java常用類解析三：IO系統裝飾類

java IO系統採用裝飾器模式，用一些裝飾類來裝飾輸入輸出來，提供更強大的IO操作

FilterInputStream(FilterOutputStream)繼承自InputStream(Outputstream)

常用裝飾類(都繼承自FilterInputStream)               功能

DataInputStream(DataOutputStream)                 讀寫基本類型即UTF

BufferedInputStream(BufferedOutputStream)      使用緩衝區

PrintStream繼承自Outputstream，用于格式化輸出到文本或控制台等

 

樣本：

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繼承自FilterInputStream(FilterInputStream繼承自InputStream) * 用來裝飾InputStream，提供可移植方式從流讀取基礎資料型別 (Elementary Data Type) * DataOutputStream繼承自FilterOutputStream(FilterOutputStream繼承自OutputStream) * 用來裝飾OutputStream，提供可移植方式向流寫入基礎資料型別 (Elementary Data Type) * DataInputStream/DataOutputStream可以實現資料的儲存與恢複 */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 {// 寫入檔案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 {// 讀取檔案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;/* * 繼承自FilterOutputStream，其中DataOutputStream處理資料的儲存，PrintStream處理顯示 * 用于格式化列印 */public class PrintStreamDemo {public static void main(String[] args) throws FileNotFoundException {// 把資料視覺效果格式顯示到文字檔中PrintStream printStream = new PrintStream("file/test2.txt");printStream.println('a');printStream.println(2);printStream.println(3.2);printStream.println("liuhaifang");printStream.println("劉海房");// 可視化顯示到控制台printStream = new PrintStream(System.out);printStream.println("hello  java");}}