java常用类解析三：IO系统装饰类

java IO系统采用装饰器模式，用一些装饰类来装饰输入输出来，提供更强大的IO操作

FilterInputStream(FilterOutputStream)继承自InputStream(Outputstream)

 常用装饰类(都继承自FilterInputStream)               功能

DataInputStream(DataOutputStream)                 读写基本类型即UTF

BufferedInputStream(BufferedOutputStream)      使用缓冲区

PrintStream继承自Outputstream，用于格式化输出到文本或控制台等

 

示例：

import java.io.BufferedInputStream;  
import java.io.BufferedOutputStream;  
import java.io.DataInputStream;  
import java.io.DataOutputStream;  
import java.io.FileInputStream;  
import java.io.FileNotFoundException;  
import java.io.FileOutputStream;  
import java.io.IOException;  
  
/* 
 * DataInputStream继承自FilterInputStream(FilterInputStream继承自InputStream) 
 * 用来装饰InputStream，提供可移植方式从流读取基本数据类型 
 * DataOutputStream继承自FilterOutputStream(FilterOutputStream继承自OutputStream) 
 * 用来装饰OutputStream，提供可移植方式向流写入基本数据类型 
 * DataInputStream/DataOutputStream可以实现数据的存储与恢复 
 */  
public class DataInputStreamDemo {  
    public static void main(String[] args) {  
        DataOutputStream dataOutStream = null;  
        try {  
            dataOutStream = new DataOutputStream(new BufferedOutputStream(  
                    new FileOutputStream("file/aa.data")));  
        } catch (FileNotFoundException e) {  
            // TODO Auto-generated catch block   
            e.printStackTrace();  
        }  
        try {// 写入文件   
            dataOutStream.writeChar('a');  
            dataOutStream.writeInt(3);  
            dataOutStream.writeDouble(5.5);  
            dataOutStream.writeFloat(3.2f);  
            dataOutStream.writeUTF("nihaoma");  
            dataOutStream.close();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
          
        DataInputStream dataInputStream = null;  
        try {  
            dataInputStream = new DataInputStream(new BufferedInputStream(  
                    new FileInputStream("file/aa.data")));  
        } catch (FileNotFoundException e) {  
            e.printStackTrace();  
        }  
        try {// 读取文件   
            System.out.println(dataInputStream.readChar());  
            System.out.println(dataInputStream.readInt());  
            System.out.println(dataInputStream.readDouble());  
            System.out.println(dataInputStream.readFloat());  
            System.out.println(dataInputStream.readUTF());  
            dataInputStream.close();  
        } catch (IOException e) {  
            e.printStackTrace();  
        }  
    }  
}  

 

import java.io.FileNotFoundException;  
import java.io.PrintStream;  
  
/* 
 * 继承自FilterOutputStream，其中DataOutputStream处理数据的存储，PrintStream处理显示 
 * 用于格式化打印 
 */  
public class PrintStreamDemo {  
    public static void main(String[] args) throws FileNotFoundException {  
        // 把数据可视化格式显示到文本文件中   
        PrintStream printStream = new PrintStream("file/test2.txt");  
        printStream.println('a');  
        printStream.println(2);  
        printStream.println(3.2);  
        printStream.println("liuhaifang");  
        printStream.println("刘海房");  
        // 可视化显示到控制台   
        printStream = new PrintStream(System.out);  
        printStream.println("hello  java");  
    }  
}