java字符流缓冲区详解

public class BufferedWriter extends Writer 

// 关闭此流，但要先刷新它，实际上调用了Writer类的close方法 
public void close() throws IOException 
// 刷新该流的缓冲 
public void flush() throws IOException 
// 写入一个行分隔符。行分隔符字符串由系统属性 line.separator 定义 
public void newLine() throws IOException 
// 写入字符数组的某一部分 
public void write(char[] cbuf, int off, int len) throws IOException 
// 写入单个字符 
public void write(int c) throws IOException 

public class BufferedReader extends Reader 

// 关闭该流并释放与之关联的所有资源 
public void close() throws IOException 
// 读取一个文本行。通过下列字符之一即可认为某行已终止：换行 ('\n')、回车 ('\r') 或回车后直接跟着换行 
public String readLine() throws IOException 
// 将字符读入数组的某一部分 
public int read(char[] cbuf, int off, int len) throws IOException 
// 读取单个字符 
public int read() throws IOException 

File source = new File("Demo.txt"); 
if (!source.exists()) { 
  return; 
} 
BufferedWriter bufferedWriter = null; 
BufferedReader bufferedReader = null; 
try { 
  bufferedReader = new BufferedReader(new FileReader(source)); 
  bufferedWriter = new BufferedWriter(new FileWriter("Demo_copy.txt")); 
  String line = null; 
  while ((line = bufferedReader.readLine()) != null) { 
    bufferedWriter.write(line); 
    bufferedWriter.newLine();  // 换行 
    bufferedWriter.flush();   //将缓冲区数据刷到指定文件中 
  } 
} catch (Exception e) { 
  throw new RuntimeException("文件复制失败！"); 
} finally { 
  // 关闭 bufferedWriter 和 bufferedReader 
} 

 public class MyBufferedRead extends Reader{ 
  /** 
   * 缓冲区在定义时被缓冲的流对象 
   */ 
  private Reader read; 
 
  private char[] buffer = new char[1024]; 
  // 用于记录存储到缓冲区中字符个数的变量 
  private int count = 0; 
  // 用于操作数据中元素的角标 
  private int pos = 0; 
 
  public MyBufferedRead(Reader read) { 
    this.read = read; 
  } 
 
  /** 
   * 定义一个读取方法，从缓冲区中读取一个字符 
   */ 
  public int myRead() throws IOException { 
    // 读取一批数据到缓冲数据buffer中 
    if (count == 0) { 
      count = read.read(); 
      pos = 0; 
    } 
 
    if (count < 0) 
      return -1; 
 
    char ch = buffer[pos]; 
    pos++; 
    count--; 
    return ch; 
  } 
 
  /** 
   * 定义一个读取一行的方法 
   */ 
  public String myReadLine() throws IOException { 
    StringBuilder stringBuilder = new StringBuilder(); 
    int ch = 0; 
    while ((ch = read.read()) != -1) { 
      // 如果遇到此字符，则继续 
      if (ch == '\r') { 
        continue; 
      } 
      // 如果遇到此字符，表示该行读取结束 
      if (ch == '\n') { 
        return stringBuilder.toString(); 
      } 
      // 将该行的字符添加到容器 
      stringBuilder.append((char) ch); 
    } 
    // 如果读取结束，容器中还有字符，则返回元素 
    if (stringBuilder.length() != 0) { 
      return stringBuilder.toString(); 
    } 
    return null; 
 
  } 
 
  /** 
   * 关闭缓冲区 
   */ 
  public void myClose() throws IOException { 
    read.close(); 
  } 
 
  @Override 
  public int read(char[] cbuf, int off, int len) throws IOException { 
    return 0; 
  } 
 
  @Override 
  public void close() throws IOException { 
  } 
} 

public class MyBufferedReadDemo { 
  /** 
   * BufferedReader 方式的read方法 
   */ 
  @Test 
  public void bufferedDemo() throws IOException{ 
    FileReader fileReader = new FileReader("JAVA专业术语集.txt"); 
    BufferedReader bufferedReader = new BufferedReader(fileReader); 
    int ch = 0; 
    while ((ch = bufferedReader.read()) != -1) { 
      System.out.print((char) ch); 
    } 
    // 关闭 bufferedReader 
    bufferedReader.close(); 
  } 
   
  /** 
   * 自定义MyBufferedRead类的myRead方法 
   */ 
  @Test 
  public void myBufferedDemo() throws IOException{ 
    FileReader fileReader = new FileReader("JAVA专业术语集.txt"); 
    MyBufferedRead myBufferedRead = new MyBufferedRead(fileReader); 
    int ch = 0; 
    while ((ch = myBufferedRead.myRead()) != -1) { 
      System.out.print((char) ch); 
    } 
    myBufferedRead.myClose(); 
  } 
   
  /** 
   * BufferedReader 方式的readLine方法 
   */ 
  @Test 
  public void readLineDemo() throws IOException{ 
  FileReader fileReader = new FileReader("JAVA专业术语集.txt"); 
    BufferedReader bufferedReader = new BufferedReader(fileReader); 
    String line = null; 
    while ((line = bufferedReader.readLine()) != null) { 
      System.out.println(line); 
    } 
    bufferedReader.close();    
  } 
   
  /** 
   * 自定义MyBufferedRead类的myReadLine方法 
   */ 
  @Test 
  public void myReadLineDemo() throws IOException{ 
    FileReader fileReader = new FileReader("JAVA专业术语集.txt"); 
    MyBufferedRead myBufferedRead = new MyBufferedRead(fileReader); 
    String line = null; 
    while ((line = myBufferedRead.myReadLine()) != null) { 
      System.out.println(line); 
    } 
    myBufferedRead.myClose();   
  } 
} 

public class LineNumberReaderextends BufferedReader 

FileReader fileReader = new FileReader("tempFile\\demo.java"); 
LineNumberReader lineNumberReader = new LineNumberReader(fileReader); 
String line = null; 
// 设置开始行号 
lineNumberReader.setLineNumber(10); 
while ((line = lineNumberReader.readLine()) != null) { 
  System.out.println(lineNumberReader.getLineNumber() + "\t" + line); 
} 
lineNumberReader.close();