Java字节流--输出流OutputStream和输入流InputStream

旧城等待， 2022-05-20 07:50 184阅读 0赞

**OutputStream和InputStream都是抽象类**

OutputStream定义和InputStream定义

<table> 
 <tbody> 
 <tr> 
 <td><span style="text-align:justify;color:rgb(79,79,79);text-transform:none;text-indent:0px;letter-spacing:normal;font-size:16px;font-style:normal;font-variant:normal;text-decoration:none;word-spacing:0px;background-color:transparent;">OutputStream</td> 
 <td>InputStream</td> 
 </tr> 
 <tr> 
 <td><span style="background-color:transparent;color:rgb(53,56,51);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;">public abstract class <span style="background-color:transparent;color:rgb(53,56,51);font-size:14px;font-style:normal;font-variant:normal;font-weight:700;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;">OutputStream<span style="background-color:transparent;color:rgb(53,56,51);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;"> extends <a title="class in java.lang" style="background-color:transparent;color:rgb(74,103,130);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;" rel="nofollow">Object</a><span style="background-color:transparent;color:rgb(53,56,51);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;"> implements <a title="interface in java.io" style="background-color:transparent;color:rgb(74,103,130);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;" rel="nofollow">Closeable</a><span style="background-color:transparent;color:rgb(53,56,51);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;">, <a title="interface in java.io" style="background-color:transparent;color:rgb(74,103,130);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;" rel="nofollow">Flushable</a></td> 
 <td><span style="background-color:transparent;color:rgb(53,56,51);font-family:'DejaVu Sans Mono', monospace;font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;"><span style="background-color:transparent;color:rgb(53,56,51);font-family:'DejaVu Sans Mono', monospace;font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;">public abstract class <span style="background-color:transparent;color:rgb(53,56,51);font-size:14px;font-style:normal;font-variant:normal;font-weight:700;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;">InputStream<span style="background-color:transparent;color:rgb(53,56,51);font-family:'DejaVu Sans Mono', monospace;font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;"> extends <a title="class in java.lang" style="background-color:transparent;color:rgb(74,103,130);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;" rel="nofollow">Object</a><span style="background-color:transparent;color:rgb(53,56,51);font-family:'DejaVu Sans Mono', monospace;font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;"> implements <a title="interface in java.io" style="background-color:transparent;color:rgb(74,103,130);font-size:14px;font-style:normal;font-variant:normal;font-weight:400;letter-spacing:normal;text-align:left;text-decoration:none;text-indent:0px;text-transform:none;word-spacing:0px;" rel="nofollow">Closeable</a></td> 
 </tr> 
 </tbody> 
</table>

常用的两个实现子类

FileOutputStream

package demo;
    
    import java.io.File;
    import java.io.FileOutputStream;
    import java.io.OutputStream;
    /**
     * 输入输出是相对内存而言。
     * 输出：从内存往硬盘写东西。对内存来说是输出，对硬盘来说是写入（write）
     *  输入：从硬盘往内存写东西。对内存来说是输入，对硬盘来说是写入（read）
     * @author Administrator
     *
     */
    public class TestDemo
    {
    	public static void main(String[] args) throws Exception
    	{
    		//1、定义要输出文件的路径
    		File file = new File("g:"+File.separator+"demo"+File.separator+"test.txt");
    		if(!file.getParentFile().exists())//判断父路径是否存在
    		{
    			file.getParentFile().mkdirs();//不存在就创建
    		}
    		//2、应该使用OutputStream和其子类进行对象的实例化，此时目录存在，文件还不存在
    		//文件不存在会自动创建
    		OutputStream output = new FileOutputStream(file);//覆盖原来内容
    //		OutputStream output = new FileOutputStream(file,true);//对原来内容追加
    
    		//3、要进行文件内容的输出
    		String str = "好好学习天天向上！";
    		byte[] data = str.getBytes();
    		output.write(data);//全部字节输出
    //		output.write(data,0,3);//部分输出
    		
    		//4、资源使用完要关闭
    		output.close();
    	}
    }

FileInputStream

package demo;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.InputStream;
    
    public class TestDemo2
    {
    	public static void main(String[] args) throws Exception
    	{
    		//1、定义要输入文件的路径
    		File file = new File("g:"+File.separator+"demo"+File.separator+"test.txt");
    		if (!file.exists())//文件不存在就不操作了
    		{
    			System.out.println("文件不存在");
    		}
    		else {
    			//2、找一根传输的管子
    			InputStream is = new FileInputStream(file);
    			//3、存放传输的数据
    			byte[] data = new byte[1024];
    			int temp = 0 ;
    			int foot = 0 ;
    			while((temp=is.read())!=-1)
    			{
    				data[foot++] = (byte) temp ;
    			}
    			System.out.println("【"+new String(data,0,foot)+"】");
    			//4、关闭
    			is.close();
    			
    		}
    	}
    }

结果：

【好好学习天天向上！】

**FileOutputStream**和**FileInputStream**

<table> 
 <tbody> 
 <tr> 
 <td>&nbsp;</td> 
 <td>FileOutputStream</td> 
 <td>FileInputStream</td> 
 </tr> 
 <tr> 
 <td>定义</td> 
 <td>public class FileInputStream extends InputStream</td> 
 <td>public class FileInputStream extends InputStream</td> 
 </tr> 
 <tr> 
 <td>构造方法</td> 
 <td><img alt="" src="https://img-blog.csdn.net/20180715121827217?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMyOTY1MTg3/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70"> </td> 
 <td><img alt="" src="https://img-blog.csdn.net/20180715121835714?watermark/2/text/aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMyOTY1MTg3/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70"> </td> 
 </tr> 
 <tr> 
 <td>常用方法</td> 
 <td>void close()&nbsp; void write(byte[] b)&nbsp; void write(byte[] b, int off, int len)&nbsp; void write(int b)&nbsp; </td> 
 <td>void close() int read()&nbsp; int read(byte[] b)&nbsp; int read(byte[] b, int off, int len)&nbsp; </td> 
 </tr> 
 </tbody> 
</table>