Java IO体系之OutputStreamWriter

迈不过友情╰ 2022-03-02 06:30 246阅读 0赞

## 介绍 ##

*  字符输出流Writer 的实现类

## 继承关系图 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3RoZWJpZ2RpcHBlcmJkeA_size_16_color_FFFFFF_t_70]

## 样例 ##

public static void main(String[] args) throws IOException{ 
        //创建字节输出流，绑定数据文件（没有则创建）
        FileOutputStream fos=new FileOutputStream("D:\\HELLO.txt");
        // 创建转换流对象，构造方法，绑定字节输出流
        OutputStreamWriter osw=new OutputStreamWriter(fos, "UTF-8");
        //转换流写数据（覆盖写）
        osw.append("春天到了").append("\r\n").append("春暖花开");
        osw.close();
        fos.close();
    }

## 源码 ##

package java.io;
    
    import java.nio.charset.Charset;
    import java.nio.charset.CharsetEncoder;
    import sun.nio.cs.StreamEncoder;
    
    public class OutputStreamWriter extends Writer { 
    
        private final StreamEncoder se;
    
        /** * Creates an OutputStreamWriter that uses the named charset. */
        public OutputStreamWriter(OutputStream out, String charsetName)
            throws UnsupportedEncodingException
        { 
            super(out);
            if (charsetName == null)
                throw new NullPointerException("charsetName");
            se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
        }
    
        /** * Creates an OutputStreamWriter that uses the default character encoding. * * @param out An OutputStream */
        public OutputStreamWriter(OutputStream out) { 
            super(out);
            try { 
                se = StreamEncoder.forOutputStreamWriter(out, this, (String)null);
            } catch (UnsupportedEncodingException e) { 
                throw new Error(e);
            }
        }
    
        /** * Creates an OutputStreamWriter that uses the given charset. * * @since 1.4 * @spec JSR-51 */
        public OutputStreamWriter(OutputStream out, Charset cs) { 
            super(out);
            if (cs == null)
                throw new NullPointerException("charset");
            se = StreamEncoder.forOutputStreamWriter(out, this, cs);
        }
    
        /** * Creates an OutputStreamWriter that uses the given charset encoder. * * @since 1.4 * @spec JSR-51 */
        public OutputStreamWriter(OutputStream out, CharsetEncoder enc) { 
            super(out);
            if (enc == null)
                throw new NullPointerException("charset encoder");
            se = StreamEncoder.forOutputStreamWriter(out, this, enc);
        }
    
        /** * Returns the name of the character encoding being used by this stream. * * <p> If the encoding has an historical name then that name is returned; * otherwise the encoding's canonical name is returned. * * * @revised 1.4 * @spec JSR-51 */
        public String getEncoding() { 
            return se.getEncoding();
        }
    
        /** * Flushes the output buffer to the underlying byte stream, without flushing * the byte stream itself. This method is non-private only so that it may * be invoked by PrintStream. */
        void flushBuffer() throws IOException { 
            se.flushBuffer();
        }
    
        /** * Writes a single character. * * @exception IOException If an I/O error occurs */
        public void write(int c) throws IOException { 
            se.write(c);
        }
    
        /** * Writes a portion of an array of characters. * * @param cbuf Buffer of characters * @param off Offset from which to start writing characters * @param len Number of characters to write * * @exception IOException If an I/O error occurs */
        public void write(char cbuf[], int off, int len) throws IOException { 
            se.write(cbuf, off, len);
        }
    
        /** * Writes a portion of a string. * * @param str A String * @param off Offset from which to start writing characters * @param len Number of characters to write * * @exception IOException If an I/O error occurs */
        public void write(String str, int off, int len) throws IOException { 
            se.write(str, off, len);
        }
    
        /** * Flushes the stream. * * @exception IOException If an I/O error occurs */
        public void flush() throws IOException { 
            se.flush();
        }
    
        public void close() throws IOException { 
            se.close();
        }
    }

## FileWriter源码 ##

package java.io;
    
    public class FileWriter extends OutputStreamWriter { 
    
        /** * Constructs a FileWriter object given a file name. * * @param fileName String The system-dependent filename. * @throws IOException if the named file exists but is a directory rather * than a regular file, does not exist but cannot be * created, or cannot be opened for any other reason */
        public FileWriter(String fileName) throws IOException { 
            super(new FileOutputStream(fileName));
        }
    
        /** * Constructs a FileWriter object given a file name with a boolean * indicating whether or not to append the data written. * * @param fileName String The system-dependent filename. * @param append boolean if <code>true</code>, then data will be written * to the end of the file rather than the beginning. * @throws IOException if the named file exists but is a directory rather * than a regular file, does not exist but cannot be * created, or cannot be opened for any other reason */
        public FileWriter(String fileName, boolean append) throws IOException { 
            super(new FileOutputStream(fileName, append));
        }
    
        /** * Constructs a FileWriter object given a File object. * * @param file a File object to write to. * @throws IOException if the file exists but is a directory rather than * a regular file, does not exist but cannot be created, * or cannot be opened for any other reason */
        public FileWriter(File file) throws IOException { 
            super(new FileOutputStream(file));
        }
    
        /** * Constructs a FileWriter object given a File object. If the second * argument is <code>true</code>, then bytes will be written to the end * of the file rather than the beginning. * * @param file a File object to write to * @param append if <code>true</code>, then bytes will be written * to the end of the file rather than the beginning * @throws IOException if the file exists but is a directory rather than * a regular file, does not exist but cannot be created, * or cannot be opened for any other reason * @since 1.4 */
        public FileWriter(File file, boolean append) throws IOException { 
            super(new FileOutputStream(file, append));
        }
    
        /** * Constructs a FileWriter object associated with a file descriptor. * * @param fd FileDescriptor object to write to. */
        public FileWriter(FileDescriptor fd) { 
            super(new FileOutputStream(fd));
        }
    
    }

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