ByteArrayOutputStream和ByteArrayInputStream详解

http://blog.sina.com.cn/s/blog_4c341e2101009f1j.html

ByteArrayOutputStream类是在创建它的实例时，程序内部创建一个byte型别数组的缓冲区，然后利用ByteArrayOutputStream和ByteArrayInputStream的实例向数组中写入或读出byte型数据。在网络传输中我们往往要传输很多变量，我们可以利用ByteArrayOutputStream把所有的变量收集到一起，然后一次性把数据发送出去。具体用法如下:

ByteArrayOutputStream:    可以捕获内存缓冲区的数据，转换成字节数组。

ByteArrayInputStream: 可以将字节数组转化为输入流

import java.io.*;

public class test {
 public static void main(String[] args) {
  int a=0;
  int b=1;
  int c=2;
  ByteArrayOutputStream bout = new ByteArrayOutputStream();
  bout.write(a);
  bout.write(b);
  bout.write(c);
  byte[] buff = bout.toByteArray();
  for(int i=0; i<buff.length; i++)
   System.out.println(buff[i]);
  System.out.println("***********************");
  ByteArrayInputStream bin = new ByteArrayInputStream(buff);
  while((b=bin.read())!=-1) {
   System.out.println(b);
  }
 }
}

如上所示,ByteArrayOutputStream把内存中的数据读到字节数组中,而ByteArrayInputStream又把字节数组中的字节以流的形式读出,实现了对同一个字节数组的操作.

综合DataOutputStream&DataInputStream的作用和功能,与ByteArrayOutputStream和ByteArrayInputSream使用将更方便.此时DataOutputStream&DataInputStream封闭了字节流,以适当的形式读出了字节数组中的数据.如下所示:

import java.io.*;

public class test {
 public static void main(String[] args)throws IOException {
  ByteArrayOutputStream bout = new ByteArrayOutputStream();
  DataOutputStream dout = new DataOutputStream(bout);
  String name = "xxy";
  int age = 84;
  dout.writeUTF(name);
  dout.writeInt(age);
  byte[] buff = bout.toByteArray();
  ByteArrayInputStream bin = new ByteArrayInputStream(buff);
  DataInputStream dis = new DataInputStream(bin);
  String newName = dis.readUTF();
  int newAge = dis.readInt();
  System.out.println(newName+":"+newAge);
 }
}

 

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http://blog.sina.com.cn/s/blog_4fb27fd80100obuc.html

ByteArrayOutputStream 类使用实例

(2011-01-01 18:36:27)

转载▼

标签： bytearray outputstream it

分类： Java项目

import java.util.*;

02	import java.io.*;

03

04	public class Person implements Serializable, ObjectInputValidation {

05

06	static Map thePeople = new HashMap();

07

08	private String name;

09	private String ss;

10

11	public Person(String name, String ss) {

12	this.name = name;

13	this.ss = ss;

14	thePeople.put(ss, name);

15

}

16

17	private void readObject(ObjectInputStream in)

18	throws IOException, ClassNotFoundException {

19	in.registerValidation(this, 5);

20	in.defaultReadObject();

21

}

22

23	public void validateObject() throws InvalidObjectException {

24	if (thePeople.containsKey(this.ss)) {

25	throw new InvalidObjectException(this.name + " already exists");

26

}

27

else {

28	thePeople.put(this.ss, this.name);

29

}

30

}

31

32	public String toString() {

33	return this.name + "\t" + this.ss;

34

}

35

36	public static void main(String[] args)

37	throws IOException, ClassNotFoundException {

38

39	Person p1 = new Person("Rusty", "123-45-5678");

40	Person p2 = new Person("Beth",  "321-45-5678");

41	Person p3 = new Person("David", "453-45-5678");

42	Person p4 = new Person("David", "453-45-5678");

43

44	Iterator iterator = thePeople.values().iterator();

45	while (iterator.hasNext()) {

46	System.out.println(iterator.next());

47

}

48

49	ByteArrayOutputStream bout = new ByteArrayOutputStream();

50	ObjectOutputStream oout = new ObjectOutputStream(bout);

51	oout.writeObject(p1);

