本人测试的一个压缩文件， 为3.31G
下面提供了三种方法分别对文件进行分段操作，功能不同，坑也不同。
第一种读取的方法代码比较少，但是确实最好的一种方法.
因为我们用的byte数组， 数组是有长度的，而且长度是整数，整数是有界限的，所以在读取和操作的时候就会造成越界的情况。
第一种方法：在读取的时候采用分次读入和分次读取，这样的话，只要合理的划分分段写入得大小就不会有问题
第二种方法：在读取的时候， 因为是直接读取，所以文件不能太大（大概2G），太大就读取不了
第三种方法：其实跟第二种一样，只不过只是写入byte[];这种的方法在程序中也有可能会用到，所以也就研究了一下。比如网络传输，一个大文件会分几次发送，但是每次发送接受到的都是字节，这时候就需要用到这个方法了
1 using System.Collections;
2 using System.Collections.Generic;
3 using UnityEngine;
4 using System.IO;
5
6 public class IOTest : MonoBehaviour
7 {
8 public static int segWriteSize
9 {
10 get
11 {
12 return 1024 * 1024 * 5; //每次五兆
13 }
14 }
15
16 private void Start()
17 {
18 string path = @"E:1.zip";
19 string outpath = @"E:all.zip";
20 StartCoroutine(SegWrite(path, outpath));
21
22 //byte[] bs = File.ReadAllBytes(path);
23 //Debug.Log(bs.Length);
24 //StartCoroutine(SegWrite(bs, outpath));
25
26
27 //StartCoroutine(SegRead(path, outpath));
28 }
29
30 public static IEnumerator SegRead(string filepath, string outpath) //第一种
31 {
32 FileStream fswrite = File.OpenWrite(outpath);
33 FileStream fsread = new FileStream(filepath, FileMode.Open, FileAccess.Read);
34 BinaryReader r = new BinaryReader(fsread);
35 byte[] bs = r.ReadBytes(segWriteSize);
36 while(bs.Length != 0)
37 {
38 fswrite.Write(bs, 0, bs.Length);
39 fswrite.Flush();
40 yield return null;
41 Debug.Log("write.......");
42 bs = r.ReadBytes(segWriteSize);
43 }
44 fswrite.Close();
45
46 }
47
48 public static IEnumerator SegWrite(string filepath, string outpath) //分段写入 第2种
49 {
50 FileStream fsRead = File.OpenRead(filepath); //打开
51 byte[] buffer = new byte[segWriteSize]; //一次分段写入的大小
52 int segsize = buffer.Length; //分段的长度
53 int copied = 0; //标记长度
54 int filesize = 0; //一次写入的文件大小
55
56 FileStream fswrite = File.OpenWrite(outpath);
57 if (segsize < (int)fsRead.Length) //如果文件比分段写入的大，说明需要分段
58 {
59 while (copied + segsize <= (int)fsRead.Length) //分段写入
60 {
61 yield return null;
62 filesize = fsRead.Read(buffer, 0, buffer.Length); //一次读入的大小
63 fsRead.Flush();
64 fswrite.Write(buffer, 0, buffer.Length); //分次写入
65 fswrite.Flush();
66 copied += filesize;
67 Debug.Log("write........");
68 } //剩下的在写入
69 int left = (int)fsRead.Length - copied;
70 fsRead.Read(buffer, 0, left);
71 fsRead.Flush();
72 fswrite.Write(buffer, 0, left);
73 fswrite.Flush();
74 Debug.Log("write........");
75 }
76 else
77 {
78 buffer = new byte[(int)fsRead.Length];
79 fsRead.Read(buffer, 0, buffer.Length);
80 fsRead.Flush();
81 fswrite.Write(buffer, 0, buffer.Length);
82 fswrite.Flush();
83 }
84 fsRead.Close();
85 fsRead.Dispose();
86 fswrite.Close();
87 fswrite.Dispose();
88 Debug.Log("write finish");
89 }
90
91 public static IEnumerator SegWrite(byte[] bs, string outpath) //第三种
92 {
93 byte[] buffer = new byte[segWriteSize]; //一次分段写入的大小
94 int segsize = buffer.Length; //分段的长度
95 int copied = 0; //标记长度
96
97 FileStream fswrite = File.OpenWrite(outpath);
98 if (segsize < bs.Length) //如果文件比分段写入的大，说明需要分段
99 {
100 while (copied + segsize <= bs.Length)
101 {
102 buffer = new byte[segWriteSize];
103 for (int i = 0; i < segWriteSize; i++)
104 {
105 int index = copied + i;
106 buffer[i] = bs[index];
107 }
108 copied += segWriteSize;
109 fswrite.Write(buffer, 0, buffer.Length); //分次写入
110 fswrite.Flush();
111 yield return null;
112 Debug.Log("write........");
113 }
114 int left = bs.Length - copied;
115 buffer = new byte[left];
116 for (int i = 0; i < left; i++)
117 {
118 int index = copied + i;
119 buffer[i] = bs[index];
120 }
121 copied += left;
122 Debug.Log(copied);
123 fswrite.Write(buffer, 0, left);
124 fswrite.Flush();
125 yield return null;
126 Debug.Log("write........");
127 }
128 else
129 {
130 fswrite.Write(bs, 0, bs.Length);
131 fswrite.Flush();
132 }
133
134 fswrite.Close();
135 fswrite.Dispose();
136 Debug.Log("write finish");
137 }
138
139
140 }