本文主要是介绍Lesson_for_java_day18--java中的IO流(序列化、ByteArrayStream、DataStream、RandowAccessFile)，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
一、序列化：
package sonyi;import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;public class SerializeDemo {public static void main(String[] args) {// TODO Auto-generated method stubwrite();//写read();//读}//反序列化public static void read(){ObjectInputStream ois = null;try {ois = new ObjectInputStream(new FileInputStream("obj.txt"));ArrayList<Person> arr = (ArrayList<Person>)ois.readObject();for(Person p:arr){//按顺序读取对象System.out.println(p);}} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(ois != null)ois.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}//序列化public static void write(){ObjectOutputStream oos = null;ArrayList<Person> arr = new ArrayList<Person>();//创建容器装对象try {oos = new ObjectOutputStream(new FileOutputStream("obj.txt"));arr.add(new Person("zhangsan", 25));arr.add(new Person("lisi", 26));arr.add(new Person("wangwu", 27));oos.writeObject(arr);//将容器作为对象传递给流 //System.out.println(oos);} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(oos != null)oos.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}class Person implements Serializable{private String name;private int age;Person(String name,int age){this.name = name;this.age = age;}@Overridepublic String toString() {return "Person [name=" + name + ", age=" + age + "]";}public String getName() {return name;}public void setName(String name) {this.name = name;}public int getAge() {return age;}public void setAge(int age) {this.age = age;}
}二、ByteArrayStream
package io;import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;/*用于操作字节数组的流对象：ByteArrayInputStream:在构造的时候，需要接收数据源，而且数据源是一个字节数组ByteArrayOutputStream:在构造的时候，不用定义数据目的，因为该对象中已经内部封装了可变长度的字节数组这就是数据目的地。因为这两个流对象都操作的数组，并没有使用系统资源，所以不用进行close关闭。在流操作的讲解时：源设备：键盘(System.in)、硬盘(FileStream)、内存(ArrayStream)目的设备：控制台(System.out)、硬盘(FileStream)、内存(ArrayStream)用流的读写思想来操作数组。*/
public class ByteArrayStream {public static void main(String[] args) {// TODO Auto-generated method stub//数据源ByteArrayInputStream bis = new ByteArrayInputStream("abdcefg".getBytes());//数据目的ByteArrayOutputStream bos = new ByteArrayOutputStream();int by = 0;while((by = bis.read()) != -1){bos.write(by);}System.out.println(bos.size());System.out.println(bos.toString());//bos.writeTo(new FileOutputStream("a.txt"));}
}
三、DataStream
package io;import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;/*基本数据类型流对象：DataInputStream与DataOutputStream:可以用于操作基本数据类型的数据的流对象*/
public class DataStreamDemo {public static void main(String[] args) {
// writeData();
// readData();writeUTFDemo();readUTFDemo();}public static void readUTFDemo(){DataInputStream dis = null;try {dis = new DataInputStream(new FileInputStream("utfdata.txt"));String s = dis.readUTF();System.out.println(s);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(dis != null)dis.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}public static void writeUTFDemo(){DataOutputStream dos = null;try {dos = new DataOutputStream(new FileOutputStream("utfdata.txt"));dos.writeUTF("你好");} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(dos != null)dos.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}public static void readData(){DataInputStream dis = null;try {dis = new DataInputStream(new FileInputStream("data.txt"));int num = dis.readInt();boolean b = dis.readBoolean();double d = dis.readDouble();System.out.println("num = " + num);System.out.println("b = " + b);System.out.println("d = " + d); } catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(dis != null)dis.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}public static void writeData(){DataOutputStream dos = null;try {dos = new DataOutputStream(new FileOutputStream("data.txt"));dos.writeInt(124);dos.writeBoolean(true);dos.writeDouble(9887.123);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try {if(dos != null)dos.close();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}
四、RandowAccessFile
package io;import java.io.RandomAccessFile;
/*RandowAccessFile：(可以实现多线程对文件的同时操作。比如下载)随机访问文件该类不算是IO体系中子类，而是直接继承自Object。但是它是IO包中成员，因为它具备读和写功能，内部封装了一个数组，而且通过指针对数组的元素进行操作，可以通过getFilePointer获取指针位置。同时可以通过seek改变指针的位置。其实完成读写的原理就是内部封装了字节输入流和输出流。通过构造函数可以看出，该类自能操作文件。而且操作文件还有模式:只读r，读写rw等。如果模式为只读，不会创建文件，会去读取一个已存在的文件，如果该文件不存在，则会出现异常如果模式为读写，那么该对象的构造函数要操作的文件如果不存在，会自动创建，如果存在，不会覆盖*/
public class RandowAccessFileDemo {public static void main(String[] args){try {//writeFile();//readFile();writeFile_2();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}public static void readFile() throws Exception{RandomAccessFile raf = new RandomAccessFile("ran.txt", "r");//调整对象中指针，可以随意设置//raf.seek(8);//访问第二个对象了//跳过指定的字节数raf.skipBytes(8);//只能往后调，不能往回调byte[] buf = new byte[4];raf.read(buf);String name = new String(buf);int age = raf.readInt();System.out.println("name = " + name + ",age = " + age);raf.close();}public static void writeFile_2() throws Exception{RandomAccessFile raf = new RandomAccessFile("ran.txt", "rw");//raf.seek(8*3);//跳到指定位置raf.write("周期".getBytes());raf.writeInt(103);raf.close();}public static void writeFile() throws Exception{RandomAccessFile raf = new RandomAccessFile("ran.txt", "rw");raf.write("李四".getBytes());raf.writeInt(97);raf.write("王五".getBytes());raf.writeInt(98);raf.close();}
}
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