以前感觉 io系统的接口、类等比较乱，这次因为要解 zip压缩文件，不得不研究了下，感觉略有收获，先记录下。
File类表示是什么？
//文件名、文件夹名的抽象表示[消除了系统相关性如 windows/linux表示文件名的方式是不同的有"\" "/"之分]
An abstract representation of file and directory pathnames.
public File(String pathname) {}
是User interfaces，文件的创建、删除等都用 File的成员函数 to文件路径名的转换关系是：
file.toString()或者file.getPath()； File file = new File("file name")
写文件 FileOutputStream
input/output和读写的关系有点乱，记住一句话：从输入流中读数据，写数据到输出流里。
OutputStream是有关输出流的抽象类，不止是文件、显示器等都可以用
FileOutputStream //是 字节的方式不是char
class FileOutputStream extends OutputStream {}
A file output stream is an output stream for writing data to a File or to a FileDescriptor.
读文件 FileInputStream?
//FileInputStream 读raw bytes,如果要读字符流有使用FileReader
A FileInputStream obtains input bytes from a file in a file system.
FileInputStream is meant for reading streams of raw bytes such as image data.
For reading streams of characters, consider using FileReader
InputStream in = new FileInputStream(new File(filePath));
Reader
/* Abstract class for reading character streams.*/
public abstract class Reader implements Readable, Closeable {}
BufferReader
/**
* Reads text from a character-input stream, buffering characters so as to
* provide for the efficient reading of characters, arrays, and lines.
*/
public class BufferedReader extends Reader {}
StringBuffer
/**
* A thread-safe, mutable sequence of characters.[可变的字符序列]
* A string buffer is like a {@link String}, but can be modified. At any
* point in time it contains some particular sequence of characters, but
* the length and content of the sequence can be changed through certain
* method calls.
*/
public final class StringBuffer extends AbstractStringBuilder
implements java.io.Serializable, CharSequence
{}
//5.1 获得conn的InputStream 和要写入文件的outStream
inStream = conn.getInputStream();
File aimFile = new File(folder, fileNameString);
outStream = new FileOutputStream(aimFile);
//5.2 循环从InputStream 读到数据写入到 outStream
byte[] buffer = new byte[1024];
int len = 0;
while ((len = inStream.read(buffer)) != -1) {// inputStream的读函数
outStream.write(buffer, 0, len);// 向outputStream里写入
}
Log.i(TAG, "please check file of tmp.config exit or not");
return aimFile;