I/O流

流的分类

1. 操作数据单位：字节流、字符流
2. 数据的流向：输入流、输出流
3. 流的角色：节点流、处理流

   流的体系结构

字符流输入且输出

File file = new File("hello.txt");
        File filecopy = new File("hello1.txt");
        FileReader in = null;
        FileWriter out = null;
        try {
            char[] cur = new char[5];
            int len;
           //构造器true,不会覆盖
            out = new FileWriter(filecopy,true);
            in = new FileReader(file);
            while((len = in.read(cur))!=-1){
                out.write(cur,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            if(out!=null){
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(in!=null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

字节流输入输出

File file = new File("q.png");
        File filecopy = new File("q1.png");
        FileInputStream in = null;
        FileOutputStream out = null;
        try {
            //构造器true,不会覆盖
            byte[] cur = new byte[5];
            int len;
            out = new FileOutputStream(filecopy,true);
            in = new FileInputStream(file);
            while((len = in.read(cur))!=-1){
                out.write(cur,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally{
            if(out!=null){
                try {
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(in!=null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

处理流之一缓存流

提高流的读写速度,原因：内部提供了一个缓存区

1. 代码

   //造文件
        File srcfile = new File("1.png");
        File destfile = new File("2.png");
        BufferedInputStream bis = null;
        BufferedOutputStream bos = null;
        try {
            //造流
            //造节点流
            FileInputStream fis = new FileInputStream(srcfile);
            FileOutputStream fos = new FileOutputStream(destfile);
            //造缓冲流
            bis = new BufferedInputStream(fis);
            bos = new BufferedOutputStream(fos);
            //复制的细节：读取、写入
            byte[] buffer = new byte[1024];
            int len;
            while((len = bis.read(buffer))!=-1){
                bos.write(buffer,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(bis!=null){
                try {
                    bis.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(bos!=null){
                try {
                    bos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }

   处理流的一种：转换流

读取UTF-8

InputStreamReader isr = null;
        try {
            FileInputStream fis = new FileInputStream("UT8-8.TXT");
            isr = new InputStreamReader(fis, "UTF-8");
            char[] cbuf = new char[20];
            int len;
            while((len=isr.read(cbuf))!=-1){
                for(int i =0;i<cbuf.length;i++){
                    System.out.println(cbuf[i]);
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            if(isr!=null){
                try {
                    isr.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }