如何在Android应用程序上从外部存储解析或读取json文件

我目前实现了从服务器（url）解析json。但是我找不到从sdcard（/Download/example.json）解析json的方法。有人能帮我解决这个问题/更改这个代码吗

我用asyncTask来完成这个任务。示例教程或示例代码更受欢迎。（对不起，我的英语不好。）

public类主扩展活动{
私人文本视图商店显示；
专用静态字符串searchURL=”http://example.com/sample.json";
@凌驾
创建时受保护的void（Bundle savedInstanceState）{
super.onCreate（savedInstanceState）；
setContentView（R.layout.baby）；
//全班参考
shopsDisplay=（TextView）findviewbyd（R.id.tweet_-txt）；
新建GetShops（）.execute（searchURL）；
}
私有类GetShops扩展异步任务{
/*
*在后台执行抓取任务
*-通过执行方法接收搜索URL
*/
@凌驾
受保护的字符串背景（字符串…shopsURL）{
//开始生成结果，该结果将是json字符串
StringBuilder shopsFeedBuilder=新建StringBuilder（）；
//应仅为一个URL，接收数组
for（字符串搜索URL:shopsURL）{
HttpClient shopsClient=新的默认HttpClient（）；
试一试{
//传递要获取的搜索URL字符串
HttpGet shopsGet=新的HttpGet（搜索URL）；
//执行请求
HttpResponse shopsResponse=shopsClient.execute（shopsGet）；
//检查状态，仅在确定时继续
StatusLine searchStatus=shopsResponse.getStatusLine（）；
if（searchStatus.getStatusCode（）==200）{
//得到回应
HttpEntity shopsEntity=shopsResponse.getEntity（）；
InputStream shopsContent=shopsEntity.getContent（）；
//处理结果
InputStreamReader shopsInput=新的InputStreamReader（shopsContent）；
BufferedReader shopsReader=新的BufferedReader（shopsInput）；
弦线；
而（（lineIn=shopsReader.readLine（））！=null）{
shopsFeedBuilder.append（lineIn）；
}
}
其他的
shopsDisplay.setText（“哎呀，出了点问题！”）；
}
捕获（例外e）{
shopsDisplay.setText（“哎呀，出了点问题！”）；
e、 printStackTrace（）；
}
}
//返回结果字符串
return shopsFeedBuilder.toString（）；
}
/*
*处理搜索查询的结果
*-接收包含搜索词的代表商店的JSON字符串
*/
受保护的void onPostExecute（字符串结果）{
//开始准备要显示的结果字符串
StringBuilder shopsResultBuilder=新StringBuilder（）；
试一试{
//从结果中获取JSONObject
JSONObject resultObject=新的JSONObject（结果）；
//获取检索到的JSONObject中包含的JSONArray-“结果”
JSONArray shopsArray=resultObject.getJSONArray（“shops”）；
//循环浏览shops数组中的每个项目
对于（int t=0；t0）
shopsDisplay.setText（shopsResultBuilder.toString（））；
其他的
shopsDisplay.setText（“对不起，没有找到可供您搜索的店铺！”）；
}
}
}

对于

JSONObject

，使用标准Java文件I/O将文件读入

字符串

，然后将其传递给

JSONObject

构造函数

但是，如果您有一个大的JSON文件，您可能希望切换到其他JSON解析器（例如），这可能会给您提供不同的选项（例如，使用

FileReader

和

JsonReader

）

public class Main extends Activity {

        private TextView shopsDisplay;
        private static String searchURL = "http://example.com/sample.json";

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.baby);
            //reference throughout class
            shopsDisplay = (TextView)findViewById(R.id.tweet_txt);
            new GetShops().execute(searchURL);
        }
private class GetShops extends AsyncTask<String, Void, String> {
            /*
             * Carry out fetching task in background
             * - receives search URL via execute method
             */
            @Override
            protected String doInBackground(String... shopsURL) {
                //start building result which will be json string
                StringBuilder shopsFeedBuilder = new StringBuilder();
                //should only be one URL, receives array
                for (String searchURL : shopsURL) {
                    HttpClient shopsClient = new DefaultHttpClient();
                    try {
                        //pass search URL string to fetch
                        HttpGet shopsGet = new HttpGet(searchURL);
                        //execute request
                        HttpResponse shopsResponse = shopsClient.execute(shopsGet);
                        //check status, only proceed if ok
                        StatusLine searchStatus = shopsResponse.getStatusLine();
                        if (searchStatus.getStatusCode() == 200) {
                            //get the response
                            HttpEntity shopsEntity = shopsResponse.getEntity();
                            InputStream shopsContent = shopsEntity.getContent();
                            //process the results
                            InputStreamReader shopsInput = new InputStreamReader(shopsContent);
                            BufferedReader shopsReader = new BufferedReader(shopsInput);
                            String lineIn;
                            while ((lineIn = shopsReader.readLine()) != null) {
                                shopsFeedBuilder.append(lineIn);
                            }
                        }
                        else
                            shopsDisplay.setText("Whoops - something went wrong!");
                    }
                    catch(Exception e){ 
                        shopsDisplay.setText("Whoops - something went wrong!");
                        e.printStackTrace(); 
                    }
                }
                //return result string
                return shopsFeedBuilder.toString();
            }
            /*
             * Process result of search query
             * - this receives JSON string representing shops with search term included
             */
            protected void onPostExecute(String result) {
                //start preparing result string for display
                StringBuilder shopsResultBuilder = new StringBuilder();
                try {
                    //get JSONObject from result
                    JSONObject resultObject = new JSONObject(result);
                    //get JSONArray contained within the JSONObject retrieved - "results"
                    JSONArray shopsArray = resultObject.getJSONArray("shops");
                    //loop through each item in the shops array
                    for (int t=0; t<shopsArray.length(); t++) {
                        //each item is a JSONObject
                        JSONObject shopsObject = shopsArray.getJSONObject(t);
                        //for if condition
                        String id = (String) shopsObject.get("id");
                        //get the name and description for each shops
                        if (id.equals("550")){
                        shopsResultBuilder.append(shopsObject.getString("name")+": ");
                        shopsResultBuilder.append(shopsObject.get("description")+"\n\n");
                        }
                    }
                }
                catch (Exception e) {
                    shopsDisplay.setText("Whoops - something went wrong!");
                    e.printStackTrace();
                }
                //check result exists
                if(shopsResultBuilder.length()>0)
                    shopsDisplay.setText(shopsResultBuilder.toString());
                else
                    shopsDisplay.setText("Sorry - no shops found for your search!");
            }
        }


}