Java InputStreamReader用法及代碼示例

InputStreamReader 是一座來自字節流到字符流。它讀取字節並使用指定的字符集將它們解碼為字符。它使用的字符集可以通過名稱指定或可以顯式給出，或者可以接受平台的默認字符集。
聲明：

public class InputStreamReader
   extends Reader

構造函數：

輸入流讀取器(輸入流in_strm)：創建使用默認字符集的InputStreamReader。
InputStreamReader(InputStream in_strm，字符集cs)：創建使用給定字符集的InputStreamReader。
InputStreamReader(InputStream in_strm, CharsetDecoder dec):創建使用給定字符集解碼器的InputStreamReader。
InputStreamReader(InputStream in_strm, 字符串字符集名稱):創建使用命名字符集的 InputStreamReader

方法：

ready(): java.io.InputStreamReader.ready()指示字符流是否已準備好讀取。如果 InputStreamReader 的輸入緩衝區不為空，或者可以從底層字節流中讀取字節，則 InputStreamReader 已準備就緒。
句法：

public boolean ready()
返回：
True : if the Character stream is ready to be read
False : if the Character stream is not ready to be read

close(): java.io.InputStreamReader.close()關閉InputStreamReader並釋放與其關聯的所有流。關閉流後，進一步的 read()、ready()、mark()、reset() 或 skip() 調用將拋出 IOException。
句法：

public void close()
返回：
No value is returned

ready()和close()方法的實現：

Java


// Java program illustrating ready() and close() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args)
    {
        try
        {
            // initializing FileInputStream
            FileInputStream geek = new FileInputStream("ABC.txt");
            // Initializing InputStreamReader object
            InputStreamReader in_strm = new InputStreamReader(geek);
            int t;
            while((t=in_strm.read())!= -1)
            {
                // convert the integer true to character
                char r = (char)t;
                System.out.println("Character : "+r);
                // check if the stream in_strm ready
                boolean b = in_strm.ready();
                // Use of ready() methods
                System.out.println("Ready? : "+b);
            }
             
            // Use of close() method to Close InputStreamReader
            in_strm.close();
             
            // Closing FileInputStream
            geek.close();
        }
        catch (FileNotFoundException fnfe)
        {
            System.out.println("NO Such File Exists");
        }
        catch (IOException except)
        {
            System.out.println("IOException occurred");
        }
    }
}

筆記：
本文中的所有程序都不會在在線 IDE 上運行，因為不存在“ABC”文件。您可以在係統上的 Java 編譯器上檢查此代碼。
要檢查此代碼，請在您的係統上創建一個文件“ABC”。
“ABC”文件包含：
極客
為了
極客
輸出：

Character : G
Ready? : true
Character : e
Ready? : true
Character : e
Ready? : true
Character : k
Ready? : true
Character : s
Ready? : true
Character :  
Ready? : true
Character : 
Ready? : true
Character : 

Ready? : true
Character : F
Ready? : true
Character : o
Ready? : true
Character : r
Ready? : true
Character :  
Ready? : true
Character : 
Ready? : true
Character : 

Ready? : true
Character : G
Ready? : true
Character : e
Ready? : true
Character : e
Ready? : true
Character : k
Ready? : true
Character : s
Ready? : false

getEncoding(): java.io.InputStreamReader.getEncoding()返回該流所使用的字符編碼的名稱。
句法：

public String getEncoding()
Parameters : 
返回：
No value is returned

getEncoding()方法的實現：

Java


// Java program illustrating getEncoding() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args)
    {
        try
        {
            // initializing FileInputStream
            FileInputStream geek = new FileInputStream("ABC.txt");
            // Initializing InputStreamReader object
            InputStreamReader in_strm = new InputStreamReader(geek);
            // Use of getEncoding() method
            // to get the character encoding present in the stream
            String encoding = in_strm.getEncoding();
            System.out.println("Encoding used : "+encoding);
            // Closing InputStreamReader
            in_strm.close();
             
            // Closing FileInputStream
            geek.close();
        }
        catch (FileNotFoundException fnfe)
        {
            System.out.println("NO Such File Exists");
        }
        catch (IOException except)
        {
            System.out.println("IOException occurred");
        }
    }
}

輸出：

Encoding used : UTF8

read(): java.io.InputStreamReader.read()讀取後返回單個字符。
句法：

public int read()
返回：
Returns single character after reading or -1 if the end of the stream has been reached

執行：

Java


// Java program illustrating read() method
import java.io.*;
public class NewClass
{
    public static void main(String[] args) throws FileNotFoundException, IOException
    {
        // initializing FileInputStream
        FileInputStream geek = new FileInputStream("ABC.txt");
        // Initializing InputStreamReader object
        InputStreamReader in_strm = new InputStreamReader(geek);
        int t;
        String read_reslt="";
        // Use of read() method
        while((t = in_strm.read()) != -1)
        {
            read_reslt = read_reslt+(char)t;
        }
     
        // print the result read from the file
        System.out.println(read_reslt);
    }
}

筆記：
“ABC”文件包含：
1
極客
2
為了
3
極客
輸出：

1
Geeks 
2
For 
3
Geeks

相關用法

注：本文由純淨天空篩選整理自佚名大神的英文原創作品 InputStreamReader class in Java。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。