/**
*
* 在Java IO中，流是一个核心的概念。
* 流从概念上来说是一个连续的数据流。
* 既可以从流中读取数据，也可以往流中写数据。
* 流与数据源或者数据流向的媒介相关联。
* 在Java IO中流既可以是字节流(以字节为单位进行读写)，也可以是字符流(以字符为单位进行读写)。
*/
public class JavaIoTest {
/**
* 字节流对应的类应该是InputStream和OutputStream
*
* @throws IOException
*/
public static void writeByteToFile() throws IOException {
String hello = "hello world";
byte[] bytes = hello.getBytes();
File file = new File("/Users/grug/test.txt");
//字节流写,用outPutStream,写文件用FileOutPutStream
OutputStream os = new FileOutputStream(file);
os.write(bytes);
os.close();
}
public static void readByteFromFile() throws IOException {
File file = new File("/Users/grug/test.txt");
byte[] fileByte = new byte[(int) file.length()];
InputStream inputStream = new FileInputStream(file);
//buffer 可以提高读取速度,比inputStream 一个一个字节读要快
BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream, 2 * 1024);
// inputStream.read(fileByte);
bufferedInputStream.read(fileByte);
System.out.println(new String(fileByte));
inputStream.close();
}
/**
* 字符流对应的类应该是Reader和Writer
*
* @throws IOException
*/
public static void writeCharToFile() throws IOException {
String hello = "hello world";
File file = new File("/Users/grug/writeCharToFile_test.txt");
//字符流写文件
Writer fileWrite = new FileWriter(file);
fileWrite.write(hello);
fileWrite.close();
}
public static void readCharFromFile() throws IOException {
File file = new File("/Users/grug/writeCharToFile_test.txt");
Reader reader = new FileReader(file);
//用buffer提高读取速度,可以指定每次读取的大小
BufferedReader bufferedReader = new BufferedReader(reader, 2 * 1024);
char[] chars = new char[(int) file.length()];
bufferedReader.read(chars);
String result = new String(chars);
System.out.println(result);
}
/**
* 管道主要用来实现同一个虚拟机中的两个线程进行交流
*
* @throws IOException
*/
public static void pipedStream() throws IOException {
final PipedOutputStream pipedOutputStream = new PipedOutputStream();
final PipedInputStream pipedInputStream = new PipedInputStream(pipedOutputStream);
Thread thread1 = new Thread(new Runnable() {
@Override
public void run() {
try {
pipedOutputStream.write("hello pipe".getBytes());
} catch (IOException e) {
e.printStackTrace();
}
}
});
Thread thread2 = new Thread(() -> {
try {
byte[] dataByte = new byte[10];
pipedInputStream.read(dataByte);
System.out.println(new String(dataByte));
} catch (IOException ex) {
try {
pipedInputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
});
thread1.start();
thread2.start();
}
/**
* 字节流可以转换成字符流，
*
* @throws IOException
*/
public static void convertBytesToChars() throws IOException {
File file = new File("/Users/grug/test.txt");
InputStream inputStream = new FileInputStream(file);
Reader fileRead = new InputStreamReader(inputStream);
char[] chars = new char[(int) file.length()];
fileRead.read(chars);
String result = new String(chars);
System.out.println(result);
}
public static void main(String[] args) {
try {
pipedStream();
} catch (IOException ex) {
ex.printStackTrace();
}
}
}
