[javase]IO

一、流

java流分为两种，一种字节流，另一种是字符流，分别由四个抽象类表示：InputStream, OutputStream, Reader, Writer

注：在网络程序设计中到底是使用字符流还是字节流呢？
答案：有一个简单的判断方法：如果通讯的双方都是java语言编写，最好使用字符流或更高级的流类。如果通讯的另一端是未知的，最好使用字节流，并事先约定好通讯规则发送和接收数据

1、输出流







FileOutputStream使用的2种方法

//1.创建文件
File file = new File("d:\\test.txt");
FileOutputStream fos = new FileOutputStream(file);
//		FileOutputStream fos = new FileOutputStream("d:\\test.txt", true);

//2.写入内容
byte[] b = "xiaoming a".getBytes();
fos.write(b);

//3.销毁流
fos.close();

ByteArrayOutputStream使用方法

public void byteArrayOutputStream() throws IOException {
int a = 0;
int b = 1;
int c = 2;
ByteArrayOutputStream bout = new ByteArrayOutputStream();
bout.write(a);
bout.write(b);
bout.write(c);
byte[] buff = bout.toByteArray();
for (int i = 0; i < buff.length; i++) {
System.out.println(buff[i]);
}

System.out.println("***********************");

ByteArrayInputStream bin = new ByteArrayInputStream(buff);
while ((b = bin.read()) != -1) {
System.out.println(b);
}
}

FilterOutputStream之BufferedOutputStream

@Test
public void filterOutputTest() {

FileOutputStream fos = null;
BufferedOutputStream bos = null;
try {
fos = new FileOutputStream("io.txt");
//1 BufferedOutputStream
//如果第二参数<=b.length+b1.length+b2.length或没有第二参数，缓存空间不够，会写入部分内容并bos.flush()
//否则b,b1,b2内容会缓存再bos里，等待bos.close或bos.flush
//如果bos.close()或者bos.flush()，会立即吸入io.txt
bos = new BufferedOutputStream(fos,16);

byte[] b = "小明".getBytes();
byte[] b1 = "大红".getBytes();
byte[] b2 = "小刚".getBytes();
bos.write(b);
bos.write(b1);
bos.write(b2);

} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (bos != null) {
bos.flush();
bos.close();
}
} catch (IOException e) {
e.printStackTrace();
}
}

}

Writer之BufferedWriter

@Test
public void bufferedWriterTest() throws IOException {

Writer w = null;
BufferedWriter bw = null;
try {
w = new FileWriter("io.txt");

bw = new BufferedWriter(w);

bw.write("sdsdafdasdfads");
bw.newLine();
bw.write("小明啊..............");

} catch (FileNotFoundException e) {
e.printStackTrace();
} finally {
if (bw != null) {
bw.flush();
bw.close();
}
}

}

Writer之OutputStreamWriter

@Test
public void outputStreamWriterTest() throws IOException {

OutputStreamWriter osw = new OutputStreamWriter(System.err);
BufferedWriter out
= new BufferedWriter(osw);

out.append("hello world").append("! 你好").append(", world");

System.out.println(osw.getEncoding());

out.flush();

}

1、输人流







InputStreamReader
读/写文件

//读/写文件
public void inputStreamReaderTest() throws Exception {

InputStreamReader isr = new InputStreamReader(new FileInputStream("d://catalina.out.2016-04-12-20.06.out"));

OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream("d://co.out"));

int i;
while ((i = isr.read()) != -1) {
osw.write(i);
}

osw.close();
isr.close();
}