一、InputStreamReader和OutputStreamWriter

本专栏文章超详细的逐句介绍Java高级接口之文件输入/输出流函数FileReader和FileWriter函数源码讲解（全）的具体方法实现主要在文件输入/输出转换流函数InputStreamReader和OutputStreamWriter函数，下面我将从源码角度进行介绍。

二、OutputStreamWriter源码介绍

InputStreamReader继承于Writer

public class OutputStreamWriter extends Writer {
]

下面定义了流的编码规则

private final StreamEncoder se;

创建一个使用命名字符集的 OutputStreamWriter。

public OutputStreamWriter(OutputStream out, String charsetName)
        throws UnsupportedEncodingException
    {
        super(out);
        if (charsetName == null)
            throw new NullPointerException("charsetName");
        se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
    }

使用命名字符集创建输出转换流函数

public OutputStreamWriter(OutputStream out, String charsetName)
        throws UnsupportedEncodingException
    {
        super(out);
        if (charsetName == null)
            throw new NullPointerException("charsetName");
        se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
    }

创建一个使用默认字符编码的 OutputStreamWriter。

public OutputStreamWriter(OutputStream out) {
        super(out);
        try {
            se = StreamEncoder.forOutputStreamWriter(out, this, (String)null);
        } catch (UnsupportedEncodingException e) {
            throw new Error(e);
        }
    }

创建一个使用给定字符集的 OutputStreamWriter。

public OutputStreamWriter(OutputStream out, Charset cs) {
        super(out);
        if (cs == null)
            throw new NullPointerException("charset");
        se = StreamEncoder.forOutputStreamWriter(out, this, cs);
    }

按照指定的字符集合创建输出流函数

public OutputStreamWriter(OutputStream out, CharsetEncoder enc) {
        super(out);
        if (enc == null)
            throw new NullPointerException("charset encoder");
        se = StreamEncoder.forOutputStreamWriter(out, this, enc);
    }

获取编码规则

public String getEncoding() {
        return se.getEncoding();
    }

定义缓冲区

void flushBuffer() throws IOException {
        se.flushBuffer();
    }

定义写函数（写入整型）

public void write(int c) throws IOException {
        se.write(c);
    }

定义写函数（char数组）

public void write(char cbuf[], int off, int len) throws IOException {
        se.write(cbuf, off, len);
    }

定义写入字符串的方法

public void write(String str, int off, int len) throws IOException {
        se.write(str, off, len);
    }

定义刷新函数

public void flush() throws IOException {
        se.flush();
    }

定义关闭函数

 public void close() throws IOException {
        se.close();
    }

三、InputStreamReader函数介绍

InputStreamReader函数继承于Reader 类

public class InputStreamReader extends Reader {
}

定义流解码器

private final StreamDecoder sd;

用默认字符集创建文件输入流函数

public InputStreamReader(InputStream in) {
        super(in);
        try {
            sd = StreamDecoder.forInputStreamReader(in, this, (String)null); // ## check lock object
        } catch (UnsupportedEncodingException e) {
            // The default encoding should always be available
            throw new Error(e);
        }
    }

用指定字符集创建文件输入流函数

public InputStreamReader(InputStream in, String charsetName)
        throws UnsupportedEncodingException
    {
        super(in);
        if (charsetName == null)
            throw new NullPointerException("charsetName");
        sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
    }

创建一个使用给定字符集的 InputStreamReader。

public InputStreamReader(InputStream in, Charset cs) {
        super(in);
        if (cs == null)
            throw new NullPointerException("charset");
        sd = StreamDecoder.forInputStreamReader(in, this, cs);
    }

用指定的解码器创建一个新的 InputStreamReader

    public InputStreamReader(InputStream in, CharsetDecoder dec) {
        super(in);
        if (dec == null)
            throw new NullPointerException("charset decoder");
        sd = StreamDecoder.forInputStreamReader(in, this, dec);
    }

获取编码规则

public String getEncoding() {
        return sd.getEncoding();
    }

读取一个字符数

public int read() throws IOException {
        return sd.read();
    }

读取一个char数组

public int read(char cbuf[], int offset, int length) throws IOException {
        return sd.read(cbuf, offset, length);
    }

判断是否准备好了

public boolean ready() throws IOException {
        return sd.ready();
    }

定义流关闭函数

 public void close() throws IOException {
        sd.close();
    }