Java 中的 BufferedWriter 介绍_动力节点Java学院整理

 // 构造函数 BufferedWriter(Writer out) BufferedWriter(Writer out, int sz) void  close()               // 关闭此流，但要先刷新它。 void  flush()               // 刷新该流的缓冲。 void  newLine()              // 写入一个行分隔符。 void  write(char[] cbuf, int off, int len) // 写入字符数组的某一部分。 void  write(int c)             // 写入单个字符。 void  write(String s, int off, int len)  // 写入字符串的某一部分。 

 package java.io; public class BufferedWriter extends Writer { // 输出流对象 private Writer out; // 保存“缓冲输出流”数据的字符数组 private char cb[]; // nChars 是cb缓冲区中字符的总的个数 // nextChar 是下一个要读取的字符在cb缓冲区中的位置 private int nChars, nextChar; // 默认字符缓冲区大小 private static int defaultCharBufferSize = ; // 行分割符 private String lineSeparator; // 构造函数，传入“Writer对象”，默认缓冲区大小是k public BufferedWriter(Writer out) { this(out, defaultCharBufferSize); } // 构造函数，传入“Writer对象”，指定缓冲区大小是sz public BufferedWriter(Writer out, int sz) { super(out); if (sz <= 0) throw new IllegalArgumentException("Buffer size = nChars) flushBuffer(); cb[nextChar++] = (char) c; } } // 返回a，b中较小的数 private int min(int a, int b) { if (a <b) return a; return b; } // 将字符数组cbuf写入到缓冲中，从cbuf的off位置开始写入，写入长度是len。 public void write(char cbuf[], int off, int len) throws IOException { synchronized (lock) { ensureOpen(); if ((off  cbuf.length) || (len  cbuf.length) || ((off + len) = nChars) { /* If the request length exceeds the size of the output buffer, flush the buffer and then write the data directly. In this way buffered streams will cascade harmlessly. */ flushBuffer(); out.write(cbuf, off, len); return; } int b = off, t = off + len; while (b = nChars) flushBuffer(); } } } // 将字符串s写入到缓冲中，从s的off位置开始写入，写入长度是len。 public void write(String s, int off, int len) throws IOException { synchronized (lock) { ensureOpen(); int b = off, t = off + len; while (b = nChars) flushBuffer(); } } } // 将换行符写入到缓冲中 public void newLine() throws IOException { write(lineSeparator); } // 清空缓冲区数据 public void flush() throws IOException { synchronized (lock) { flushBuffer(); out.flush(); } } public void close() throws IOException { synchronized (lock) { if (out == null) { return; } try { flushBuffer(); } finally { out.close(); out = null; cb = null; } } } }

 import java.io.BufferedWriter; import java.io.File; import java.io.OutputStream; import java.io.FileWriter; import java.io.IOException; import java.io.FileNotFoundException; import java.lang.SecurityException; import java.util.Scanner; /** * BufferedWriter 测试程序 * * */ public class BufferedWriterTest { private static final int LEN = 5; // 对应英文字母“abcdefghijklmnopqrstuvwxyz” //private static final char[] ArrayLetters = "abcdefghijklmnopqrstuvwxyz"; private static final char[] Arr<mark style="color:transparent">来源gaodaimacom搞#代%码网</mark>ayLetters = new char[] {'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'}; public static void main(String[] args) { testBufferedWriter() ; } /** * BufferedWriter的API测试函数 */ private static void testBufferedWriter() { // 创建“文件输出流”对应的BufferedWriter // 它对应缓冲区的大小是16，即缓冲区的数据>=16时，会自动将缓冲区的内容写入到输出流。 try { File file = new File("bufferwriter.txt"); BufferedWriter out = new BufferedWriter( new FileWriter(file)); // 将ArrayLetters数组的前10个字符写入到输出流中 out.write(ArrayLetters, 0, 10); // 将“换行符\n”写入到输出流中 out.write('\n'); out.flush(); //readUserInput() ; out.close(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (SecurityException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } /** * 读取用户输入 */ private static void readUserInput() { System.out.println("please input a text:"); Scanner reader=new Scanner(System.in); // 等待一个输入 String str = reader.next(); System.out.printf("the input is : %s\n", str); } }