复制代码代码如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace UseStream
{
class Program
{
//示例如何从流中读取字节流
static void Main(string[] args)
{
var bytes = new byte[] {(byte)1,(byte)2,(byte)3,(byte)4,(byte)5,(byte)6,(byte)7,(byte)8};
using (var memStream = new MemoryStream(bytes))
{
int offset = 0;
int readOnce = 4;
do
{
byte[] byteTemp = new byte[readOnce];
// 使用Read方法从流中读取字节
//第一个参数byte[]存储从流中读出的内容
//第二个参数为存储到byte[]数组的开始索引，
//第三个int参数为一次最多读取的字节数
//返回值是此次读取到的字节数，此值小于等于第三个参数
int readCn = memStream.Read(byteTemp, 0, readOnce);
for (int i = 0; i < readCn; i++)
{
Console.WriteLine(byteTemp[i].ToString());
}

offset += readCn;

//当实际读取到的字节数小于设定的读取数时表示到流的末尾了
if (readCn < readOnce) break;
} while (true);
}
Console.Read();
}
}
}

复制代码代码如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;
namespace UseBeginRead
{
class Program
{
//定义异步读取状态类
class AsyncState
{
public FileStream FS { get; set; }

public byte[] Buffer { get; set; }

public ManualResetEvent EvtHandle { get; set; }
}
static int bufferSize = 512;
static void Main(string[] args)
{
string filePath = "d:\\test.txt";
//以只读方式打开文件流
using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))
{
var buffer = new byte[bufferSize];

//构造BeginRead需要传递的状态
var asyncState = new AsyncState { FS = fileStream, Buffer = buffer ,EvtHandle = new ManualResetEvent(false)};

//异步读取
IAsyncResult asyncResult = fileStream.BeginRead(buffer, 0, bufferSize, new AsyncCallback(AsyncReadCallback), asyncState);

//阻塞当前线程直到读取完毕发出信号
asyncState.EvtHandle.WaitOne();
Console.WriteLine();
Console.WriteLine("read complete");
Console.Read();
}
}
//异步读取回调处理方法
public static void AsyncReadCallback(IAsyncResult asyncResult)
{
var asyncState = (AsyncState)asyncResult.AsyncState;
int readCn = asyncState.FS.EndRead(asyncResult);
//判断是否读到内容
if (readCn > 0)
{
byte[] buffer;
if (readCn == bufferSize) buffer = asyncState.Buffer;
else
{
buffer = new byte[readCn];
Array.Copy(asyncState.Buffer, 0, buffer, 0, readCn);
}

//输出读取内容值
string readContent = Encoding.UTF8.GetString(buffer);
Console.Write(readContent);
}

if (readCn < bufferSize)
{
asyncState.EvtHandle.Set();
}
else {
Array.Clear(asyncState.Buffer, 0, bufferSize);
//再次执行异步读取操作
asyncState.FS.BeginRead(asyncState.Buffer, 0, bufferSize, new AsyncCallback(AsyncReadCallback), asyncState);
}
}
}
}

复制代码代码如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace UseStreamWrite
{
class Program
{
static void Main(string[] args)
{
using (var ms = new MemoryStream())
{
int count = 20;
var buffer = new byte[count];
for (int i = 0; i < count; i++)
{
buffer[i] = (byte)i;
}

//将流当前位置设置到流的起点
ms.Seek(0, SeekOrigin.Begin);

Console.WriteLine("ms position is " + ms.Position);

//注意在调用Stream的Write方法之前要用CanWrite判断Stream是否可写
if (ms.CanWrite)
{
ms.Write(buffer, 0, count);
}

//正确写入的话，流的位置会移动到写入开始位置加上写入的字节数
Console.WriteLine("ms position is " + ms.Position);
}

Console.Read();
}
}
}

复制代码代码如下:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Threading;
namespace UseStreamBeginWrite
{
class Program
{
/// <summary>
/// 异步回调需要的参数封装类
/// </summary>
class AsyncState {
public int WriteCountOnce { get; set; }
public int Offset { get; set; }
public byte[] Buffer { get; set; }
public ManualResetEvent WaitHandle { get; set; }
public FileStream FS { get; set; }
}
static void Main(string[] args)
{
//准备一个1K的字节数组
byte[] toWriteBytes = new byte[1 << 10];
for (int i = 0; i < toWriteBytes.Length; i++)
{
toWriteBytes[i] = (byte)(i % byte.MaxValue);
}
string filePath = "d:\\test.txt";
//FileStream实例
using (var fileStream = new FileStream(filePath, FileMode.Create, FileAccess.ReadWrite, FileShare.Read))
{
int offset = 0;
//每次写入32字节
int writeCountOnce = 1 << 5;
//构造回调函数需要的状态
AsyncState state = new AsyncState{
WriteCountOnce = writeCountOnce,
Offset = offset,
Buffer = toWriteBytes,
WaitHandle = new ManualResetEvent(false),
FS = fileStream
};

//做异步写操作
fileStream.BeginWrite(toWriteBytes, offset, writeCountOnce, WriteCallback, state);

//等待写完毕或者出错发出的继续信号
state.WaitHandle.WaitOne();
}
Console.WriteLine("Done");
Console.Read();
}
/// <summary>
/// 异步写的回调函数
/// </summary>
/// <param name="asyncResult">写状态</param>
static void WriteCallback(IAsyncResult asyncResult)
{
AsyncState state = (AsyncState)asyncResult.AsyncState;

try
{
state.FS.EndWrite(asyncResult);
}
catch (Exception ex)
{
Console.WriteLine("EndWrite Error:" + ex.Message);
state.WaitHandle.Set();
return;
}

Console.WriteLine("write to " + state.FS.Position);
//判断是否写完，未写完继续异步写
if (state.Offset + state.WriteCountOnce < state.Buffer.Length)
{
state.Offset += state.WriteCountOnce;
Console.WriteLine("call BeginWrite again");
state.FS.BeginWrite(state.Buffer, state.Offset, state.WriteCountOnce, WriteCallback, state);
}
else {
//写完发出完成信号
state.WaitHandle.Set();
}
}
}
}