java读写文件

悠悠 2022-06-09 01:25 279阅读 0赞

java读写文件

java io是我们编程开发之中经常用到的工具之一，java读写文件更是家常便饭，下面分享一下java读写文件的工具类，有需要童鞋复制粘贴即可使用。

一、java读文件

/**
    	 * 一个一个读，效率不高
    	 * @param file    文件路径
    	 * @throws IOException
    	 */
    	public static void readSimple(File file) throws IOException{
    		int temp = 0;
    		String str = "";
    		BufferedReader bf = new BufferedReader(new FileReader(file));
    		while((temp=bf.read())!=-1){
    			str += (char)temp;
    		}
    		System.out.println("结果是：" + new String(str));
    	}
    
    	/**
    	 * 一次性读完
    	 * @param file    文件路径
    	 * @throws IOException
    	 */
    	public static void readAll(File file) throws IOException{
    		FileInputStream fis = new FileInputStream(file);
    		int size = fis.available();//求出长度一次性读完
    		byte[] by = new byte[size];
    		fis.read(by);
    		fis.close();
    		System.out.println("输出结果是:" + new String(by,"GB2312"));
    	}

二、java写文件

/**
    	 * A方法追加文件：使用RandomAccessFile
             * 样例调用:WriteInfoToFile.appendMethodA("E:/huawei/test.txt", 
             *          new String(new StringBuffer().toString().getBytes(Charset.forName("GBK"))));
            * @return 
    	 */
    	public static synchronized void appendMethodA(String fileName, String arm) {
    		try {
    			// 打开一个随机访问文件流，按读写方式
    			RandomAccessFile randomFile = new RandomAccessFile(fileName, "rw");
    			// 文件长度，字节数
    			long fileLength = randomFile.length();
    			//将写文件指针移到文件尾。
    			randomFile.seek(fileLength);
    			randomFile.writeBytes(arm);
    			randomFile.close();
    		} catch (IOException e) {
    			LOGGER.error(e.getMessage(), e);
    		}
    	}
    
    	/**
    	 * B方法追加文件：使用FileWriter
    	 * yyyy_MM_dd_HH_mm
    	 * dateformat!= null && dateformat.contains("yyy_MM_dd")
             *调用样例:  WriteInfoToFile.appendMethodB(filePath, new StringBuffer().append(String a).toString(), 
             *            fileName);
            */
    	public static synchronized void appendMethodB(String filepath, String context, String fileName) {
    		Writer writer = null;
    		String tmpFileName = filepath+emsName+".tmp";
    		String txtFileName = filepath+emsName+".txt";
    		File file = new File(tmpFileName);
    		try {
    			if (!file.exists()) {
    				file = new File(tmpFileName.substring(0, filepath.lastIndexOf("/")));
    				file.mkdirs();
    				file = new File(tmpFileName);
    				file.createNewFile();
    			}
    			//打开一个写文件器，构造函数中的第二个参数true表示以追加形式写文件
    			writer = new OutputStreamWriter(new FileOutputStream(file, true), "UTF-8");
    			writer.write(context);
    		} catch (IOException e) {
    			LOGGER.error(e.getMessage(), e);
    		} finally{
    			if(writer != null){
    				try {
    					writer.close();
    				} catch (IOException e) {
    					LOGGER.error(e.getMessage(), e);
    				}
    			}
    		}
    		File txtFile = new File(txtFileName);
    		boolean reName = file.renameTo(txtFile);
    		LOGGER.info("生成文件成功，更名txt文件：{}", reName);
    	}
    	
    	public static synchronized void appendMethodC(String filepath, String context,String name) {
    		
    		String time = new SimpleDateFormat("yyyy-MM-dd").format(new Date());
    		String filename = filepath + name + time+".txt";
    		File file = new File(filename);
    		try {
    			if (!file.exists()) {
    				file = new File(filename.substring(0, filepath.lastIndexOf("/")));
    				file.mkdirs();
    				file = new File(filename);
    				file.createNewFile();
    			}
    			
    			FileWriter writer = new FileWriter(filename, true);
    			writer.write(context);
    			writer.close();
    		} catch (IOException e) {
    			LOGGER.error(e.getMessage(), e);
    		}
    		
    	}