How to merge input streams using SequenceInputStream function in Java

In Java development, we often need to merge multiple input streams to process data. The SequenceInputStream function is one of the functions provided in Java for merging input streams. It can merge multiple input streams into a larger input stream to facilitate our data processing.

So, how to use the SequenceInputStream function in Java to merge input streams? Next, this article will introduce its specific implementation methods and precautions through detailed steps.

1. Import the necessary packages

First, import the necessary packages at the beginning of the code:

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.SequenceInputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

Among them, SequenceInputStream is the class to be introduced in this article, and at the same time You also need to use the List collection class in Java.

2. Create input streams

Before we start merging input streams, we need to create multiple input streams. Here are two input streams as an example:

byte[] bytes1 = "hello".getBytes();
byte[] bytes2 = "world".getBytes();
InputStream inputStream1 = new ByteArrayInputStream(bytes1);
InputStream inputStream2 = new ByteArrayInputStream(bytes2);

First, we convert the strings "hello" and "world" into byte arrays respectively, and then convert the byte arrays into input streams through the ByteArrayInputStream class.

3. Merge input streams

Next, use the singletonList method of Collections to add the two input streams to a List collection:

List<InputStream> inputStreamList = Collections.singletonList(inputStream1);
inputStreamList.add(inputStream2);

Due to singletonList The List created by the method cannot be modified, so we need to use the add method to add a new input stream to it. In this way, half of the input stream merging work is completed.

4. Create a SequenceInputStream object

Finally, we only need to create a SequenceInputStream object and use the Collections.enumeration method to take out the input streams in the List collection one by one and pass them into the SequenceInputStream In the construction method:

InputStream inputStream = new SequenceInputStream(Collections.enumeration(inputStreamList));

In this way, we successfully merged the two input streams into a larger input stream.

The complete code is as follows:

import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.SequenceInputStream;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class SequenceInputStreamDemo {

    public static void main(String[] args) {

        byte[] bytes1 = "hello".getBytes();
        byte[] bytes2 = "world".getBytes();
        InputStream inputStream1 = new ByteArrayInputStream(bytes1);
        InputStream inputStream2 = new ByteArrayInputStream(bytes2);

        List<InputStream> inputStreamList = Collections.singletonList(inputStream1);
        inputStreamList.add(inputStream2);

        InputStream inputStream = new SequenceInputStream(Collections.enumeration(inputStreamList));

        byte[] resultBytes = new byte[10];
        try {
            inputStream.read(resultBytes);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(new String(resultBytes));
    }
}

It should be noted that the order of the input streams merged by SequenceInputStream is related to the order added in the List collection, because it takes out the input streams one by one and reads their contents continuously. Taken.

Summary:

By using the SequenceInputStream function in Java, we can easily merge multiple input streams into a larger input stream, making data processing simple and efficient. During the implementation process, we need to pay attention to the order of the input stream and the adding method of the List collection to ensure the correctness of the output results.

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