OutputStream、InputStream是所有字节流的超类，所谓字节流就是一个字节一个字节的读取，类似于c中的二进制读取方法
java.io.OutputStream
Method
void write(int b)
Writes the specified byte to this output stream
void write(byte[] b) // String 类的方法， byte[] b = "中国".getBytes();
Writes b.length bytes from the specified byte array to this output stream.
void write(byte[], int offset, int len)
Writes len bytes from the specified byte array starting at offset off to this output stream.
OutputStream out = new FileOutputStream("E:/a.txt"); out.write(97); // 写下二进制的97，文本编辑器读出二进制97，查询本机编码表，得出a byte[] b = {-43,-44}; // 赵 out.write(b); out.close(); void flush()
Flushes this output stream and forces any buffered output bytes to be written out.
void close()
子类 FileOutputStream
构造函数
FileOutputStream(File file, boolean append) // append 参数不写默认为false，即每次都会创建一个新文件（不管文件是否存在）
Creates a file output stream to write to the file represented by the specified File object.
FileOutputStream(String name, boolean append) // @name the file path @append 同上
其余方法暂时略，大部分与父类相同
java.io.InputStream
int read()
Reads the next byte of data from the input stream
int read(byte[] b)
Reads some number of bytes from the input stream and stores them into the buffer array b.
int read(byte[] b, int off, int len)
Reads up to len bytes of data from the input stream into an array of bytes.
InputStream in = new FileInputStream("E:/a.txt"); //文件内容 abcde //int a = in.read(); // 97 byte[] b = new byte[2]; int a = in.read(b); // a值 2 b值 ab a = in.read(b); // a值 2 b值 cd a = in.read(b); // a值 1 b值 ed a = in.read(b); // a值 -1 b值 ed // a 为读出的字节数， 读到文件末尾时为 -1 in.close(); 子类 FileInputStream
构造函数
FileInputStream(File file, boolean append)
FileInputStream(String name, boolean append) // 同上
二进制文件复制
InputStream in = new FileInputStream("E:/test.avi"); OutputStream out = new FileOutputStream("E:/copy.avi"); int len; byte[] b = new byte[1024]; while((len = in.read(b)) != -1) { out.write(b, 0, len); // out.flush(); } in.close(); out.close(); BufferedOutputStream、BufferedInputStream 提高程序读取效率
构造函数 BufferedOutputStream(OutputStream out)
下面是一个对比，复制102M的文件耗时
public static void copy_4(String desPath, String srcPath) throws IOException{ BufferedInputStream in = new BufferedInputStream(new FileInputStream(srcPath)); BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(desPath)); int len; byte[] b = new byte[1024]; while((len = in.read(b)) != -1) { out.write(b, 0, len); } in.close(); out.close();}/* * 一个字节一个的读，没缓冲 408,891 * 一个字节一个的读,有缓冲 4979 * 每次读 1024字节， 没缓冲 898 * 每次读 1024字节， 有缓冲 236 */