java文件流对象

package com.alibaba.caseutils.test;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public class INputAndOut {
    public static void main(String[] args) {
        String path="src\\test\\java\\read.txt";
        InputStream inputStream = null;
        try {
             inputStream =new FileInputStream ( path );
             for(;;){//for循环的死循环写法
                 int n =inputStream.read ();
                 if(n==-1){//当满足特定的条件时退出
                     break;
                 }
                 System.out.println (n);
             }
        } catch (Exception e) {
            e.printStackTrace ();
        }finally {
            if(inputStream !=null){
                try {
                    inputStream.close ();
                } catch (IOException e) {
                    e.printStackTrace ();
                }
            }
        }
    }
}

229
191
151

==========================================================================

 用FileInputStream可以从文件获取输入流，这是InputStream常用的一个实现类。此外，ByteArrayInputStream可以在内存中模拟一个InputStream：

范例：

package com.alibaba.caseutils.test;

import java.io.*;

public class INputAndOut {
    public static void main(String[] args) {
        byte[] bytes={11,22,127,44,-128,127};
        try {
            InputStream inputStream = new ByteArrayInputStream ( bytes );
            try {
                int n;
                for (; ; ) {
                    n = inputStream.read ();
                    if (n == -1) {
                        break;
                    }
                    System.out.println ( n );
                    System.out.println ((char)n);
                }
            } finally {
                inputStream.close ();
            }
        } catch (IOException e) {
            e.printStackTrace ();
        }
    }
}

 

package com.alibaba.caseutils.test;

import java.io.*;

public class INputAndOut {
    public static void main(String[] args) {
        byte[] bytes={11,22,127,44,-128,127};
        InputStream inputStream = new ByteArrayInputStream (bytes);

        while (true){
            try {
                int len = 0;
                while ((-1 != (len =inputStream.read () ))){
                    int n=inputStream.read ();
                    System.out.println (n);
                }
            } catch (IOException e) {
                e.printStackTrace ();
            }
        }


    }
}

 

 

 

 

 

 

 

上图是一个字节一个字节读取，而第二个图是安装字节数组读取，返回的是读取的数组个数 对应的方法

 

 

 读取文件

 

package com.alibaba.caseutils.test;

import java.io.*;

public class JavaApidemo {
    public static void main(String[] args) {
        File file =new File ( "D:"+File.separator+"czq"+File.separator+"zq.txt" );
        if(!file.getParentFile ().exists ()){
            file.getParentFile ().mkdir ();
        }
        OutputStream outputStream = null;
        try {
            outputStream = new FileOutputStream ( file ,true);
            String str="Hello world\r\n";
            outputStream.write ( str.getBytes () );
        }catch (Exception e){
            e.printStackTrace ();
        }
    }


}

 

 

 

 

 

package com.alibaba.autotest_v2;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class Inputinter {
    
    public static void main(String[] args) throws Exception {
        String AA ="HELLO";
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(AA.getBytes());  //将数据写入内存缓冲区
        ByteArrayOutputStream byteArrayOutputStream =new ByteArrayOutputStream();//创建从内存缓冲区读取流对象
        int lenth;
        while ((lenth=byteArrayInputStream.read()) != -1) {
            byteArrayOutputStream.write(lenth);   //保存数据
        }
        byte[] bytes= byteArrayOutputStream.toByteArray();
        System.out.println(new String(bytes));

    }
}

 补充

 内存流读取原理图

 

 文件流读写终端