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
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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"); } } ?
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