Java之IO流詳解（三）——字符流-創(chuàng)新互聯(lián)

一、概述

Writer 是寫入字符流的抽象類。
OutputStreamWriter（OutputStream out）：輸出轉(zhuǎn)換流，創(chuàng)建使用默認(rèn)字符編碼的OutputStreamWriter。
OutputStreamWriter（OutputStream out, String charsetName）：創(chuàng)建使用指定字符編碼的OutputStreamWriter。
字符流的底層還是用字節(jié)流進(jìn)行讀寫的，字符流僅僅是做了字節(jié)和字符的轉(zhuǎn)換。
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Reader是用于讀取字符流的抽象類。
InputStreamReader(InputStream in)：輸入轉(zhuǎn)換流，創(chuàng)建默認(rèn)字符集的InputStreamReader。
InputStreamReader(InputStream in, String charsetName)：創(chuàng)建使用指定字符編碼的InputStreamReader。

二、字符流寫數(shù)據(jù)

字符流寫文本數(shù)據(jù)

方法	說明
publicvoid write(int c)	寫出一個字符
publicvoid write(char[] cbuf)	寫出字符數(shù)組
publicvoid write(char[] cbuf, int off, int len)	寫出字符數(shù)組cbuf中，從off開始，共len個字符
publicvoid write(String str)	寫出字符串
publicvoid write(String str, int off, int len)	寫出字符串，從off開始，共len個字符

eg:

//publicvoid write(int c) 寫出一個字符
public static void main(String[] args) {OutputStreamWriter outputStreamWriter = null;
    try {outputStreamWriter = new OutputStreamWriter(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test02.txt"), "UTF-8");
        outputStreamWriter.write('a');
        outputStreamWriter.write('b');
        outputStreamWriter.write('c');
        outputStreamWriter.write('貓');
    } catch (IOException e) {e.printStackTrace();
    } finally {if (outputStreamWriter != null) {try {outputStreamWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

//publicvoid write(char[] cbuf, int off, int len) 寫出字符數(shù)組cbuf中，從off開始，共len個字符
public static void main(String[] args) {OutputStreamWriter outputStreamWriter = null;
    try {outputStreamWriter = new OutputStreamWriter(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test02.txt"), "UTF-8");
        char[] chars = {'a','b','c','貓'};
        outputStreamWriter.write(chars,2,2);
    } catch (IOException e) {e.printStackTrace();
    } finally {if (outputStreamWriter != null) {try {outputStreamWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

//publicvoid write(char[] cbuf) 寫出字符數(shù)組
public static void main(String[] args) {OutputStreamWriter outputStreamWriter = null;
    try {outputStreamWriter = new OutputStreamWriter(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test02.txt"), "UTF-8");
        char[] chars = {'a','b','c','貓'};
        outputStreamWriter.write(chars);
    } catch (IOException e) {e.printStackTrace();
    } finally {if (outputStreamWriter != null) {try {outputStreamWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

//publicvoid write(String str) 寫出字符串
public static void main(String[] args) {OutputStreamWriter outputStreamWriter = null;
    try {outputStreamWriter = new OutputStreamWriter(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"),"UTF-8");
        outputStreamWriter.write("好好學(xué)習(xí)，天天向上");
    } catch (IOException e) {e.printStackTrace();
    }finally {if(outputStreamWriter != null){try {outputStreamWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

//publicvoid write(String str, int off, int len) 寫出字符串，從off開始，共len個字符
public static void main(String[] args) {OutputStreamWriter outputStreamWriter = null;
    try {outputStreamWriter = new OutputStreamWriter(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"),"UTF-8");
        outputStreamWriter.write("好好學(xué)習(xí)，天天向上", 4, 4);
    } catch (IOException e) {e.printStackTrace();
    }finally {if(outputStreamWriter != null){try {outputStreamWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

三、字符流讀數(shù)據(jù)

方法	說明
int read()	一次讀一個字符數(shù)據(jù)
int read(char[] cbuf)	一次讀一個字符數(shù)組數(shù)據(jù)

eg：

//int read() 一次讀一個字符數(shù)據(jù)
public static void main(String[] args) {InputStreamReader inputStreamReader = null;
    try {inputStreamReader = new InputStreamReader(new FileInputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"), "UTF-8");
        System.out.println((char)inputStreamReader.read());
        System.out.println((char)inputStreamReader.read());
        System.out.println((char)inputStreamReader.read());
    } catch (IOException e) {e.printStackTrace();
    }finally {if(inputStreamReader != null){try {inputStreamReader.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

//int read(char[] cbuf) 一次讀一個字符數(shù)組數(shù)據(jù)
public static void main(String[] args) {InputStreamReader inputStreamReader = null;
    try {inputStreamReader = new InputStreamReader(new FileInputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"),"UTF-8");
        char[] chars = new char[1024];
        int length;
        while ((length = inputStreamReader.read(chars)) != -1){System.out.println(new String(chars,0,length));
        }