52	oout.writeObject(p2);

53	oout.writeObject(p3);

54	oout.writeObject(p4);

55	oout.flush();

56	oout.close();

57

58	ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());

59	ObjectInputStream oin = new ObjectInputStream(bin);

60

try {

61	System.out.println(oin.readObject());

62	System.out.println(oin.readObject());

63	System.out.println(oin.readObject());

64	System.out.println(oin.readObject());

65

}

66	catch (InvalidObjectException ex) {

67	System.err.println(ex);

68

}

69	oin.close();

70

71	// now empty the map and try again

72	thePeople.clear();

73	bin = new ByteArrayInputStream(bout.toByteArray());

74	oin = new ObjectInputStream(bin);

75

try {

76	System.out.println(oin.readObject());

77	System.out.println(oin.readObject());

78	System.out.println(oin.readObject());

79	System.out.println(oin.readObject());

80

}

81	catch (InvalidObjectException ex) {

82	System.err.println(ex);

83

}

84	oin.close();

85

86	iterator = thePeople.values().iterator();

87	while (iterator.hasNext()) {

88	System.out.println(iterator.next());

89

}

90

}

91

}

import java.util.*;

02	import java.io.*;

03

04	public class Person implements Serializable, ObjectInputValidation {

05

06	static Map thePeople = new HashMap();

07

08	private String name;

09	private String ss;

10

11	public Person(String name, String ss) {

12	this.name = name;

13	this.ss = ss;

14	thePeople.put(ss, name);

15

}

16

17	private void readObject(ObjectInputStream in)

18	throws IOException, ClassNotFoundException {

19	in.registerValidation(this, 5);

20	in.defaultReadObject();

21

}

22

23	public void validateObject() throws InvalidObjectException {

24	if (thePeople.containsKey(this.ss)) {

25	throw new InvalidObjectException(this.name + " already exists");

26

}

27

else {

28	thePeople.put(this.ss, this.name);

29

}

30

}

31

32	public String toString() {

33	return this.name + "\t" + this.ss;

34

}

35

36	public static void main(String[] args)

37	throws IOException, ClassNotFoundException {

38

39	Person p1 = new Person("Rusty", "123-45-5678");

40	Person p2 = new Person("Beth",  "321-45-5678");

41	Person p3 = new Person("David", "453-45-5678");

42	Person p4 = new Person("David", "453-45-5678");

43

44	Iterator iterator = thePeople.values().iterator();

45	while (iterator.hasNext()) {

46	System.out.println(iterator.next());

47

}

48

49	ByteArrayOutputStream bout = new ByteArrayOutputStream();

50	ObjectOutputStream oout = new ObjectOutputStream(bout);

51	oout.writeObject(p1);

52	oout.writeObject(p2);

53	oout.writeObject(p3);

54	oout.writeObject(p4);

55	oout.flush();

56	oout.close();

57

58	ByteArrayInputStream bin = new ByteArrayInputStream(bout.toByteArray());

59	ObjectInputStream oin = new ObjectInputStream(bin);

60

try {

61	System.out.println(oin.readObject());

62	System.out.println(oin.readObject());

63	System.out.println(oin.readObject());

64	System.out.println(oin.readObject());

65

}

66	catch (InvalidObjectException ex) {

67	System.err.println(ex);

68

}

69	oin.close();

70

71	// now empty the map and try again

72	thePeople.clear();

73	bin = new ByteArrayInputStream(bout.toByteArray());

74	oin = new ObjectInputStream(bin);

75

try {

76	System.out.println(oin.readObject());

77	System.out.println(oin.readObject());

78	System.out.println(oin.readObject());

79	System.out.println(oin.readObject());

80

}

81	catch (InvalidObjectException ex) {

82	System.err.println(ex);

83

}

84	oin.close();

85

86	iterator = thePeople.values().iterator();

87	while (iterator.hasNext()) {

88	System.out.println(iterator.next());

89

}

90

}

91

}