ObjectInputStream及其相關知識

一、對象的序列化和反序列化

1、對象的序列化和反序列化

/** * 將對象序列化到文件中 * * @param obj 對象 * @param file 文件 * @throws IOException IO異常 */public static void writeObjectToFile(Object obj, File file) throws IOException {    try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file))) {        oos.writeObject(obj);    }}/** * 從文件中反序列化得到對象 * * @param file 文件 * @param   對象類型 * @return 反序列化得到的對象 * @throws IOException            IO異常 * @throws ClassNotFoundException 找不到類異常 */public static  T readObjectFromFile(File file) throws IOException, ClassNotFoundException {    try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file))) {        return (T) ois.readObject();    }}

2、對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類的詳解

1、ObjectInputStream類簡介

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類的方法

/** *從流中讀取一個Object對象 * * @throws IOException            IO異常 * @throws ClassNotFoundException 找不到類異常 */public final Object readObject() throws IOException, ClassNotFoundException { /* more code */ }/** * 從流中讀取一個boolean類型的值 * * @throws IOException IO異常 */public boolean readBoolean() throws IOException { /* more code */ } 

三、ObjectOutputStream類及其相關類的詳解

1、ObjectOutputStream類簡介

public class ObjectOutputStream extends OutputStream implements ObjectOutput, ObjectStreamConstants {    /** 寫入對象 */    public void writeObject(Object obj) throws IOException {...}    /** 獲取包含此流中的所有對象曾經的引用 */    protected ObjectStreamClass getObjectStreamClass(Class cl) throws IOException, ClassNotFoundException {...}    /** 寫入單個字節 */    public void write(int val) throws IOException {...}    /** 實現數據寫入底層的操作系統 */    public void flush() throws IOException {...}    /** 關閉對象輸出流 */    public void close() throws IOException {...}}final class BlockDataOutputStream {...}final class BlockDataInputStream {...}

2、ObjectOutputStream類的方法

/** * 將指定的基本類型寫入流中。 */public final void writeInt(int val) throws IOException { /* more code */ }/** * 將單個double精度浮點數寫入流中 */public final void writeDouble(double val) throws IOException { /* more code */ }/** * 寫入一個UTF-8編碼格式的字符串 */public final void writeUTF(String str) throws IOException { /* more code */ }

四、常用工具類的使用

1、IOUtils類

/** * 將InputStream轉為byte[] * * @param inputStream 輸入流 * @return byte[] * @throws IOException IO異常 */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類

/** * 將序列化字節數組轉為指定類型的對象 * * @param bytes 序列化字節數組 * @param clazz 指定類型 * @param    類型 * @return 對象 * @throws IOException            IO異常 * @throws ClassNotFoundException 找不到類異常 */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();    }}/** * 將對象序列化為字節數組 * * @param obj 對象 * @return 序列化字節數組 * @throws IOException IO異常 */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、總結

本文主要介紹了對象的序列化和反序列化知識及其相關類，同時也介紹了常用工具類的使用。通過學習，我們了解了對象的序列化和反序列化的原理和方法，了解了ObjectInputStream、ObjectOutputStream、BlockDataOutputStream、BlockDataInputStream等相關類的詳細信息，以及IOUtils和ByteArrayUtils這兩個常用的工具類的使用方法。希望對你的學習和工作有所幫助。