Java语言中常用的io类

Java语言中常用的io类(处理流)
1. BufferedInputStream 和 BufferedOuputStream
2. TransformInputStream 和 TransformOutputStream
3. DataInputStream 和 DataOutputStream
4. ByteArrayInputStream 和 ByteArrayOutputStream
5. PrintStream 和 PrintWriter
6. ObjectInputStream 和 ObjectOutputStream


先来个ObjectIO实例，其他以后再补
1. ObjectInputStream和ObjectOutputStream
主要是对对象的写入与读取操作，也可用于网络的数据传输
实例:

package com.zkl.objectio;

import java.io.Serializable;

/**
 * 创建一个学生类,并标记为序列化(实现Serializable接口)
 * 该学生有:名字name
 * 			编号id
 * @author zkl1
 *
 */
public class Student implements Serializable {
	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;
	private String name=null;

	//如果使用了transient关键字，则不会写入
	//private transient String name=null;

	private long id=0;
	public Student(){}
	public Student(String name,long id){
		this.name=name;
		this.id=id;
	}
	public void setName(String name){
		this.name=name;
	}
	public String getName(){
		return this.name;
	}
	public void setId(long id){
		this.id=id;
	}
	public long getId(){
		return this.id;
	}
	public void showData(){
		System.out.println(this.name);
		System.out.println(this.id);
	}
}

package com.zkl.objectio;
/**
 * 通过ObjectOutputStream存储的对象必须是可以序列化的
 * 而对象必须实现Serializable接口，以标记该对象是可以序列化的。
 * Serializable接口没有实现的方法,只是作为序列化标记。
 * @author zkl1
 *
 */
import java.io.*;
import java.util.*;
public class ObjectIOTest {

	/**
	 * 数据对象写入文件
	 * @param objs
	 * @param filename
	 */
	public void writeObjectToFile(Object[] objs,File filename){
		File file = filename;
		try {
			ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file));
			for(Object obj:objs){
				oos.writeObject(obj);
			}
			oos.close();
		} catch (Exception e) {
			// TODO: handle exception
			System.out.println(e.getMessage());
		}
	}
	
	/**
	 * 从文件中读取数据对象
	 * @param filename
	 * @return
	 * @throws FileNotFoundException
	 */
	public Object[] readObjectFromFile(File filename) throws FileNotFoundException{
		File file = filename;
		if(!file.exists()){
			throw new FileNotFoundException();
		}
		//定义一个只存储Student对象的泛型List容器
		//List<Student> list = new ArrayList<Student>();
		List list = new ArrayList();
		try {
			FileInputStream fis = new FileInputStream(file);
			ObjectInputStream ois = new ObjectInputStream(fis);
			while(fis.available()>0){
				//list.add((Student)ois.readObject());
				list.add(ois.readObject());
			}
			fis.close();
			ois.close();
		} catch (Exception e) {
			// TODO: handle exception
		}
		
		return list.toArray();
	}
	
	/**
	 * 将数据对象添加到文件的未尾
	 * @param objs
	 * @param filename
	 * @throws FileNotFoundException
	 */
	public void appendObjectToFile(Object[] objs,File filename) throws FileNotFoundException{
		File file = filename;
		//如果文件不存在，则抛出异常
		if(!file.exists()){
			throw new FileNotFoundException();
		}
		try {
			//不写入标示头，重写writeStreamHeader()函数
			ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file,true))
			{
				protected void writeStreamHeader(){}
			};
			for(Object obj:objs){
				oos.writeObject(obj);
			}
			oos.close();
		} catch (Exception e) {
			// TODO: handle exception
			System.out.println(e.getMessage());
		}
	}
	
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		File file = new File("c:\\data.dat");
		ObjectIOTest oit = new ObjectIOTest();
		Object stu[] = {new Student("zkl",12345),
						 new Student("中国星",5677),
						 new Student("china34420",8201868)};
		oit.writeObjectToFile(stu, file);
		
		try {
			Object objs[] = oit.readObjectFromFile(file);
			Student st;
			for(int i=0;i<objs.length;i++){
				if(objs[i] instanceof Student){
					st = (Student)objs[i];
					st.showData();
				}
			}
			
			Object st2[] = {new Student("dd",33),new Student("eeee",444) };
			oit.appendObjectToFile(st2, file);
			
			System.out.println();
			
			objs = oit.readObjectFromFile(file);
			for(Object obj:objs){
				((Student)obj).showData();
			}
		} catch (FileNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}

}