---
title:  Java IO
category: Java
tag:
  - Java IO
  - Java
---

 IO 

## 

**Decorator** 

IO 

 `FilterInputStream` `FilterOutputStream` `InputStream` `OutputStream`

`BufferedInputStream`()`DataInputStream` `FilterInputStream` `BufferedOutputStream``DataOutputStream``FilterOutputStream`

 `BufferedInputStream` `FileInputStream` 

`BufferedInputStream` 

```java
public BufferedInputStream(InputStream in) {
    this(in, DEFAULT_BUFFER_SIZE);
}

public BufferedInputStream(InputStream in, int size) {
    super(in);
    if (size ... events)
    throws IOException;
```

 3 

- `StandardWatchEventKinds.ENTRY_CREATE` 
- `StandardWatchEventKinds.ENTRY_DELETE` : 
- `StandardWatchEventKinds.ENTRY_MODIFY` : 

`register`  `WatchKey` `WatchKey` 

```java
WatchKey key;
while ((key = watchService.take()) != null) {
    for (WatchEvent event : key.pollEvents()) {
      //  WatchEvent 
    }
    key.reset();
}
```

`WatchService`  daemon thread

```java
class PollingWatchService
    extends AbstractWatchService
{
    //  daemon thread
    private final ScheduledExecutorService scheduledExecutor;

    PollingWatchService() {
        scheduledExecutor = Executors
            .newSingleThreadScheduledExecutor(new ThreadFactory() {
                 @Override
                 public Thread newThread(Runnable r) {
                     Thread t = new Thread(r);
                     t.setDaemon(true);
                     return t;
                 }});
    }

  void enable(Set> events, long period) {
    synchronized (this) {
      // 
      this.events = events;

        // 
      Runnable thunk = new Runnable() { public void run() { poll(); }};
      this.poller = scheduledExecutor
        .scheduleAtFixedRate(thunk, period, period, TimeUnit.SECONDS);
    }
  }
}
```

## 

- Patterns in Java APIshttp://cecs.wright.edu/~tkprasad/courses/ceg860/paper/node26.html
-  Java IO https://time.geekbang.org/column/article/204845
- sun.nio  java  - RednaxelaFX https://www.zhihu.com/question/29237781/answer/43653953