java的io简单操作

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import java.io.*;/** * Created by bruce on 2017/2/15. */public class Test {    public static void main(String[] args) {        File file = createNewFile();        String content = "hello world";//        writeStrToFile(file, content);        String readStr = readStrFromFile(file);        System.out.println(readStr);    }    /**     * 从file读取字符串     *     * @param file     * @return     */    private static String readStrFromFile(File file) {        String content = null;        if (file.exists()) {            FileInputStream fileInputStream = null;            try {                fileInputStream = new FileInputStream(file);                //创建一个长度为1024的竹筒                byte[] bbuf = new byte[1024];                //用于保存实际读取的字节数                int hasRead = 0;                //使用循环来重复“取水”的过程                while ((hasRead = fileInputStream.read(bbuf)) > 0) {                    //取出"竹筒"中(字节),将字节数组转成字符串输入                    content = new String(bbuf, 0, hasRead);                    System.out.println(content);                }            } catch (FileNotFoundException e) {                e.printStackTrace();            } catch (IOException e) {                e.printStackTrace();            } finally {                try {                    fileInputStream.close();                } catch (IOException e) {                    e.printStackTrace();                }            }        } else {            new Throwable("文件不存在");        }        return content;    }    /**     * 在本地创建一个txt文件     *     * @return     */    private static File createNewFile() {        File file = new File("e:\\java", "yang.txt");        if (!file.exists()) {            try {                file.createNewFile();            } catch (IOException e) {                e.printStackTrace();            }        }        return file;    }    /**     * 往文件里面写入字符串     *     * @param file     * @param content     */    private static void writeStrToFile(File file, String content) {        byte[] bytes = null;        //建立输出字节流        FileOutputStream fos = null;        try {            bytes = content.getBytes();            fos = new FileOutputStream(file);            //用FileOutputStream 的write方法写入字节数组            fos.write(bytes);            System.out.println("写入成功");        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }finally {            //为了节省IO流的开销，需要关闭            try {                fos.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }}
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