// 直接傳入Path默認是只讀FileChannel
FileChannel fileChannel = FileChannel.open(Path.of("./tmp/linshifu.txt"));
// 和直接傳入Path相比，支持傳入OpenOption數(shù)組
FileChannel channel = FileChannel.open(Path.of("./tmp/linshifu.txt"), StandardOpenOption.WRITE);

public enum StandardOpenOption implements OpenOption {
    // 可讀Channel
    READ,
    // 可寫Channel
    WRITE,
    // 如果Channel是可寫(WRITE)的，緩沖中的數(shù)據(jù)會從文件末尾開始寫，而不是從頭開始寫
    APPEND,
    // 如果Channel是可寫(WRITE)的，文件的長度會被置為0
    TRUNCATE_EXISTING,
    // 如果文件不存在，則會創(chuàng)建一個新的文件，如果配置了CREATE，則CREATE_NEW會失效
    CREATE,
    // 創(chuàng)建換一個新的文件，如果文件已經存在，則會失敗
    CREATE_NEW,
    // Channel關閉時刪除
    DELETE_ON_CLOSE,
    // 稀疏文件
    SPARSE,
    // 要求對文件內容或元數(shù)據(jù)的每次更新都同步寫入基礎存儲設備。
    SYNC,
    // 要求對文件內容的每次更新都同步寫入基礎存儲設備。
    DSYNC;
}

FileInputStream fileInputStream = new FileInputStream("./tmp/linshifu.txt");
FileChannel fileChannel = fileInputStream.getChannel();

FileOutputStream fileInputStream = new FileOutputStream("./tmp/linshifu.txt");
FileChannel fileChannel = fileInputStream.getChannel();

RandomAccessFile file = new RandomAccessFile("./tmp/linshifu.txt", "rw");
FileChannel fileChannel = file.getChannel();

// 從position位置讀取ByteBuffer.capacity個byte，Channel的position向后移動capacity個位置
public abstract int read(ByteBuffer dst) throws IOException;
// 從傳入的position開始讀取ByteBuffer.capacity個byte，Channel的positon位置不變
public abstract int read(ByteBuffer dst, long position) throws IOException;
// 按順序讀取文件到ByteBuffer數(shù)組中，會將數(shù)據(jù)讀取到ByteBuffer數(shù)組的[offset,offset+length)的ByteBuf子數(shù)組中
public abstract long read(ByteBuffer[] dsts, int offset, int length) throws IOException;

// 從position開始寫入ByteBuffer中的數(shù)據(jù)
public abstract int write(ByteBuffer src) throws IOException;
// 從position開始將ByteBuffer數(shù)組的[offset,offset+length)的ByteBuf子數(shù)組中的數(shù)據(jù)寫入文件
public abstract long write(ByteBuffer[] srcs, int offset, int length) throws IOException;
// 從position開始將ByteBuffer數(shù)組中的數(shù)據(jù)寫入文件
public final long write(ByteBuffer[] srcs) throws IOException {
    return write(srcs, 0, srcs.length);
}

public abstract void force(boolean metaData) throws IOException;

// 將字節(jié)從此通道的文件傳輸?shù)浇o定的可寫字節(jié)通道
public abstract long transferTo(long position, long count,WritableByteChannel target) throws IOException;
// 將字節(jié)從給定的可讀字節(jié)通道傳輸?shù)酱送ǖ赖奈募?
public abstract long transferFrom(ReadableByteChannel src,long position, long count) throws IOException;

public static void main(String[] args) throws Exception {
    RandomAccessFile file = new RandomAccessFile("./tmp/01.txt", "rw");
    MappedByteBuffer mbf = file.getChannel().map(FileChannel.MapMode.READ_WRITE, 0, 1024);
    mbf.put(0, (byte) 'a');
    file.close();
}