PrintWriter类

PrintWriter是一种过滤流，也是一种处理流，即能对字节流和字符流进行处理。

1.查询API后，我们发现，会有八种构造方法。即：

• PrintWriter(File file)

  Creates a new PrintWriter, without automatic line flushing, with the specified file.
  PrintWriter(File file, String csn)

  Creates a new PrintWriter, without automatic line flushing, with the specified file and charset.
  PrintWriter(OutputStream out)

  Creates a new PrintWriter, without automatic line flushing, from an existing OutputStream.
  PrintWriter(OutputStream out, boolean autoFlush)

  Creates a new PrintWriter from an existing OutputStream.
  PrintWriter(String fileName)

  Creates a new PrintWriter, without automatic line flushing, with the specified file name.
  PrintWriter(String fileName, String csn)

  Creates a new PrintWriter, without automatic line flushing, with the specified file name and charset.
  PrintWriter(Writer out)

  Creates a new PrintWriter, without automatic line flushing.
  PrintWriter(Writer out, boolean autoFlush)

  Creates a new PrintWriter.

2.实现了三种接口。

1) Closeable接口， 所以它有pw.close()方法来实现对PrintWriter的关闭。

2) Flushable接口，所以它有pw.flush()方法来实现人为的刷新。

3) Appendable接口，所以它有pw.append(char c)方法来向此输出流中追加指定字符，等价于print().

3.方法自寻查询api

4.举例：

 import java.io.IOException;
 import java.io.PrintWriter;
 import java.io.FileWriter;
 import java.io.File;

 public class PrintWriterDemo {

     public static void main(String[] args) {
         PrintWriter pw = null;
         String name = "张松伟";
         int age = ;
         float score = 32.5f;
         char sex = '男';
         try {
             pw = new PrintWriter(new FileWriter(new File("e:\\file.txt")), true);
             pw.printf("姓名：%s;年龄：%d;性别：%c;分数：%5.2f;", name, age, sex, score);
             pw.println();
             pw.println("多多指教");
             pw.write(name.toCharArray());
         } catch (IOException e) {
             e.printStackTrace();
         } finally {
             pw.close();
         }
     }
 }