java基础——包装流

缓冲流Buffered

package stream;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import org.junit.jupiter.api.Test;

/*
 * 1.缓冲流
 * BufferedInputStream
 * BufferedOutputStream
 * BufferedReader
 * BufferedWriter
 * 把读写流用缓冲流包装起来就行
 * 
 * 2.作用：提高流的读取写入速度
 * 
 * */

public class BufferedTest {
    
    /*
     *     实现非文本文件的赋值
     * */
    @Test
    public void BufferedStreamTest(){
        BufferedInputStream brs = null;
        BufferedOutputStream bos = null;
        try {
            File sfile = new File("zsben.jpg");
            File tfile = new File("zsben3.jpg");
            
            FileInputStream fis = new FileInputStream(sfile);
            FileOutputStream fos = new FileOutputStream(tfile);

            //用缓冲流包装读写流
            brs = new BufferedInputStream(fis);
            bos = new BufferedOutputStream(fos);
            
            byte[] buffer = new byte[10];
            int len;
            while((len = brs.read(buffer))!=-1) {
                bos.write(buffer,0,len);
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        finally {
            try {
                //关闭外层流的同时， 内层流也会自动被关闭
                brs.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
            try {
                bos.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        
    }
}
  

转换流

package stream;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;

import org.junit.jupiter.api.Test;

/*
 *     处理流之二：转换流 
 *         OutputStreamWriter：字符输出流->字节输出流
 *         InputStreamWriter：字节输入流->字符输入流  
 *         
 *    字符->字节 ('a'->97)：即一个编码过程
 *          字节->字符 (97->'a')：即一个解码过程
 *       
 *     发送过程时先把字符码转换成字节码进行发送，
 *     接收方接受时把字节码转换成字符码
 * */
 
public class InputStreamReaderITest {
    @Test
    public void test1() throws IOException {
        //第二个参数：file保存时使用的编码方式
        InputStreamReader isr= null;
        try {
            File file = new File("hello.txt");
            FileInputStream fis = new FileInputStream(file);
            
            //字节流->字符流，注意后面的参数要带上编码方式，原来使用gbk编码存的，这儿换成UTF-8就会使中文字符乱码
            isr = new InputStreamReader(fis,"gbk");
            
            char [] buf = new char[20];
            int len;
            while((len = isr.read(buf))!=-1) {
                
                String s = new String(buf,0,len);
                System.out.println(s);
                
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
        isr.close();
    }
}