android 文件读写

android 文件读写
读取：

public static String _getJsonString(String fileName)

        throws IOException {    if ((fileName == null) || fileName.isEmpty()) {        return "";    }    String retString = "";    FileInputStream fis = null;    String state = Environment.getExternalStorageState();    if (state.equals(Environment.MEDIA_MOUNTED)) {        File file = new File(Environment.getExternalStorageDirectory()                + "/" + fileName + ".json");        if (file.exists()) {            fis = new FileInputStream(file);            byte[] buffer = new byte[fis.available()];            fis.read(buffer);            fis.close();            retString = new String(buffer);        } else {        }    }    return retString;}

写：

public static void saveSettingFile(String fileName, String content) {

    FileOutputStream fos = null;    String state = Environment.getExternalStorageState();    if (state.equals(Environment.MEDIA_MOUNTED)) {        File file = new File(Environment.getExternalStorageDirectory()                + "/" + fileName + ".json");        try {            fos = new FileOutputStream(file);            byte[] buffer = content.getBytes();            fos.write(buffer);            fos.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}

Gson 读写：

public static void saveServerInfo(String fileName, String content) {

    FileOutputStream fos = null;    String state = Environment.getExternalStorageState();    if (state.equals(Environment.MEDIA_MOUNTED)) {        File file = new File(Environment.getExternalStorageDirectory()                + "/" + fileName + ".json");        try {            fos = new FileOutputStream(file);            byte[] buffer = content.getBytes();            fos.write(buffer);            fos.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }}public static ServerInfo getServerInfo(String fileName)        throws IOException {    ServerInfo serverInfo = new ServerInfo();    if ((fileName == null) || fileName.isEmpty()) {        serverInfo = null;        return serverInfo;    }    FileInputStream fis = null;    String state = Environment.getExternalStorageState();    if (state.equals(Environment.MEDIA_MOUNTED)) {        File file = new File(Environment.getExternalStorageDirectory()                + "/" + fileName + ".json");        if (file.exists()) {            fis = new FileInputStream(file);            byte[] buffer = new byte[fis.available()];            fis.read(buffer);            fis.close();            Gson gson = new Gson();            serverInfo = gson.fromJson(new String(buffer),                    ServerInfo.class);        } else {            serverInfo = null;        }    }    return serverInfo;}

调用：

public void onSetIPAndPort(View view) {

    ServerInfo serverInfo = new ServerInfo();    try {        serverInfo = JsonFileWriteAndRead.getServerInfo("videochat");    } catch (IOException e) {        e.printStackTrace();    }    //写入ip和端口    String ip = ipSet.getText().toString();    String port = portSet.getText().toString();    serverInfo.setIpString(ip);    serverInfo.setPortString(port);    Gson gson = new Gson();    if (ip.isEmpty() || port.isEmpty()) {        Toast.makeText(this, "地址或端口为空", Toast.LENGTH_SHORT).show();    } else {        JsonFileWriteAndRead.saveServerInfo("videochat", gson.toJson(serverInfo));        Toast.makeText(this, "地址和端口已经写入文件", Toast.LENGTH_SHORT).show();    }}

作者：小新110
来源：CSDN
原文：https://blog.csdn.net/cau_eric/article/details/90410761
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