Java中的字符流与字节流

流是数据序列。 I/O 流 指不太可能是顺序访问文件的方法的流。 I/O 流是指代表不同类型源（例如磁盘文件）的输入源或输出目的地。 Java.io 包提供的类允许您在 Unicode字符流和非 Unicode 文本的字节流之间进行转换。

• 输入流：从源中读取数据。
• 输出流：将数据写入目的地。

When to use Character Stream over Byte Stream?

In Java, characters are stored using Unicode conventions. Character stream is useful when we want to process text files. These text files can be processed character by character. Character size is typically 16 bits.

When to use Byte Stream over Character Stream?  

Byte oriented reads byte by byte.  A byte stream is suitable for processing raw data like binary files.

使用和处理上述任何流时的要点如下：

1. 字符流的名称通常以 Reader/Writer 结尾，字节流的名称通常以 InputStream/OutputStream 结尾
2. 示例代码中使用的流是无缓冲的流，效率较低。我们通常将它们与缓冲读取器/写入器一起使用以提高效率。我们将很快讨论使用 BufferedReader/BufferedWriter（用于字符流）和 BufferedInputStream/BufferedOutputStream（用于字节流）类。
3. 如果不再使用，始终建议关闭流。这样可以确保发生任何错误时不会影响流。
4. 由于文件可能不存在，上述代码可能无法在在线编译器中运行。

字符流

在Java中，字符是使用 Unicode 约定存储的。字符流自动允许我们逐个字符字符读取/写入数据。例如，FileReader 和 FileWriter 是用于从源读取和写入目标的字符流。

例子

Java

// Java Program illustrate Reading
// a File in Human Readable
// Format Using FileReader Class
 
// Importing required classes
import java.io.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
        throws IOException
    {
 
        // Initially assiging null as we have not read
        // anything
        FileReader sourceStream = null;
 
        // Try block to check for exceptions
        try {
 
            // Reading from file
            sourceStream = new FileReader(
                "/Users/mayanksolanki/Desktop/demo.rtf");
 
            // Reading sourcefile and writing content to
            // target file character by character.
 
            int temp;
 
            // If there is content inside file
            // than read
            while ((temp = sourceStream.read()) != -1)
                System.out.println((char)temp);
           
          // Display message for successfu execution of program
          System.out.print("Program successfully executed");
        }
 
        // finally block that executes for sure
        // where we are closing file connections
        // to avoid memory leakage
        finally {
 
            // Closing stream as no longer in use
            if (sourceStream != null)
                sourceStream.close();
        }
    }
}

输出：字符字符目标文件

Program successfully executed

字节流

字节流逐字节（8 位）处理数据。例如，FileInputStream 用于从源读取，FileOutputStream 用于写入目标。

例子：

Java

// Java Program Illustrate ByteStream Class to
// Copy Contents of One File to Another File
 
// Importing required classes
import java.io.*;
 
// Main class
public class GFG {
 
    // Main driver method
    public static void main(String[] args)
        throws IOException
    {
 
        // Initially assigning null ot objects for
        // reading and writing to file
        FileInputStream sourceStream = null;
        FileOutputStream targetStream = null;
 
        // Try block to check for exceptions
        try {
 
            // Passing the files via lcoal directory
            sourceStream = new FileInputStream(
                "/Users/mayanksolanki/Desktop/demo.rtf");
            targetStream = new FileOutputStream(
                "/Users/mayanksolanki/Desktop/democopy.rtf");
 
            // Reading source file and writing content to
            // target file byte by byte
            int temp;
 
            // If there is content inside file
            // than read
            while ((temp = sourceStream.read()) != -1)
                targetStream.write((byte)temp);
           
          // Display message for successfu execution of program
          System.out.print("Program successfully executed");
        }
 
        // finally block that executes for sure
        // where we are closing file connections
        // to avoid memory leakage
        finally {
 
            if (sourceStream != null)
                sourceStream.close();
 
            if (targetStream != null)
                targetStream.close();
        }
    }
}

输出：

Program successfully executed