Java的字符读写类CharArrayReader和CharArrayWriter使用示例


CharArrayReader
CharArrayReader 是字符数组输入流。它和ByteArrayInputStream类似,只不过ByteArrayInputStream是字节数组输入流,而CharArray是字符数组输入流。CharArrayReader 是用于读取字符数组,它继承于Reader。操作的数据是以字符为单位!
CharArrayReader 函数列表:

CharArrayReader(char[] buf)
CharArrayReader(char[] buf, int offset, int length)

void   close()
void   mark(int readLimit)
boolean  markSupported()
int    read()
int    read(char[] buffer, int offset, int len)
boolean  ready()
void   reset()
long   skip(long charCount)

示例代码:
关于CharArrayReader中API的详细用法,参考示例代码(CharArrayReaderTest.java):

import java.io.CharArrayReader;
import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayReaderTest {

  private static final int LEN = 5;
  // 对应英文字母“abcdefghijklmnopqrstuvwxyz”
  private static final char[] ArrayLetters = 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) {
    tesCharArrayReader() ;
  }

  /**
   * CharArrayReader的API测试函数
   */
  private static void tesCharArrayReader() {
    try {
      // 创建CharArrayReader字符流,内容是ArrayLetters数组
      CharArrayReader car = new CharArrayReader(ArrayLetters);

      // 从字符数组流中读取5个字符
      for (int i=0; i<LEN; i++) {
        // 若能继续读取下一个字符,则读取下一个字符
        if (car.ready() == true) {
          // 读取“字符流的下一个字符”
          char tmp = (char)car.read();
          System.out.printf("%d : %c\n", i, tmp);
        }
      }

      // 若“该字符流”不支持标记功能,则直接退出
      if (!car.markSupported()) {
        System.out.println("make not supported!");
        return ;
      }

      // 标记“字符流中下一个被读取的位置”。即--标记“f”,因为因为前面已经读取了5个字符,所以下一个被读取的位置是第6个字符”
      // (01), CharArrayReader类的mark(0)函数中的“参数0”是没有实际意义的。
      // (02), mark()与reset()是配套的,reset()会将“字符流中下一个被读取的位置”重置为“mark()中所保存的位置”
      car.mark(0);

      // 跳过5个字符。跳过5个字符后,字符流中下一个被读取的值应该是“k”。
      car.skip(5);

      // 从字符流中读取5个数据。即读取“klmno”
      char[] buf = new char[LEN];
      car.read(buf, 0, LEN);
      System.out.printf("buf=%s\n", String.valueOf(buf));

      // 重置“字符流”:即,将“字符流中下一个被读取的位置”重置到“mark()所标记的位置”,即f。
      car.reset();
      // 从“重置后的字符流”中读取5个字符到buf中。即读取“fghij”
      car.read(buf, 0, LEN);
      System.out.printf("buf=%s\n", String.valueOf(buf));
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

运行结果:

0 : a
1 : b
2 : c
3 : d
4 : e
buf=klmno
buf=fghij

CharArrayWriter
CharArrayReader 用于写入数据符,它继承于Writer。操作的数据是以字符为单位!
CharArrayWriter 函数列表

CharArrayWriter()
CharArrayWriter(int initialSize)

CharArrayWriter   append(CharSequence csq, int start, int end)
CharArrayWriter   append(char c)
CharArrayWriter   append(CharSequence csq)
void   close()
void   flush()
void   reset()
int   size()
char[]   toCharArray()
String   toString()
void   write(char[] buffer, int offset, int len)
void   write(int oneChar)
void   write(String str, int offset, int count)
void   writeTo(Writer out)

示例代码:
关于CharArrayWriter中API的详细用法,参考示例代码(CharArrayWriterTest.java):

import java.io.CharArrayReader;
import java.io.CharArrayWriter;
import java.io.IOException;

public class CharArrayWriterTest {

  private static final int LEN = 5;
  // 对应英文字母“abcdefghijklmnopqrstuvwxyz”
  private static final char[] ArrayLetters = 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) {

    tesCharArrayWriter() ;
  }

  /**
   * CharArrayWriter的API测试函数
   */
  private static void tesCharArrayWriter() {
    try {
      // 创建CharArrayWriter字符流
      CharArrayWriter caw = new CharArrayWriter();

      // 写入“A”个字符
      caw.write('A');
      // 写入字符串“BC”个字符
      caw.write("BC");
      //System.out.printf("caw=%s\n", caw);
      // 将ArrayLetters数组中从“3”开始的后5个字符(defgh)写入到caw中。
      caw.write(ArrayLetters, 3, 5);
      //System.out.printf("caw=%s\n", caw);

      // (01) 写入字符0
      // (02) 然后接着写入“123456789”
      // (03) 再接着写入ArrayLetters中第8-12个字符(ijkl)
      caw.append('0').append("123456789").append(String.valueOf(ArrayLetters), 8, 12);

      System.out.printf("caw=%s\n", caw);

      // 计算长度
      int size = caw.size();
      System.out.printf("size=%s\n", size);

      // 转换成byte[]数组
      char[] buf = caw.toCharArray();
      System.out.printf("buf=%s\n", String.valueOf(buf));

      // 将caw写入到另一个输出流中
      CharArrayWriter caw2 = new CharArrayWriter();
      caw.writeTo(caw2);
      System.out.printf("caw2=%s\n", caw2);
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

运行结果:

caw=ABCdefgh0123456789ijkl
size=22
buf=ABCdefgh0123456789ijkl
caw2=ABCdefgh0123456789ijkl


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