Reader and Writer:
Reader按照自定义的编码从输入流中进行读取
Writer按照自定义的编码写入输出流
InputStreamReader:
在初始化的时候传入自定义的编码以及输入流,并生成解码器进行读操作。
public InputStreamReader(InputStream in, String charsetName)
throws UnsupportedEncodingException
{
super(in);
if (charsetName == null)
throw new NullPointerException("charsetName");
sd = StreamDecoder.forInputStreamReader(in, this, charsetName);
}
在read的时候调用解码器的read方法
public int read() throws IOException {
return sd.read();
}
观察一下可以发现InputStreamReader使用了适配器的设计模式,在InputStream的read方法外加了一层Reader的read方法的壳,同时增加了按照固定编码进行解码的功能。
OutputStreamWriter:
在初始化的时候传入自定义的编码以及输出流,并生成编码器进行写操作。
public OutputStreamWriter(OutputStream out, String charsetName)
throws UnsupportedEncodingException
{
super(out);
if (charsetName == null)
throw new NullPointerException("charsetName");
se = StreamEncoder.forOutputStreamWriter(out, this, charsetName);
}
在write的时候调用编码器的write方法
public void write(int c) throws IOException {
se.write(c);
}
Reader和Writer的不同:
Reader的read方法直接返回读取的值
public int read(char cbuf[]) throws IOException {
return read(cbuf, 0, cbuf.length);
}
Writer的write方法将数据写入Writer中的writerBuffer中,如果需要往输出流里写的话需要调用flash或者close方法
public void write(String str, int off, int len) throws IOException {
synchronized (lock) {
char cbuf[];
if (len <= WRITE_BUFFER_SIZE) {
if (writeBuffer == null) {
writeBuffer = new char[WRITE_BUFFER_SIZE];
}
cbuf = writeBuffer;
} else { // Don't permanently allocate very large buffers.
cbuf = new char[len];
}
str.getChars(off, (off + len), cbuf, 0);
write(cbuf, 0, len);
}
}
装饰类:
PrintWriter,BufferedWriter,BufferedReader