Java中的可外部化接口
每当我们需要自定义序列化机制时，都会使用外部化。如果类实现了Externalizable接口，则将使用writeExternal()方法完成对象序列化。而在接收者端，当Externalizable对象是重构实例时，将不使用任何参数构造函数来创建该对象，然后readExternal()调用该方法。
如果一个类仅实现Serializable接口对象，则将使用ObjectoutputStream进行序列化。在接收者端，可序列化的对象使用ObjectInputStream进行重构。
下面的示例展示了Externalizable接口的用法。
示例
import java.io.Externalizable;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectInputStream;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
public class Tester {
public static void main(String[] args) {
Employee e = new Employee();
e.name = "Reyan Ali";
e.age = 30;
try (
FileOutputStream fileOut = new FileOutputStream("test.txt");
ObjectOutputStream out = new ObjectOutputStream(fileOut);
) {
out.writeObject(e);
}catch (IOException i) {
System.out.println(i.getMessage());
}
try (
FileInputStream fileIn = new FileInputStream("test.txt");
ObjectInputStream in = new ObjectInputStream(fileIn);
) {
e = (Employee)in.readObject();
System.out.println(e.name);
System.out.println(e.age);
} catch (IOException i) {
System.out.println(i.getMessage());
} catch (ClassNotFoundException e1) {
System.out.println(e1.getMessage());
}
}
}
class Employee implements Externalizable {
public Employee(){}
String name;
int age;
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(name);
out.writeInt(age);
}
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
name = (String)in.readObject();
age = in.readInt();
}
}这将产生以下结果-
输出结果
Reyan Ali 30