Android开发中常用到的工具类——读写文件类

/**
     * 判断SD卡是否可用
     * @return SD卡可用返回true
     */
    public static boolean hasSdcard() {
        String status = Environment.getExternalStorageState();
        return Environment.MEDIA_MOUNTED.equals(status);
    }

    /**
     * 读取文件的内容
     * <br>
     * 默认utf-8编码
     * @param filePath 文件路径
     * @return 字符串
     * @throws IOException
     */
    public static String readFile(String filePath) throws IOException {
        return readFile(filePath, "utf-8");
    }

    /**
     * 读取文件的内容
     * @param filePath 文件目录
     * @param charsetName 字符编码
     * @return String字符串
     */
    public static String readFile(String filePath, String charsetName)
            throws IOException {
        if (TextUtils.isEmpty(filePath))
            return null;
        if (TextUtils.isEmpty(charsetName))
            charsetName = "utf-8";
        File file = new File(filePath);
        StringBuilder fileContent = new StringBuilder("");
        if (file == null || !file.isFile())
            return null;
        BufferedReader reader = null;
        try {
            InputStreamReader is = new InputStreamReader(new FileInputStream(
                    file), charsetName);
            reader = new BufferedReader(is);
            String line = null;
            while ((line = reader.readLine()) != null) {
                if (!fileContent.toString().equals("")) {
                    fileContent.append("\r\n");
                }
                fileContent.append(line);
            }
            return fileContent.toString();
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 读取文本文件到List字符串集合中(默认utf-8编码)
     * @param filePath 文件目录
     * @return 文件不存在返回null，否则返回字符串集合
     * @throws IOException
     */
    public static List<String> readFileToList(String filePath)
            throws IOException {
        return readFileToList(filePath, "utf-8");
    }

    /**
     * 读取文本文件到List字符串集合中
     * @param filePath 文件目录
     * @param charsetName 字符编码
     * @return 文件不存在返回null，否则返回字符串集合
     */
    public static List<String> readFileToList(String filePath,
                                              String charsetName) throws IOException {
        if (TextUtils.isEmpty(filePath))
            return null;
        if (TextUtils.isEmpty(charsetName))
            charsetName = "utf-8";
        File file = new File(filePath);
        List<String> fileContent = new ArrayList<String>();
        if (file == null || !file.isFile()) {
            return null;
        }
        BufferedReader reader = null;
        try {
            InputStreamReader is = new InputStreamReader(new FileInputStream(
                    file), charsetName);
            reader = new BufferedReader(is);
            String line = null;
            while ((line = reader.readLine()) != null) {
                fileContent.add(line);
            }
            return fileContent;
        } finally {
            if (reader != null) {
                try {
                    reader.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }

    /**
     * 向文件中写入数据
     * @param filePath 文件目录
     * @param content 要写入的内容
     * @param append 如果为 true，则将数据写入文件末尾处，而不是写入文件开始处
     * @return 写入成功返回true， 写入失败返回false
     * @throws IOException
     */
    public static boolean writeFile(String filePath, String content,
                                    boolean append) throws IOException {
        if (TextUtils.isEmpty(filePath))
            return false;
        if (TextUtils.isEmpty(content))
            return false;
        FileWriter fileWriter = null;
        try {
            createFile(filePath);
            fileWriter = new FileWriter(filePath, append);
            fileWriter.write(content);
            fileWriter.flush();
            return true;
        } finally {
            if (fileWriter != null) {
                try {
                    fileWriter.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }


    /**
     * 向文件中写入数据<br>
     * 默认在文件开始处重新写入数据
     * @param filePath 文件目录
     * @param stream 字节输入流
     * @return 写入成功返回true，否则返回false
     * @throws IOException
     */
    public static boolean writeFile(String filePath, InputStream stream)
            throws IOException {
        return writeFile(filePath, stream, false);
    }

    /**
     * 向文件中写入数据
     * @param filePath 文件目录
     * @param stream 字节输入流
     * @param append 如果为 true，则将数据写入文件末尾处；
     *              为false时，清空原来的数据，从头开始写
     * @return 写入成功返回true，否则返回false
     * @throws IOException
     */
    public static boolean writeFile(String filePath, InputStream stream,
                                    boolean append) throws IOException {
        if (TextUtils.isEmpty(filePath))
            throw new NullPointerException("filePath is Empty");
        if (stream == null)
            throw new NullPointerException("InputStream is null");
        return writeFile(new File(filePath), stream,
                append);
    }

    /**
     * 向文件中写入数据
     * 默认在文件开始处重新写入数据
     * @param file 指定文件
     * @param stream 字节输入流
     * @return 写入成功返回true，否则返回false
     * @throws IOException
     */
    public static boolean writeFile(File file, InputStream stream)
            throws IOException {
        return writeFile(file, stream, false);
    }

    /**
     * 向文件中写入数据
     * @param file 指定文件
     * @param stream 字节输入流
     * @param append 为true时，在文件开始处重新写入数据；
     *              为false时，清空原来的数据，从头开始写
     * @return 写入成功返回true，否则返回false
     * @throws IOException
     */
    public static boolean writeFile(File file, InputStream stream,
                                    boolean append) throws IOException {
        if (file == null)
            throw new NullPointerException("file = null");
        OutputStream out = null;
        try {
            createFile(file.getAbsolutePath());
            out = new FileOutputStream(file, append);
            byte data[] = new byte[1024];
            int length = -1;
            while ((length = stream.read(data)) != -1) {
                out.write(data, 0, length);
            }
            out.flush();
            return true;
        } finally {
            if (out != null) {
                try {
                    out.close();
                    stream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
    }