java IO流相关

野性酷女 2021-12-18 07:15 217阅读 0赞

#### 1.体系图解 ####

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQwODk2OTk3_size_16_color_FFFFFF_t_70]

#### 2.代码 ####

2.1 字符流读取文件

package com.fjh;
    
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.io.IOException;
    import java.io.Reader;
    
    public class CharStream { 
    
    	public static void main(String[] args) throws IOException { 
    		//System.getProperty("user.dir")读取用户当前工作环境目录
    		File file = new File(System.getProperty("user.dir")+"/1.txt");
    		if(!file.exists()){ 
    			try { 
    				file.createNewFile();
    			} catch (IOException e) { 
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		//字符流
    		Reader read = new FileReader(file);
    		//读内容
    		char[] cbuf = new char[1024];//每次读取的字符数
    		int len = 0;
    		String content = null;
    		//将字节数组转化为字符串
    		while((len = read.read(cbuf)) != -1){ //返回-1代表的是已经读取完毕
    			 content =new String(cbuf, 0, len);
    			
    		}
    		System.out.println("读取的内容为:"+content);
    		 if(null != read){ 
    			 read.close();
    		 }
    	}
    
    }
    
    package com.fjh;
    
    import java.io.BufferedReader;
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.io.IOException;
    import java.io.Reader;
    
    public class BufferReaderStream { 
    
    	public static void main(String[] args) throws IOException { 
    		File file = new File(System.getProperty("user.dir") + "/1.txt");
    		if (!file.exists()) { 
    			try { 
    				file.createNewFile();
    			} catch (IOException e) { 
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		Reader read = new FileReader(file);
    		
    		BufferedReader bf = new BufferedReader(read);
    		String str = null;
    		while ((str = bf.readLine()) != null){ 
    			System.out.println(str);
    		}
    		bf.close();
    
    	}
    
    }

2.2 字节流读取文件，字符流写入文件

package com.fjh;
    
    import java.io.File;
    import java.io.FileInputStream;
    import java.io.FileOutputStream;
    import java.io.FileWriter;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.OutputStream;
    import java.io.Writer;
    
    public class ByteStream { 
    	public static void main(String[] args) throws IOException { 
    		File file = new File(System.getProperty("user.dir") + "/1.txt");
    		if (!file.exists()) { 
    			try { 
    				file.createNewFile();
    			} catch (IOException e) { 
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    		// 字节流
    		InputStream is = new FileInputStream(file);
    		// 读内容,按字节读取
    		byte[] b = new byte[1024];// 每次读取的字节数
    		int len = 0;
    		String content = null;
    		// 将字节数组转化为字符串
    		while ((len = is.read(b)) != -1) { // 返回-1代表的是已经读取完毕
    			content = new String(b, 0, len);
    
    		}
    		System.out.println("读取的内容为:" + content);
    		if (null != is) { 
    			is.close();
    		}
    
    		// 字节流写入文件
    		File file2 = new File(System.getProperty("user.dir") + "/2.txt");
    		if (!file2.exists()) { 
    			try { 
    				file2.createNewFile();
    			} catch (IOException e) { 
    				// TODO Auto-generated catch block
    				e.printStackTrace();
    			}
    		}
    
    		OutputStream os = new FileOutputStream(file2);
    		String str = "fsdf看发生";
    		os.write(str.getBytes());
    		os.close();
    		// 字符流写入内容
    		Writer write = new FileWriter(file2, true);// true表示从文件后面接着写入
    
    		String str2 = "发生纠纷好看fsdaf";
    
    		write.write(str2);
    
    		// 关闭
    		write.close();
    	}
    
    }

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