NIO全文

AsynchronousFileChannel

• 异步将数据写入文件

Futrue读取

Path path = Paths.get("/Users/mzx/Desktop/java/nio/test4.txt");
//创建
AsynchronousFileChannel afc = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
ByteBuffer bb = ByteBuffer.allocate(1024);
Future<Integer> future = afc.read(bb, 0);
while (!future.isDone()) {
    System.out.println("isDone");
}
bb.flip();
System.out.println(new String(bb.array(),0 ,bb.array().length));
afc.close();

CompletionHander读取

Path path = Paths.get("/Users/mzx/Desktop/java/nio/test4.txt");
//创建
AsynchronousFileChannel afc = AsynchronousFileChannel.open(path, StandardOpenOption.READ);
ByteBuffer bb = ByteBuffer.allocate(1024);
afc.read(bb, 0, bb, new CompletionHandler<Integer, ByteBuffer>() {
    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        //读取完成之后
        System.out.println(result);
        System.out.println(new String(attachment.array()));
    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        //失败
        exc.printStackTrace();
    }
});
System.out.println("finish");

Future写数据

Path path = Paths.get("/Users/mzx/Desktop/java/nio/test4.txt");
//创建
AsynchronousFileChannel afc = AsynchronousFileChannel.open(path, StandardOpenOption.WRITE);
ByteBuffer bb = ByteBuffer.allocate(1024);
bb.put("AsynchronousFileChannel".getBytes());
bb.flip();
Future<Integer> future = afc.write(bb, 0);
while (!future.isDone()) {
    System.out.println("isDone");
}
System.out.println("finish");
afc.close();

CompletionHander写数据

Path path = Paths.get("/Users/mzx/Desktop/java/nio/test4.txt");
//创建
AsynchronousFileChannel afc = AsynchronousFileChannel.open(path, StandardOpenOption.WRITE);
//ByteBuffer bb = ByteBuffer.wrap("AsynchronousFileChannel - CompletionHandler".getBytes());
ByteBuffer bb = ByteBuffer.allocate(1024);
bb.put("AsynchronousFileChannel - dawda".getBytes());
bb.flip();
afc.write(bb, 0, bb, new CompletionHandler<Integer, ByteBuffer>() {
    @Override
    public void completed(Integer result, ByteBuffer attachment) {
        System.out.println(result);
    }

    @Override
    public void failed(Throwable exc, ByteBuffer attachment) {
        exc.printStackTrace();
    }
});
System.out.println("finish");

Charset

• 字符集编码对象

//字符集对象
Charset charset = Charset.forName("UTF-8");
//编码器对象
CharsetEncoder ce = charset.newEncoder();
CharBuffer cb = CharBuffer.allocate(1024);
cb.put("你好helloworld");
cb.flip();
//编码
ByteBuffer bb = ce.encode(cb);
for (int i = 0; i < bb.limit(); i++) {
    System.out.println(bb.get());
}
//解码
bb.flip();
CharsetDecoder cd = charset.newDecoder();
CharBuffer dcb = cd.decode(bb);
//你好helloworld
System.out.println(dcb);

//gbk方式
Charset gbk = Charset.forName("GBK");
CharsetDecoder gbkcd = gbk.newDecoder();
bb.flip();
CharBuffer gbkcb = gbkcd.decode(bb);
//浣犲ソhelloworld
System.out.println(gbkcb);

• 获取支持的字符编码

SortedMap<String, Charset> map = Charset.availableCharsets();
for (Map.Entry<String, Charset> sce : map.entrySet()) {
    System.out.println(sce.getKey() + " - " + sce.getValue());
}

• 其他

//默认编码
System.out.println(Charset.defaultCharset());
//是否支持某个编码
System.out.println(Charset.isSupported("UTF-8"));