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

四、字符流拷貝文本文件

eg:

public static void main(String[] args) {  InputStreamReader inputStreamReader = null;
	  OutputStreamWriter outputStreamWriter = null;
	  try {  inputStreamReader = new InputStreamReader(new FileInputStream("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"));
	      outputStreamWriter = new OutputStreamWriter(new FileOutputStream("C:\\Users\\Administrator\\Desktop\\test\\test02\\test01.txt"));
	      char[] chars = new char[1024];
	      int length;
	      while ((length = inputStreamReader.read(chars)) != -1){  outputStreamWriter.write(chars,0, length);
	      }
	  } catch (IOException e) {  e.printStackTrace();
	  }finally {  if(inputStreamReader != null){  try {  inputStreamReader.close();
	          } catch (IOException e) {  e.printStackTrace();
	          }
	      }
	      if(outputStreamWriter != null){  try {  outputStreamWriter.close();
	          } catch (IOException e) {  e.printStackTrace();
	          }
	      }
	  }
}

五、FileWriter和FileReader
eg:

public static void main(String[] args) {FileReader fileReader = null;
    FileWriter fileWriter = null;
    try {fileReader = new FileReader("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt");
        fileWriter = new FileWriter("C:\\Users\\Administrator\\Desktop\\test\\test02\\test01.txt");
        char[] chars = new char[1024];
        int length;
        while ((length = fileReader.read(chars)) != -1){fileWriter.write(chars,0,length);
        }
    } catch (IOException e) {e.printStackTrace();
    }finally {if(fileReader != null){try {fileReader.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
        if(fileWriter != null){try {fileWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

六、字符緩沖流

概述

（1）BufferedReader：字符緩存輸入流。從字符輸入流讀取文本，緩沖各個字符，從而實(shí)現(xiàn)字符、數(shù)組和行的高效讀取。
FileReader：內(nèi)部使用InputStreamReader，解碼過程，byte ->char，默認(rèn)緩存大小為8K。
BufferedReader：默認(rèn)緩存大小為8K，但可以手動指定緩存大小，把數(shù)據(jù)讀取到緩存中，減少每次轉(zhuǎn)換過程，效率更高。
（2）BufferedWriter：字符緩存輸出流。將文本寫入字符輸出流，緩存各個字符，從而提供單個字符、數(shù)組和字符串的高效寫入。
FileWriter：內(nèi)部使用InputStreamWriter，解碼過程，byte ->char，默認(rèn)緩存大小為8K。
BufferedWriter：默認(rèn)緩存大小為8K，但可以手動指定緩存大小，把數(shù)據(jù)讀取到緩存中，減少每次轉(zhuǎn)換過程，效率更高。
（3）字符緩沖流與字節(jié)緩沖流的思想一樣。

字符緩沖流的讀寫操作
eg：

public static void main(String[] args) {//寫數(shù)據(jù)
    BufferedWriter bufferedWriter = null;
    try {bufferedWriter = new BufferedWriter(new FileWriter("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"));
        bufferedWriter.write("好好學(xué)習(xí)，天天向上");
    } catch (IOException e) {e.printStackTrace();
    }finally {if(bufferedWriter != null){try {bufferedWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
    //讀數(shù)據(jù)
    BufferedReader bufferedReader = null;
    try {bufferedReader = new BufferedReader(new FileReader("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"));
        char[] chars = new char[1024];
        int length;
        while ((length = bufferedReader.read(chars)) != -1){System.out.println(new String(chars,0,length));
        }
    } catch (IOException e) {e.printStackTrace();
    }finally {if(bufferedReader != null){try {bufferedReader.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

字符緩沖流的換行操作

（1）BufferedWriter

方法	說明
void newLine()	寫一行分隔符，行分隔符字符串由系統(tǒng)屬性定義

（2）BufferedReader

方法	說明
String readLine()	讀一行文字。結(jié)果包含行的內(nèi)容的字符串，不包括任何行終止字符，如果流的結(jié)尾已經(jīng)到達(dá)，則返回null

eg：

public static void main(String[] args) {//寫數(shù)據(jù)
    BufferedWriter bufferedWriter = null;
    try {bufferedWriter = new BufferedWriter(new FileWriter("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"));
        for(int i=1; i<=10; i++){bufferedWriter.write("qizekj"+i);
            bufferedWriter.newLine();
        }
    } catch (IOException e) {e.printStackTrace();
    } finally {if (bufferedWriter != null) {try {bufferedWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
    //讀數(shù)據(jù)
    BufferedReader bufferedReader = null;
    try {bufferedReader = new BufferedReader(new FileReader("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"));
        String str;
        while ((str = bufferedReader.readLine()) != null) {System.out.println(str);
        }
    } catch (IOException e) {e.printStackTrace();
    } finally {if (bufferedReader != null) {try {bufferedReader.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }

    }
}

字符緩沖流復(fù)制文本文件

eg：

public static void main(String[] args) {BufferedReader bufferedReader = null;
    BufferedWriter bufferedWriter = null;
    try {bufferedReader = new BufferedReader(new FileReader("C:\\Users\\Administrator\\Desktop\\test\\test01\\test01.txt"));
        bufferedWriter = new BufferedWriter(new FileWriter("C:\\Users\\Administrator\\Desktop\\test\\test02\\test01.txt"));
        String str;
        while ((str = bufferedReader.readLine()) != null) {bufferedWriter.write(str);
            bufferedWriter.newLine();
        }
    } catch (IOException e) {e.printStackTrace();
    } finally {if (bufferedReader != null) {try {bufferedReader.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
        if (bufferedWriter != null) {try {bufferedWriter.close();
            } catch (IOException e) {e.printStackTrace();
            }
        }
    }
}

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