Bufferedinputstream buffer fill problem

BufferedInputStream The function of is to provide buffer function for other input streams . establish BufferedInputStream when , We will specify an input stream as a parameter through its constructor .BufferedInputStream The input stream data will be read in batches , Read a portion at a time into the buffer ; After this part of the buffer has been manipulated , And then read the next part of the data from the input stream .

problem

Recently, I encountered a problem in the process of communicating with the server , The size of the data stream returned by the server is 2602 Bytes , When I receive it on the client , These bytes cannot be read at one time . The sample code is as follows ：

byte[] buffer = new byte[2602];
//  Write the data in the buffer to the byte array buffer in .0 It's an array of bytes buffer Starting position ,2602 Is the write length 
int pos = read(buffer, 0, 2602);

The above example code is normal pos The value should be 2602, But sometimes it's 1434, Read 1434 Bytes .

analysis

First, let's be clear BufferedInputStream The default filling area is 8192 Bytes , This buffer is not filled at one time , It is filled in step by step , That is, after the user reads the current data , Refilled , So the cycle ends .

Solution

As described above 2602 byte , Is the data returned by the server , In the actual project, there must be variables , It depends on the length of the data returned by the server .

while Cyclic segmented reading

int num = 0;
while (num < 2602) {
    
    int pos = read(buffer, num, 2602 - num);  
    num += pos;
}

for Cycle a byte by byte reading

int num = 0;
for (int i=0;i<2602;i++) {
    
    buffer[i] = (byte)read();
    num++;
}