【Java基础总结】IO流

字节流

1. InputStream 字节输入流

代码演示

    InputStream in = System.in;
    
    System.out.println("int read(byte b) 方法演示");
    //int read()
    int bt = 0;
    while((bt=in.read())>0){    
        System.out.print(bt+" ");
        if(bt == 10){    //回车
(13) 换行
(10)
            break;
        }
    }
    System.out.println("

int read(byte[] buffer) 方法演示");

    //int read(byte[] buffer)
    int length = 0;
    byte[] buffer = new byte[10];
    while((length=in.read(buffer)) != 0){
        for(int i=0; i<length; i++){
            System.out.print(buffer[i]+" ");
        }
        break;
    }
    
    System.out.println("

int read(byte[] buffer, int offset, int len) 方法演示");
    
    //int read(byte[] buffer, int offset, int len)
    int len = 1024;
    int count = 0;
    byte[] buf = new byte[len];
    while((count=in.read(buf, 0, len))>0){
        for(int i=0; i<count; i++){
            System.out.print(buf[i]+" ");
        }
        break;
    }
    in.close();

2. OutputStream 字节输出流

 

代码演示

    OutputStream out = System.out;
    //void write(int b)
    out.write(65);    //字符A
    
    out.write(13);    //回车 

    out.write(10);    //换行 

    
    //flush()
    out.flush();
    
    //write(byte[] bytes)
    byte[] bytes = new String("张晓明").getBytes();
    out.write(bytes);
    
    out.write(13);    //回车 

    out.write(10);    //换行 

    
    //write(byte[] bytes, int offset, int length)
    bytes = new String("zhangxiaoming").getBytes();
    out.write(bytes, 5, 8);
    
    out.close();

字符流

1. Reader 字符输入流

代码演示

    Reader reader = new InputStreamReader(System.in);
    
    //int read()
    System.out.println("int read() 方法演示");
    int c;
    while((c=reader.read()) != 13){
        System.out.print((char)c);
    }
    reader.read();
    
    //int read(char[] buf)
    System.out.println("

int read(char[] buf) 方法演示");
    int count = 0;
    char[] buf = new char[1024];
    while((count=reader.read(buf)) > 0){
        String str = new String(buf, 0, count);
        if(str.indexOf("stop")>=0) break;
        System.out.print(str);
    }
    
    //int read(char[] buffer, int offset, int len)
    System.out.println("

int read(char[] buffer, int offset, int len) 方法演示");
    int length = 1024;
    char[] buffer = new char[length];
    while((count=reader.read(buffer, 0, length)) > 0){
        String str = new String(buffer, 0, count);
        if(str.indexOf("stop")>=0) break;
        System.out.print(str);
    }

2. Writer 字符输出流

 

代码演示

    Writer writer = new OutputStreamWriter(System.out);
    String str = "中国";
    
    //write(String str) 写入字符串
    writer.write(str);
    
    //write(int c)    写入单个字符
    writer.write(10);    //换行符
    
    //write(String str, int offset, int length) 写入部分字符串
    writer.write(str, 0, 1);
    
    writer.write(10);
    
    //write(char[] buf)    写入字符数组
    char[] chars = str.toCharArray();
    writer.write(chars);
    
    writer.write(10);
    
    //write(char[] buf, int offset, int length) 写入部分字符数组
    writer.write(chars, 0, 1);
    writer.write(10);
    
    writer.flush();
    
    //append(char c) 追加字符
    writer.append('z');
    writer.write(10);
    
    String str2 = "中华人民共和国";
    //append(CharSequence csq)
    writer.append(str2);
    writer.write(10);
    
    //append(CharSequence csq, int offset, int length)
    writer.append(str2, 0, 4);
    
    writer.close();