Android 如何从 SD 卡读取 json 文件（文本文件）并将数据显示到 textview
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Android How can I read json file(text file) from SD Card and display data into textview
提问by Farhan Shah
I have the following textfile into my SdCard.now i want to parse this file via Json parser,and i want to parse and read this file and display data into my textview,how i can do this?
我有以下文本文件到我的 SdCard.now 我想通过 Json 解析器解析这个文件，我想解析和读取这个文件并将数据显示到我的文本视图中，我该怎么做？
{
"data": [
{
"id": "1",
"title": "Farhan Shah",
"duration": 10,
},
{
"id": "2",
"title": "Noman Shah",
"duration": 10,
},
{
"id": "3",
"title": "Ahmad Shah",
"duration": 10,
},
{
"id": "4",
"title": "Mohsin Shah",
"duration": 10,
},
{
"id": "5",
"title": "Haris Shah",
"duration": 10,
}
]
}
This is the code:
这是代码：
File sdcard = Environment.getExternalStorageDirectory();
//Get the text file
File file = new File(sdcard,"textarabics.txt");
String UTF8 = "utf8";
int BUFFER_SIZE = 8192;
//Read text from file
StringBuilder text = new StringBuilder();
i get the file,but now i have no idea that how i can parse the data?
我得到了文件，但现在我不知道如何解析数据？
回答by Smile2Life
Read the JSON file using Filefrom SD card and use JSONObjectto parse it.
使用SD 卡中的File读取 JSON 文件并使用JSONObject 对其进行解析。
Here a starting code:
这是一个起始代码：
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
public class ReadJsonFile {
public ReadFile (){
try {
File yourFile = new File(Environment.getExternalStorageDirectory(), "path/to/the/file/inside_the_sdcard/textarabics.txt");
FileInputStream stream = new FileInputStream(yourFile);
String jsonStr = null;
try {
FileChannel fc = stream.getChannel();
MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
jsonStr = Charset.defaultCharset().decode(bb).toString();
}
catch(Exception e){
e.printStackTrace();
}
finally {
stream.close();
}
/* String jsonStr = "{\n\"data\": [\n {\n \"id\": \"1\",\n \"title\": \"Farhan Shah\",\n \"duration\": 10\n },\n {\n \"id\": \"2\",\n \"title\": \"Noman Shah\",\n \"duration\": 10\n },\n {\n \"id\": \"3\",\n \"title\": \"Ahmad Shah\",\n \"duration\": 10\n },\n {\n \"id\": \"4\",\n \"title\": \"Mohsin Shah\",\n \"duration\": 10\n },\n {\n \"id\": \"5\",\n \"title\": \"Haris Shah\",\n \"duration\": 10\n }\n ]\n\n}\n";
*/
JSONObject jsonObj = new JSONObject(jsonStr);
// Getting data JSON Array nodes
JSONArray data = jsonObj.getJSONArray("data");
// looping through All nodes
for (int i = 0; i < data.length(); i++) {
JSONObject c = data.getJSONObject(i);
String id = c.getString("id");
String title = c.getString("title");
String duration = c.getString("duration");
//use > int id = c.getInt("duration"); if you want get an int
// tmp hashmap for single node
HashMap<String, String> parsedData = new HashMap<String, String>();
// adding each child node to HashMap key => value
parsedData.put("id", id);
parsedData.put("title", title);
parsedData.put("duration", duration);
// do what do you want on your interface
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
Ddon't forget to add read storage on your mainfest:
不要忘记在 mainfest 上添加读取存储：
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
回答by Hari Babu Mandala
Following may be useful, which I have taken from android developer site.
以下可能有用，这是我从 android 开发者网站上获取的。
In order to read or write files on the external storage, your app must acquire the READ_EXTERNAL_STORAGEor WRITE_EXTERNAL_STORAGEsystem permissions.
为了读取或写入外部存储上的文件，您的应用程序必须获得 READ_EXTERNAL_STORAGE或WRITE_EXTERNAL_STORAGE系统权限。
You can set the permissions in your manifest file like this:
您可以在清单文件中设置权限，如下所示：
<manifest ...>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
...
</manifest>
Here are a couple methods you can use to check the availability:
您可以使用以下几种方法来检查可用性：
/* Checks if external storage is available for read and write */
public boolean isExternalStorageWritable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state)) {
return true;
}
return false;
}
/* Checks if external storage is available to at least read */
public boolean isExternalStorageReadable() {
String state = Environment.getExternalStorageState();
if (Environment.MEDIA_MOUNTED.equals(state) ||
Environment.MEDIA_MOUNTED_READ_ONLY.equals(state)) {
return true;
}
return false;
}
Read the file content as given below. After that you can process,
阅读下面给出的文件内容。之后就可以处理了
final File file = new File(Environment.getExternalStorageDirectory()
.getAbsolutePath(), filename);
回答by mohammad rababah
get the file contents like this:
获取文件内容如下：
File yourFile = new File("/mnt/extSdCard/test.json");
FileInputStream stream = new FileInputStream(yourFile);
String jString = null;
try {
FileChannel fc = stream.getChannel();
MappedByteBuffer bb = fc.map(FileChannel.MapMode.READ_ONLY, 0, fc.size());
/* Instead of using default, pass in a decoder. */
jString = Charset.defaultCharset().decode(bb).toString();
}
finally {
stream.close();
}
parse and add to listview:
解析并添加到列表视图：
String[] from = new String[] {"title"};
int[] to = new int[] { R.id.name};
List<HashMap<String, String>> fillMaps = new ArrayList<HashMap<String, String>>();
try
{
JSONArray names = new JSONArray(jsonString);
Log.i("MyList","Number of names " + names.length());
for (int j = 0; j < names.length(); j++)
{
JSONObject jsonObject = names.getJSONObject(j);
HashMap<String, String> map = new HashMap<String, String>();
map.put("title", jsonObject.getString("title"));
fillMaps.add(map);
}
}
catch (Exception e)
{
e.printStackTrace();
}
SimpleAdapter adapter = new SimpleAdapter(context, fillMaps, R.layout.result, from, to);
mListView.setAdapter(adapter);
Here mListView is your predefined ListView.
这里 mListView 是您预定义的 ListView。
