java中的io流分为两类，字符和字节：
class useByteStream
{
/**
* 使用文件输出字节流
*
*/
public static void testFileOutputStream()
{
OutputStream out = null;
try
{
File f = new File(".\\log\\test.txt");
//out = new FileOutputStream(f);
out = new FileOutputStream(f,true); //追加方式记录到文件
String str = "Hello World!!!";
byte b[] = str.getBytes();
out.write(b);
out.close();
}
catch(FileNotFoundException e)
{
}
catch(IOException e)
{
}
}
/**
* 使用文件输入字节流
*/
public static void testFileInputStream()
{
InputStream out = null;
try
{
File f = new File(".\\log\\test.txt");
out = new FileInputStream(f);
String str = "Hello World!!!";
byte b[] = new byte[1000];
int len = out.read(b);
System.out.println(new String(b,0, len) );
out.close();
}
catch(FileNotFoundException e)
{
}
catch(IOException e)
{
}
}
};class useCharStream
{
/**
* 使用文件字符输出流
*/
public static void testFileWriter()
{
Writer w = null;
try
{
File f = new File(".\\log\\test2.txt");
w = new FileWriter(f,true); //追加方式
w.write("hello world\r\n");
w.close();
}
catch(FileNotFoundException e)
{
e.printStackTrace();
}
catch(IOException e)
{
e.printStackTrace();
}
}
/**
* 使用文件字符输入流
*/
public static void testFileReader()
{
Reader w = null;
try
{
File f = new File(".\\log\\test2.txt");
w = new FileReader(f);
char c[] = new char[1024];
w.read(c);
System.out.println(c);
w.close();
}
catch(FileNotFoundException e)
{
e.printStackTrace();
}
catch(IOException e)
{
e.printStackTrace();
}
}
};以上都是基于文件流操作，接下来是基于内存操作流，如果只是写业务代码应该很少会用到。
class useMemoryStream
{
/**
* 使用内存操作流,字节
*/
public static void testByteArray()
{
String str = "Hello world";
ByteArrayInputStream bis = null;
ByteArrayOutputStream bos = null;
bis = new ByteArrayInputStream(str.getBytes());
bos = new ByteArrayOutputStream();
int temp =0;
while((temp=bis.read())!=-1)
{
char c = (char)temp;
bos.write(Character.toUpperCase(c));
}
String newStr = bos.toString();
try
{
bis.close();
bos.close();
}
catch(IOException e)
{
e.printStackTrace();
}
System.out.println(newStr);
}
};class Send implements Runnable
{
private PipedOutputStream pos = null;
public Send()
{
this.pos = new PipedOutputStream();
}
public void run()
{
String str = "Hello world!!!";
try
{
try
{
Thread.sleep(2000);
}
catch(InterruptedException e)
{
e.printStackTrace();
}
this.pos.write(str.getBytes());
System.out.println("thread:"+Thread.currentThread().getId()+",Send string:"+str);
}
catch(IOException e)
{
e.printStackTrace();
}
try
{
this.pos.close();
}
catch(IOException e)
{
e.printStackTrace();
}
}
public PipedOutputStream getPos()
{
return this.pos;
}
};
class Receive implements Runnable
{
private PipedInputStream pis = null;
public Receive()
{
this.pis = new PipedInputStream();
}
public void run()
{
byte b[] = new byte[1024];
int len =0;
try
{
len = this.pis.read(b); //阻塞方式
}
catch(IOException e)
{
e.printStackTrace();
}
try
{
pis.close();
}
catch(IOException e)
{
e.printStackTrace();
}
System.out.println("thread:"+Thread.currentThread().getId()+",receive:"+new String(b,0,len));
}
public PipedInputStream getPis()
{
return this.pis;
}
};
class pipedTest
{
public void pipedStream()
{
Send s = new Send();
Receive r = new Receive();
try {
s.getPos().connect(r.getPis());
}
catch(IOException e)
{
e.printStackTrace();
}
new Thread(r).start();
new Thread(s).start();
}
};以上都是无缓存的，考虑到一般场景下，提高使用性能，最好使用有缓存的字符流：BufferedReader和BufferedWriter。
BufferedReader
只能接受输入为字符流，不能为字节流。所以有时候会使用InputStreamReader来转换字节流给字符流使用。还有BufferedWriter
class useBuffer
{
public static void testBufferReader()
{
BufferedReader buf = null;
//此处用到了字节流转字符流的类InputStreamReader，这是因为BufferedReader只能接收字符流
buf = new BufferedReader(new InputStreamReader(System.in));
String str =null;
try
{
str = buf.readLine();
}
catch(IOException e)
{
e.printStackTrace();
}
System.out.println("输出的内容为："+str);
}
public static void testBufferWriter()
{
File f = new File(".\\log\\test2.txt");
try {
//默认缓冲区大小 8K 可以通过 new BufferedWriter(new FileWriter(f),1024);指定大小为1K
BufferedWriter out =new BufferedWriter(new FileWriter(f));
out.write("123321123355555", 0, 10);
out.write("\r\n");
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
};SCanner类，输入数据类。
使用方法和BufferedReader类类似，并且方便验证数据类型。
class useScan
{
public static void testScan()
{
Scanner scan = new Scanner(System.in);
//以回车作为输入的结束符号，否则默认是空格
scan.useDelimiter("\r\n");
if(scan.hasNextInt()==true)
{
int str = scan.nextInt();
System.out.println("int "+str);
}
else
{
String str = scan.next();
System.out.println("string "+str);
}
}
};scan.hasNext支持正则表达式。比如 hasNext("^\\d{4}-\\d{2}-\\d{2}$") 就是日期格式yyyy-MM-dd的正则表达式，通过next("^\\d{4}-\\d{2}-\\d{2}$")。
免责声明：本站发布的内容（图片、视频和文字）以原创、转载和分享为主，文章观点不代表本网站立场，如果涉及侵权请联系站长邮箱：is@yisu.com进行举报，并提供相关证据，一经查实，将立刻删除涉嫌侵权内容。
