Java四种拷贝方式实战总结(一文扫清所有拷贝问题)

class Address {
    String city;
}

class Person {
    String name;
    Address address;

    // 浅拷贝
    Person shallowCopy() {
        Person copy = new Person();
        copy.name = this.name;
        copy.address = this.address;
        return copy;
    }

    // 深拷贝
    Person deepCopy() {
        Person copy = new Person();
        copy.name = this.name;
        copy.address = new Address();
        copy.address.city = this.address.city;
        return copy;
    }
}

// 传统IO方式，适合小文件
public static void copyFileByIO(File source, File dest) throws IOException {
    try (InputStream is = new FileInputStream(source);
         OutputStream os = new FileOutputStream(dest)) {
        byte[] buffer = new byte[1024];
        int len;
        while ((len = is.read(buffer)) != -1) {
            os.write(buffer, 0, len);
        }
    }
}

// NIO方式，适合大文件
public static void copyFileByNIO(File source, File dest) throws IOException {
    try (FileChannel sourceChannel = new FileInputStream(source).getChannel();
         FileChannel destChannel = new FileOutputStream(dest).getChannel()) {
        destChannel.transferFrom(sourceChannel, 0, sourceChannel.size());
    }
}

public static <T extends Serializable> T deepCopyBySerialization(T obj) {
    try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
         ObjectOutputStream oos = new ObjectOutputStream(baos)) {
        oos.writeObject(obj);
        try (ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
             ObjectInputStream ois = new ObjectInputStream(bais)) {
            return (T) ois.readObject();
        }
    } catch (IOException | ClassNotFoundException e) {
        throw new RuntimeException(e);
    }
}

import com.fasterxml.jackson.databind.ObjectMapper;

public static <T> T deepCopyByJSON(T obj, Class<T> clazz) {
    try {
        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(obj);
        return mapper.readValue(json, clazz);
    } catch (Exception e) {
        throw new RuntimeException(e);
    }
}

int[] intArray = {1, 2, 3};
int[] copiedIntArray = intArray.clone(); // 深拷贝

Person[] personArray = new Person[2];
Person[] copiedPersonArray = personArray.clone(); // 浅拷贝

List<Person> originalList = new ArrayList<>();
List<Person> deepCopiedList = originalList.stream()
        .map(Person::deepCopy)
        .collect(Collectors.toList());

<!-- Apache Commons Lang依赖 -->
<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.12.0</version>
</dependency>

// 使用示例
Person copiedPerson = SerializationUtils.clone(originalPerson);