JavaIO流及多线程的学习[实验室第四讲]

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1.字节流
面向设备写入，无缓冲区。

    /**     * 字节流读取文件     * @throws IOException      */private static void readTest() throws IOException {    File file = new File("D:/java/file.txt");    FileReader fr = new FileReader(file);    System.out.println((char)fr.read());        //返回的是ASC码值    }    /**     * 字节流读取文件     * @throws IOException      */private static void readTest() throws IOException {    File file = new File("D:/java/file.txt");    FileReader fr = new FileReader(file);    char[] ch = new char[(int)file.length()];    fr.read(ch);    for(char c : ch){        System.out.println(c);    }            }

2.字符流
面向缓冲区操作。用flush()方法

    public static void writeTest() throws IOException{        //创建文件        File file = new File("D:/java/file.txt");        //用字符流向文件写入内容        FileWriter fw = new FileWriter(file);        fw.write("Android");        fw.flush();        fw.close();    }

缓冲流：

    /**     * 缓冲字符流读取操作     * @throws IOException      */    public static void bufferTest() throws IOException{        File file = new File("D:/java/file.txt");        FileReader fr = new FileReader(file);        BufferedReader br = new BufferedReader(fr);        System.out.println(br.readLine());    }

转换流
直接将你创建的流转换为writer的流，写入字符或者字符串

    /**     * 转换流     * @throws IOException      */    public static void OutputStreamWriter() throws IOException{        File file = new File("D:/java/file.txt");        FileOutputStream fos = new FileOutputStream(file);        OutputStreamWriter osw = new OutputStreamWriter(fos);        osw.write("Android",0,7);//字符，偏移量，写入的长度。        osw.flush();        osw.close();        }

对象流
将对象以文件的形式写入磁盘里保存起来。

    public static void ObjectText() throws IOException, ClassNotFoundException{        Person p = new Person("宁静",250);        File file = new File("D:/java/file.txt");/*        FileOutputStream fos = new FileOutputStream(file);        ObjectOutputStream oos = new ObjectOutputStream(fos);        oos.writeObject(p);        oos.flush();        oos.close();*/        FileInputStream fis = new FileInputStream(file);        ObjectInputStream ois = new ObjectInputStream(fis);        Person person = (Person) ois.readObject();        System.out.println(person);    }

多线程：
1.并发和并行
并行：在同一时刻，多件事情一定同时进行。
并发：在同一时刻，多件事情一定不是同时进行的。//轮流执行
3.创建线程开启线程
创建线程有两种基本方式：1).类

public class ThreadA extends Thread{    public ThreadA(String name){        super(name);    }    public void run(){        for(int i=0;i<10;i++)            System.out.println(getName() + "-->" + i);    }}public class ThreadB extends Thread{    public ThreadB(String name){        super(name);    }    public void run(){        for(int i=0;i<10;i++)            System.out.println(getName() + "-->" + i);    }}public class xiancheng {    public static void main(String[] args){        ThreadA tA = new ThreadA("线程A");        ThreadB tB = new ThreadB("线程B");        tA.start();        tB.start();    }}

2).Runnable接口

public class ThreadTask implements Runnable {    @Override    public void run() {        // TODO Auto-generated method stub        for(int i=0;i<10;i++)            System.out.println(Thread.currentThread().getName() + "-->" + i);        }}public class xiancheng {    public static void main(String[] args){        ThreadTask task = new ThreadTask();        Thread t = new Thread(task);        t.start();    }}

//两线程执行同一个任务public class ThreadTask implements Runnable {    private int num = 0;    private Object lock = new Object();//同步锁    @Override    public void run() {        // TODO Auto-generated method stub        while(num<100){            synchronized(lock)//同步代码块            {                num++;                System.out.println(Thread.currentThread().getName() + "-->" + num);            }        }    }}public class xiancheng {    public static void main(String[] args){        ThreadTask task = new ThreadTask();        Thread t1 = new Thread(task,"线程A");        Thread t2 = new Thread(task,"线程B");        t1.start();        t2.start();    }}

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