RandomAccessFile
随机访问文件，支持随机读写
- seek(long pos)绝对定位
- skipBytes(int num) 相对值
- read()
- write()
- RandomAccessFile(String str, String mode)
- r
- rw
- rws
- rwd
多线程复制文件
存储对象
流的关闭
1 import java.io.FileInputStream;
2 import java.io.FileOutputStream;
3 import java.io.ObjectInputStream;
4 import java.io.ObjectOutputStream;
5
6 import org.junit.Test;
7
8 public class ObjectSerializeDemo {
9
10 public static void main(String[] args) throws Exception {
11 //serialize();
12 //deSerialize();
13 serializePerson();
14 deSerializePerson();
15 }
16
17 /**
18 * 串行化方法
19 * @throws Exception
20 */
21 private static void serialize() throws Exception {
22 // 一个对象
23 Integer i = new Integer(100);
24 FileOutputStream fos = new FileOutputStream("h:/a.data");
25
26
27 // 通过文件输出流构造对象输出流
28 ObjectOutputStream oos = new ObjectOutputStream(fos);
29 oos.writeObject(i);
30
31 //关闭流
32
33 oos.close();
34 //fos.close();
35 System.out.println("over");
36 }
37
38 /**
39 * 反串行化方法
40 * @throws Exception
41 */
42 private static void deSerialize() throws Exception {
43 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("h:/a.data"));
44 Integer i = (Integer) ois.readObject();
45 ois.close();
46
47 System.out.println(i);
48 }
49
50 /**
51 * 串行化javabean方法
52 * @throws Exception
53 */
54 @Test
55 private static void serializePerson() throws Exception {
56 Person p = new Person("tom", 21);
57 FileOutputStream fos = new FileOutputStream("h:/p.data");
58 ObjectOutputStream oos = new ObjectOutputStream(fos);
59 oos.writeObject(p);
60 oos.close();
61 //fos.close();
62 System.out.println("over");
63 }
64
65 /**
66 * 反串行化javabean方法
67 * @throws Exception
68 */
69 private static void deSerializePerson() throws Exception {
70 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("h:/p.data"));
71 Person p = (Person) ois.readObject();
72 ois.close();
73
74 System.out.println(p.getName());
75 }
76 }
1 import java.io.Serializable;
2 // 实现对象串行化接口
3 public class Person implements Serializable{
4 private static final long serialVersionUID = -5854465328288308968L;
5 private String name;
6 private int age;
7 public Person() {
8
9 }
10 public Person(String name, int age) {
11 this.name = name;
12 this.age = age;
13 }
14 public String getName() {
15 return name;
16 }
17 public void setName(String name) {
18 this.name = name;
19 }
20 public int getAge() {
21 return age;
22 }
23 public void setAge(int age) {
24 this.age = age;
25 }
26
27 }
串行化（序列化）
将java对象转换成某种格式（JVM定义的）的字节数组
反串行化（序列化）
将字节数组恢复成java对象
java.io.Serializable
可串行接口 标志性接口
串行化应用场景
将对象用于网络间传输或本地化存储
深度复制
1 import java.io.FileInputStream;
2 import java.io.FileOutputStream;
3 import java.io.ObjectInputStream;
4 import java.io.ObjectOutputStream;
5 import java.io.Serializable;
6
7 import org.junit.Test;
8
9 /**
10 * 深度复制
11 * @author zhengguohuang
12 *
13 */
14 public class DeepCopyDemo {
15 /**
16 * 串行化过程
17 * @throws Exception
18 */
19 @Test
20 public void seria() throws Exception {
21 Person p = new Person();
22 Son s = new Son();
23 Dog d = new Dog();
24 //设置关联关系
25 s.setPerson(p);
26 d.setPerson(p);
27 d.setSon(s);
28 //串行化
29 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("h://kkk.data"));
30 oos.writeObject(d);
31 oos.close();
32 }
33
34 /**
35 * 反串行化过程
36 * @throws Exception
37 */
38 @Test
39 public void deSeria() throws Exception {
40 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("h:/kkk.data"));
41 Dog d = (Dog) ois.readObject();
42 ois.close();
43 //System.out.println("son link:" + d.getSon().getPerson().getName());//NullPointException
44 System.out.println("dog link:" + d.getPerson().getName());
45 }
46 }
47
