corejava第9版

corejava第9版/v2ch01/textFile/TextFileTest.java

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+package textFile;
+
+import java.io.*;
+import java.util.*;
+
+/**
+ * @version 1.13 2012-05-30
+ * @author Cay Horstmann
+ */
+public class TextFileTest
+{
+   public static void main(String[] args) throws IOException
+   {
+      Employee[] staff = new Employee[3];
+
+      staff[0] = new Employee("Carl Cracker", 75000, 1987, 12, 15);
+      staff[1] = new Employee("Harry Hacker", 50000, 1989, 10, 1);
+      staff[2] = new Employee("Tony Tester", 40000, 1990, 3, 15);
+
+      // save all employee records to the file employee.dat
+      try (PrintWriter out = new PrintWriter("employee.dat", "UTF-8"))
+      {         
+         writeData(staff, out);
+      }
+      
+      // retrieve all records into a new array
+      try (Scanner in = new Scanner(
+            new FileInputStream("employee.dat"), "UTF-8"))
+      {
+         Employee[] newStaff = readData(in);
+
+         // print the newly read employee records
+         for (Employee e : newStaff)
+            System.out.println(e);
+      }
+   }
+
+   /**
+    * Writes all employees in an array to a print writer
+    * @param employees an array of employees
+    * @param out a print writer
+    */
+   private static void writeData(Employee[] employees, PrintWriter out) throws IOException
+   {
+      // write number of employees
+      out.println(employees.length);
+
+      for (Employee e : employees)
+         writeEmployee(out, e);
+   }
+
+   /**
+    * Reads an array of employees from a scanner
+    * @param in the scanner
+    * @return the array of employees
+    */
+   private static Employee[] readData(Scanner in)
+   {
+      // retrieve the array size
+      int n = in.nextInt();
+      in.nextLine(); // consume newline
+
+      Employee[] employees = new Employee[n];
+      for (int i = 0; i < n; i++)
+      {
+         employees[i] = readEmployee(in);
+      }
+      return employees;
+   }
+   
+   /**
+    * Writes employee data to a print writer
+    * @param out the print writer
+    */
+   public static void writeEmployee(PrintWriter out, Employee e)
+   {
+      GregorianCalendar calendar = new GregorianCalendar();
+      calendar.setTime(e.getHireDay());
+      out.println(e.getName() + "|" + e.getSalary() + "|" + calendar.get(Calendar.YEAR) + "|"
+            + (calendar.get(Calendar.MONTH) + 1) + "|" + calendar.get(Calendar.DAY_OF_MONTH));
+   }
+
+   /**
+    * Reads employee data from a buffered reader
+    * @param in the scanner
+    */
+   public static Employee readEmployee(Scanner in)
+   {
+      String line = in.nextLine();
+      String[] tokens = line.split("\\|");
+      String name = tokens[0];
+      double salary = Double.parseDouble(tokens[1]);
+      int year = Integer.parseInt(tokens[2]);
+      int month = Integer.parseInt(tokens[3]);
+      int day = Integer.parseInt(tokens[4]);
+      return new Employee(name, salary, year, month, day);
+   }   
+}