处理流_Buffered缓冲流

Buffered缓冲流

示例代码：

/**
 * 缓冲流的使用
 * 1.缓冲流
 * BufferedInputStream
 * BufferedOutputStream
 * BufferedReader
 * BufferedWriter
 *
 * 2。作用:提高读取和写入的速度
 *  提高速度的原因：内部提供了一个缓冲区
 *
 * 3. 处理流就是套接在已有的流的基础上
 */
public class BufferedTest {
  /*
  实现非文本文件的复制
   */
  public static void main(String[] args) {
    BufferedInputStream bufferedInputStream = null;
    BufferedOutputStream bufferedOutputStream = null;
    try {
      //1.造文件
      File src = new File("基础语法\沙滩.jpg");
      //System.out.println(src.getAbsolutePath());
      File dest = new File("基础语法\沙滩3.jpg");
      //2.造流
      //2.1 节点流
      FileInputStream fileInputStream = new FileInputStream(src);
      FileOutputStream fileOutputStream = new FileOutputStream(dest);
      //2.2处理流(缓冲流)
      bufferedInputStream = new BufferedInputStream(fileInputStream);
      bufferedOutputStream = new BufferedOutputStream(fileOutputStream);
      //3.复制的细节  读取 写入
      byte[] buffer = new byte[10];
      int  len;
      while ((len = bufferedInputStream.read(buffer)) != -1){
        bufferedOutputStream.write(buffer,0,len);
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      try {
        if (bufferedOutputStream != null)
          bufferedOutputStream.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
      try {
        if (bufferedInputStream != null)
          bufferedInputStream.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
    //4.资源关闭
    //要求：先关闭外层流 再关闭内层流
    //说明：在关闭外层流时，内层流会自动关闭  内层流的关闭可以省略
//    fileInputStream.close();
//    fileOutputStream.close();
  }
}

/**
 * 缓冲流的使用
 * 1.缓冲流
 * BufferedInputStream
 * BufferedOutputStream
 * BufferedReader
 * BufferedWriter
 *
 * 2。作用:提高读取和写入的速度
 *  提高速度的原因：内部提供了一个缓冲区
 *
 * 3. 处理流就是套接在已有的流的基础上
 */
public class BufferedTest {
  /*
  实现文本文件的复制
   */
  public static void main(String[] args) {
    BufferedReader bufferedReader = null;
    BufferedWriter bufferedWriter = null;
    try {
      //创建文件和对应的流
      bufferedReader = new BufferedReader(new FileReader(new File("基础语法\a.txt")));
      bufferedWriter = new BufferedWriter(new FileWriter(new File("基础语法\d.txt")));
      //读写文件
//      //方式一
//      char[] buffer = new char[1024];
//      int len;
//      while ((len = bufferedReader.read(buffer)) != -1){
//        bufferedWriter.write(buffer,0,len);
      //方式二
      String data;
      while ((data = bufferedReader.readLine()) != null){
        //方法一
//        bufferedWriter.write(data+ "
"); //data中不包含换行符  只有一行
        //方法二
        bufferedWriter.write(data);//data中不包含换行符
        bufferedWriter.newLine();  //提供换行操作
      }
    } catch (IOException e) {
      e.printStackTrace();
    } finally {
      //关闭资源
      try {
        if (bufferedReader!= null)
        bufferedReader.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
      try {
        if (bufferedWriter != null)
        bufferedWriter.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }
}

练习_图片的加密解密

加密：

public class PicSecret {
    //图片加密
    public static void main(String[] args) {
        FileInputStream fileInputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            fileInputStream = new FileInputStream("基础语法\沙滩.jpg");
            fileOutputStream = new FileOutputStream("基础语法\沙滩secret.jpg");
            byte[] buffer = new byte[20];
            int len;
            while ((len = fileInputStream.read(buffer)) != -1){
                //对字节数据进行修改 进行加密操作
                for (int i = 0; i <len ; i++) {
                    buffer[i] = (byte) (buffer[i] ^ 5);
                }
                fileOutputStream.write(buffer,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {

            try {
                if (fileInputStream != null)
                fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (fileOutputStream != null)
                fileOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

解密：

public class PicSecretFree {
    //图片解密
    public static void main(String[] args) {
        FileInputStream fileInputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            fileInputStream = new FileInputStream("基础语法\沙滩secret.jpg");
            fileOutputStream = new FileOutputStream("基础语法\沙滩secretfree.jpg");

            byte[] buffer = new byte[20];
            int len;
            while ((len = fileInputStream.read(buffer)) != -1){
                //对字节数据进行修改 进行加密操作
                for (int i = 0; i <len ; i++) {
                    buffer[i] = (byte) (buffer[i] ^ 5);
                }
                fileOutputStream.write(buffer,0,len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                if (fileInputStream != null)
                    fileInputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (fileOutputStream != null)
                    fileOutputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

练习_获取文本中每个字符出现的次数

public class WordCount {
    //获取文本中每个字符出现的次数
    public static void main(String[] args) {
        BufferedReader bufferedReader = null;
        BufferedWriter bufferedWriter = null;
        try {
            bufferedReader = new BufferedReader(new FileReader("基础语法\a.txt"));
            bufferedWriter = new BufferedWriter(new FileWriter("基础语法\x.txt"));
            //创建Map集合
            Map<Character,Integer> map = new HashMap<>();
            //遍历每一个字符，每一个字符出现的次数放到Map里面
            int len;
            while ((len = bufferedReader.read()) != -1){
                //int 还原成 char
                char ch = (char) len;
                //判断是否是第一次出现
                if (map.get(ch) == null ){
                    map.put(ch,1);
                }else {
                    map.put(ch,map.get(ch)+1);
                }
            }
            //把Map中的数据存在文件x.txt中   遍历Map  再写入数据
            for (Map.Entry<Character,Integer> entry:map.entrySet()){
                switch (entry.getKey()){
                    case ' ':
                        bufferedWriter.write("空格="+entry.getValue());
                        break;
                    case '	':
                        bufferedWriter.write("tab键="+entry.getValue());
                        break;
                    case '
':
                        bufferedWriter.write("换行"+entry.getValue());
                        break;
                    case '
':
                        bufferedWriter.write("回车"+entry.getValue());
                        break;
                    default:
                        bufferedWriter.write(entry.getKey()+"="+entry.getValue());
                        break;
                }
                bufferedWriter.newLine();
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {

            try {
                if (bufferedReader != null)
                bufferedReader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            try {
                if (bufferedWriter != null)
                bufferedWriter.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }
}