ObjectInputStream及其相关知识

一、对象的序列化和反序列化

1、对象的序列化和反序列化

/** * 将对象序列化到文件中 * * @param obj 对象 * @param file 文件 * @throws IOException IO异常 */public static void writeObjectToFile(Object obj, File file) throws IOException {    try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file))) {        oos.writeObject(obj);    }}/** * 从文件中反序列化得到对象 * * @param file 文件 * @param   对象类型 * @return 反序列化得到的对象 * @throws IOException            IO异常 * @throws ClassNotFoundException 找不到类异常 */public static  T readObjectFromFile(File file) throws IOException, ClassNotFoundException {    try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file))) {        return (T) ois.readObject();    }}

2、对象的序列化和反序列化例子

public class SerializeObject {    public static void main(String[] args) throws IOException, ClassNotFoundException {        File file = new File("object.txt");        Student studentSrc = new Student("Tom", 18);        writeObjectToFile(studentSrc, file);        Student studentDst = readObjectFromFile(file);        System.out.println("studentDst = " + studentDst);    }}class Student implements Serializable {    private String name;    private int age;    public Student(String name, int age) {        this.name = name;        this.age = age;    }    @Override    public String toString() {        return "Student{" +                "name='" + name + '\'' +                ", age=" + age +                '}';    }}

二、ObjectInputStream类的详解

1、ObjectInputStream类简介

public class ObjectInputStream extends InputStream implements ObjectInput, ObjectStreamConstants {    protected ObjectInputStream() throws IOException, SecurityException {}    public ObjectInputStream(InputStream in) throws IOException {        verifySubclass();        bin = new BlockDataInputStream(in);        handles = new HandleTable(10);        vlist = new ValidationList();    }    private final BlockDataInput bin;    // more code omitted}

2、ObjectInputStream类的方法

/** *从流中读取一个Object对象 * * @throws IOException            IO异常 * @throws ClassNotFoundException 找不到类异常 */public final Object readObject() throws IOException, ClassNotFoundException { /* more code */ }/** * 从流中读取一个boolean类型的值 * * @throws IOException IO异常 */public boolean readBoolean() throws IOException { /* more code */ } 

三、ObjectOutputStream类及其相关类的详解

1、ObjectOutputStream类简介

public class ObjectOutputStream extends OutputStream implements ObjectOutput, ObjectStreamConstants {    /** 写入对象 */    public void writeObject(Object obj) throws IOException {...}    /** 获取包含此流中的所有对象曾经的引用 */    protected ObjectStreamClass getObjectStreamClass(Class cl) throws IOException, ClassNotFoundException {...}    /** 写入单个字节 */    public void write(int val) throws IOException {...}    /** 实现数据写入底层的操作系统 */    public void flush() throws IOException {...}    /** 关闭对象输出流 */    public void close() throws IOException {...}}final class BlockDataOutputStream {...}final class BlockDataInputStream {...}

2、ObjectOutputStream类的方法

/** * 将指定的基本类型写入流中。 */public final void writeInt(int val) throws IOException { /* more code */ }/** * 将单个double精度浮点数写入流中 */public final void writeDouble(double val) throws IOException { /* more code */ }/** * 写入一个UTF-8编码格式的字符串 */public final void writeUTF(String str) throws IOException { /* more code */ }

四、常用工具类的使用

1、IOUtils类

/** * 将InputStream转为byte[] * * @param inputStream 输入流 * @return byte[] * @throws IOException IO异常 */public static byte[] toByteArray(InputStream inputStream) throws IOException {    ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();    byte[] buffer = new byte[1024 * 4];    int n;    while (-1 != (n = inputStream.read(buffer))) {        byteArrayOutputStream.write(buffer, 0, n);    }    return byteArrayOutputStream.toByteArray();}

2、ByteArrayUtils类

/** * 将序列化字节数组转为指定类型的对象 * * @param bytes 序列化字节数组 * @param clazz 指定类型 * @param    类型 * @return 对象 * @throws IOException            IO异常 * @throws ClassNotFoundException 找不到类异常 */public static  T deserialize(byte[] bytes, Class clazz) throws IOException, ClassNotFoundException {    try (ByteArrayInputStream bis = new ByteArrayInputStream(bytes);         ObjectInputStream ois = new ObjectInputStream(bis)) {        return (T) ois.readObject();    }}/** * 将对象序列化为字节数组 * * @param obj 对象 * @return 序列化字节数组 * @throws IOException IO异常 */public static byte[] serialize(Object obj) throws IOException {    try (ByteArrayOutputStream bos = new ByteArrayOutputStream();         ObjectOutputStream oos = new ObjectOutputStream(bos)) {        oos.writeObject(obj);        return bos.toByteArray();    }}

五、总结

本文主要介绍了对象的序列化和反序列化知识及其相关类，同时也介绍了常用工具类的使用。通过学习，我们了解了对象的序列化和反序列化的原理和方法，了解了ObjectInputStream、ObjectOutputStream、BlockDataOutputStream、BlockDataInputStream等相关类的详细信息，以及IOUtils和ByteArrayUtils这两个常用的工具类的使用方法。希望对你的学习和工作有所帮助。