Java文件操作

一、文件复制

public static void main(String[] args) {
        FileInputStream fileInput = null;
        FileOutputStream fileOutput = null;
        int length = 0;
        byte[] b = new byte[1024];//一次读取的长度
        try {
            fileInput = new FileInputStream("D:/zhang/test.png");//读取的文件
            fileOutput = new FileOutputStream("D:/zhang/test2.png");//输出的文件
            while((length = fileInput.read(b)) != -1){//length的目的在于防止最后一次读取的字节小于b长度，  
                fileOutput.write(b, 0, length);//否则会自动被填充0  
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {//关闭资源
                if(fileInput != null){
                    fileInput.close();
                }
                if(fileOutput != null){
                    fileOutput.close();
                }
            } catch (Exception e2) {
                e2.printStackTrace();
            }
        }
    }

二、使用缓冲区的文件复制

public static void main(String[] args) {
        FileInputStream fileInput = null;
        FileOutputStream fileOutput = null;
        BufferedInputStream bfInput = null;
        BufferedOutputStream bfOutput = null;
        try {
            fileInput = new FileInputStream("D:/zhang/test.png");
            fileOutput = new FileOutputStream("D:/zhang/test2.png");
            bfInput = new BufferedInputStream(fileInput);
            bfOutput = new BufferedOutputStream(fileOutput);
            int i = 0;
            byte[] b = new byte[1024];
            while((i = bfInput.read(b)) != -1){
                bfOutput.write(b, 0, i);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bfInput.close();
                bfOutput.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        
    }

三、文本文件的复制

public static void main(String[] args) {
        FileReader reader = null;
        FileWriter writer = null;
        char[] c = new char[1024];
        int i = 0;
        try {
            reader = new FileReader("D:/QA/LOG/Config-20160608.txt");
            writer = new FileWriter("D:/Config-20160608.txt" , true);//设置为true追加
            while((i = reader.read(c))!= -1){
                writer.write(c, 0, i);
                System.out.println(new String(c,0,i));//输出
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if(reader != null){
                    reader.close();
                }
                if(writer != null){
                    writer.close();
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

四、缓冲区的文本文件的复制

public static void main(String[] args) {
        FileReader reader = null;
        FileWriter writer = null;
        BufferedReader bfReader = null;
        BufferedWriter bfWrider = null;
        try {
            reader = new FileReader("D:/QA/LOG/Config-20160608.txt");
            writer = new FileWriter("D:/Config-20160608.txt",true);
            bfReader = new BufferedReader(reader);
            bfWrider = new BufferedWriter(writer);
            String i = null;
            while((i = bfReader.readLine()) != null){
                bfWrider.write(i);
                bfWrider.newLine();//换行
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                bfReader.close();
                bfWrider.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }