c:" + a.c);
        } catch (IOException e) {
            System.out.println("read object failed");
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

如果B实现了序列化，写到文件再读文件都能够成功

write object success!
a.list.size:1
a.list.get(0):1
a.b:1
read object success!
a.list.size:1
a.list.get(0):1
a.c:1

如果将B取消序列化，则在写文件时会抛出异常
java.io.NotSerializableException: com.etoak.crawl.main.B
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1184)

public class B {
    Integer b;
}

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