Java進階核心之OutputStream流-有解無憂

Java進階核心之OutputStream流

OutputStream是輸出位元組流的父類，它是一個抽象類

	void write(int b)
	講解：將指定的位元組寫入輸出流
	
	void write(byte[] b)throws IOException
	講解：將b.length個位元組的byte陣列寫入當前輸出流
	
	void flush() throws IOException
	講解： write是寫到緩沖區中，可以認為是記憶體中,當緩沖區滿時系統會?自動將緩沖區的內容寫入檔案，但是一般還有一部分有可能會留在記憶體這個緩沖區中, 所以需要呼叫flush慷訓沖區資料，
	
	void close() throws IOException
	講解：關閉輸入流并釋放與該流關聯的系統資源

常見子類
- FileOutputStream
  - 抽象類OutputStream用來具體實作類的創建物件, 檔案位元組輸出流, 對檔案資料以位元組的形式進行行輸出的操作
  - 建構式

	//傳入輸出的檔案地址
	public FileOutputStream(String name)
	
	//傳入目標輸出的檔案物件
	public FileOutputStream(File file)
	
	//傳入目標輸出的檔案物件, 是否可以追加內容
	public FileOutputStream(File file, boolean append)

eg：

package domee.chapter10_3;

import domee.chapter6_6.Vehicle;

import java.io.*;

public class Main {
    public static void main(String[] args) throws IOException {
        String dir = "C:\\Users\\123\\Desktop\\test";
        String name = "a.txt";
        String name0 = "b.txt";
        File file = new File(dir,name);
        InputStream inputStream = new FileInputStream(file);
//        printlnFile(inputStream);
//        System.out.println("==================");
        OutputStream outputStream = new FileOutputStream(dir+File.separator+name0);
        //testWrite(inputStream,outputStream);
        testWriteBuf(inputStream,outputStream);

    }

    public static void read(InputStream inputStream)throws IOException{
        int readrulst =  inputStream.read();
        System.out.println(readrulst);
    }

    public static void printlnFile(InputStream inputStream)throws IOException{
        byte[] buf = new byte[inputStream.available()];
        int lenget;
        while ((lenget = inputStream.read(buf)) != -1){
            System.out.print(new String(buf,0,lenget));
        }
        inputStream.close();


    }
    //單個位元組讀取性能差效果不好，中文會有亂碼
    public static void testWrite(InputStream inputStream,OutputStream outputStream)throws IOException{
        int value = 0;
        while (value != -1){
            value = inputStream.read();
            //System.out.print(value);
            outputStream.write(value);
        }
        inputStream.close();
        outputStream.close();
    }

    public static void testWriteBuf(InputStream inputStream,OutputStream outputStream)throws IOException{
        byte[] buf = new byte[1024];
        int length;
        while ((length = inputStream.read(buf)) != -1){
            outputStream.write(buf,0,length);
        }
        inputStream.close();
        outputStream.close();
    }

}

在這里插入圖片描述

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標籤：java

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