Java多线程中的Balking模式详解

public class Data{
    private final String filename;//保存文件的名称
    private String content;//数据的内容
    private boolean changed;//内容是否已保存的标志，若修改后为保存，则为true

    public Data(String filename,String content){
        this.filename=filename;
        this.content=content;
        this.changed=true;
    }
    //修改数据内容
    public synchronized void change(String newContent){
        content=newContent;
        changed=true;
    }

    //若数据内容修改过,则保存到文件中
    public synchronized void save() throws IOException{
        if(!changed){
            return;
        }
        doSave();
        changed=false;
    }
    //将数据保存到文件中
    private void doSave() throws IOException {
        // TODO Auto-generated method stub
        StdOut.println(Thread.currentThread().getName()+" calls doSave,content= "+content);
        Writer writer=new FileWriter(filename);
        writer.write(content);
        writer.close();
    }
}

public class WriterThread extends Thread {
    private final Data data;
    private final Random random=new Random();
    public WriterThread(String name,Data data){
        super(name);
        this.data=data;
    }
    public void run(){
        try {
            for(int i=0;true;i++){
                data.change("NO."+i);//修改数据
                Thread.sleep(random.nextInt(1000));//执行其他操作
                data.save();
            }
        } catch (InterruptedException | IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

public class SaverThread extends Thread {
    private final Data data;
    public SaverThread(String name,Data data){
        super(name);
        this.data=data;
    }

    public void run(){
        try {
            while(true){
                data.save();//保存数据
                Thread.sleep(1000);//休眠约1秒
            }
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}

public class Main {

    public static void main(String[] args) {
        Data data=new Data("data1.txt", "empty");
        new WriterThread("ChangerThead",data).start();
        new SaverThread("SaverThread", data).start();
    }
}