48 class Person implements Serializable{
49
50 /**
51 *
52 */
53 private static final long serialVersionUID = -149817064278073579L;
54 private String name = "pName...";
55
56 public String getName() {
57 return name;
58 }
59
60 public void setName(String name) {
61 this.name = name;
62 }
63
64 }
65
66 class Son implements Serializable{
67 /**
68 *
69 */
70 private static final long serialVersionUID = -2553176111008776359L;
71 // transient:临时的，穿行化链中断
72 private transient Person person;
73 private String name = "dogkkk";
74
75 public Person getPerson() {
76 return person;
77 }
78 public void setPerson(Person person) {
79 this.person = person;
80 }
81 public String getName() {
82 return name;
83 }
84 public void setName(String name) {
85 this.name = name;
86 }
87
88 }
89
90 class Dog implements Serializable{
91 /**
92 *
93 */
94 private static final long serialVersionUID = -4168869841460181681L;
95 private Son son;
96 private String name;
97 private Person person;
98 public Son getSon() {
99 return son;
100 }
101 public void setSon(Son son) {
102 this.son = son;
103 }
104 public String getName() {
105 return name;
106 }
107 public void setName(String name) {
108 this.name = name;
109 }
110 public Person getPerson() {
111 return person;
112 }
113 public void setPerson(Person person) {
114 this.person = person;
115 }
116
117 }
反序列化对象时，是否经过构造函数，为什么
没有必要
成员变量中存储数据，成员函数只是行为，对象存在于堆区（对象的成员变量），串行化时抓取整个对象的状态，然后写到文件中去，反串行化时把属性值放在对应的位置，开辟空间放上对应值，不需要调用任何过程
ByteArrayInputStream&ByteArrayOutputStream
字节数组输入输出流，串行化到内存中
1 /**
2 * 使用ByteArrayInputStream + ByteArrayOutputStream实现对象图的复制
3 * @throws Exception
4 */
5 public static void deeplyCopyInBAOS() throws Exception {
6 Person p = new Person();
7 Son s = new Son();
8 Dog d = new Dog();
9 // 设置关联关系
10 s.setPerson(p);
11 d.setSon(s);
12 d.setPerson(p);
13 // 串行化
14 ByteArrayOutputStream baos = new ByteArrayOutputStream();
15 ObjectOutputStream oos = new ObjectOutputStream(baos);
16 oos.writeObject(d);
17 oos.close();
18 baos.close();
19
20 //
21 byte[] byteArray = baos.toByteArray();
22
23 // 反串行化
24 ByteArrayInputStream bais = new ByteArrayInputStream(byteArray);
25 ObjectInputStream ois = new ObjectInputStream(bais);
26 Dog d1 = (Dog) ois.readObject();
27 ois.close();
28 bais.close();
29 System.out.println("dog link:" + d1.getPerson().getName());
30 }
DataInputStream&DataOutputStream
1 import java.io.ByteArrayInputStream;
2 import java.io.ByteArrayOutputStream;
3 import java.io.DataInputStream;
4 import java.io.DataOutputStream;
5
6 import org.junit.Test;
7
8 public class DataIOStreamDemo {
9
10 /**
11 * DataArrayOutputStream
12 * @throws Exception
13 */
14 @Test
15 public void write() throws Exception{
16 ByteArrayOutputStream baos = new ByteArrayOutputStream();
17 DataOutputStream dos = new DataOutputStream(baos);
18 dos.writeByte(-1); //1
19 dos.writeShort(5); //2
20 dos.writeInt(10); //4
21 dos.writeLong(12L); //8
22 dos.writeFloat(0.5f); //4
23 dos.writeDouble(0.6); //8
24 dos.writeChar(‘a‘); //2
25 dos.writeBoolean(true); //1
26 dos.close();
27 baos.close();
28 byte[] bytes = baos.toByteArray();
29 System.out.println(bytes.length);
30
31 //反序列化
32 ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
33 DataInputStream dis = new DataInputStream(bais);
34 System.out.println(dis.readByte());
35 System.out.println(dis.readShort());
36 dis.close();
37 bais.close();
38 }
39 }
- Reader
- writer
- BufferedReader
- BufferedWriter
- LineNumberReader
- InputStream
- FileInputStream
- ByteArrayInputStream
- ObjectInputStream
- DataInputStream
- FilterInputStream
- OutputStreamWriter
时间： 2024-12-22 15:48:40