文件写入时使用缓冲区与不使用缓冲区效率提升3倍测试

//不使用缓冲区，用时100MS
    public static void main(String[] args) {
        Writer writer = null;
        try {
            Long startTime = System.currentTimeMillis();
            writer = new FileWriter("D:\\zp_project\\rt.txt");
            for (int i = 0; i <500000 ; i++) {
                writer.write(i);
            }
            Long endTime = System.currentTimeMillis();
            System.out.println(endTime-startTime);
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                writer.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }


//使用缓冲区 用时33MS
    public static void main(String[] args) {
        Writer writer = null;
        BufferedWriter bufferedWriter = null;

        try {
            Long start = System.currentTimeMillis();
            writer = new FileWriter("D:\\zp_project\\bf.txt");
            bufferedWriter = new BufferedWriter(writer);
            for (int i = 0; i <500000 ; i++) {
                bufferedWriter.write(i);
            }
            Long end = System.currentTimeMillis();
            System.out.println(end - start);
        } catch (IOException e) {
            e.printStackTrace();
        }finally {
            try {
                bufferedWriter.close();
                writer.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

    }

 转换流的使用示例

public static void main(String[] args) {
        String filePath = "D://bing/ge/hello.txt";
        try {
            //当文件编码格式是GBK时,要用转换流，可以从字节点转化为字符流
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(new FileInputStream(filePath),"gbk"));
            String redLine = "";
            Integer i = 1;
            while ((redLine = bufferedReader.readLine()) != null){
                System.out.println("第"+i+"行:"+redLine);
                i++;
            }
            bufferedReader.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

 3。创建文件与写入内容

public static void fileExist(String[] args) {
        String dirPath = "D://bing/ge";
        String filePath = dirPath+"/hello.txt";
        File file = new File(dirPath);
        if(!file.exists()){
            file.mkdirs();
            System.out.println("文件夹创建成功");
        }else{
            System.out.println("dir is exists");
        }
        file = new File(filePath);
        if(!file.isFile()){
            try {
                file.createNewFile();
                System.out.println(filePath+"文件创建成功");
                BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(filePath));
                bufferedWriter.write("hello word 陈正兵");
                bufferedWriter.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }else {
            System.out.println("文件己存在");
        }
    }