文件读写--ObjectStreamDemo1

package test;import java.io.Serializable;public class User implements Serializable {private static final long serialVersionUID = 1L;private String name;private int number;public User() {}public User(String name, int number) {this.name = name;this.number = number;}public void setName(String name) {this.name = name;}public void setNumber(int number) {this.number = number;}public String getName() {return name;}public int getNumber() {return number;}} 

=======================================================

package test;import java.io.*;import java.util.*;public class ObjectStreamDemo1 {public static void main(String[] args) {User[] users = { new User("cater", 101), new User("justin", 102) };// 写入新文件writeObjectsToFile(users, "D://FileStreamDemo1.txt");try {// 读取文件数据users = readObjectsFromFile("D://FileStreamDemo1.txt");// 显示读回的对象for (User user : users) {System.out.printf("%s/t%d%n", user.getName(), user.getNumber());}System.out.println();users = new User[2];users[0] = new User("momor", 103);users[1] = new User("becky", 104);// 附加新对象至文件appendObjectsToFile(users, "D://FileStreamDemo1.txt");// 读取文件数据users = readObjectsFromFile("D://FileStreamDemo1.txt");// 显示读回的对象for (User user : users) {System.out.printf("%s/t%d%n", user.getName(), user.getNumber());}}catch (ArrayIndexOutOfBoundsException e) {System.out.println("没有指定文件名!");}catch (FileNotFoundException e) {e.printStackTrace();}}// 将指定的对象写入至指定的文件public static void writeObjectsToFile(Object[] objs, String filename) {File file = new File(filename);try {ObjectOutputStream objOutputStream =new ObjectOutputStream(new FileOutputStream(file));for (Object obj : objs) {// 将对象写入文件objOutputStream.writeObject(obj);}// 关闭流objOutputStream.close();}catch (IOException e) {e.printStackTrace();}}// 将指定文件中的对象数据读回public static User[] readObjectsFromFile(String filename) throws FileNotFoundException {File file = new File(filename);// 如果文件不存在就丢出异常if (!file.exists()){throw new FileNotFoundException();}// 使用List先存储读回的对象List<User> list = new ArrayList<User>();try {FileInputStream fileInputStream = new FileInputStream(file);ObjectInputStream objInputStream = new ObjectInputStream(fileInputStream);while (fileInputStream.available() > 0) {list.add((User)objInputStream.readObject());}objInputStream.close();} catch (ClassNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}User[] users = new User[list.size()];return list.toArray(users);}// 将对象附加至指定的文件之后public static void appendObjectsToFile(Object[] objs, String filename)throws FileNotFoundException {File file = new File(filename);// 如果文件不存在则丢出异常if (!file.exists())throw new FileNotFoundException();try {// 附加模式ObjectOutputStream objOutputStream = new ObjectOutputStream(new FileOutputStream(file, true)) {// 如果要附加对象至文件后// 必须重新定义这个方法protected void writeStreamHeader() throws IOException {}};for (Object obj : objs) {// 将对象写入文件objOutputStream.writeObject(obj);}objOutputStream.close();} catch (IOException e) {e.printStackTrace();}}}

 

打印输出：

cater    101
justin    102

cater    101
justin    102
momor    103
becky    104