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：

package test;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 blocke.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();}}}

package test;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");}}

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