我的json文件
{"VisitorsList":[{"VisitorID":"09005451","VisitorName":" xxxx","VisitorPhon":"","VisitorAddr":"xxxx","GeoCode":"","AutoKey":1},{"VisitorID":"09005468","VisitorName":"xxxxxx","VisitorPhon":"09005468","VisitorAddr":"xxxx","GeoCode":"","AutoKey":2}]}
我想阅读并将此文件中的信息显示给ListView
我的VisitorsListActivity是：
public class VisitorsListActivity extends AppCompatActivity {
public ListView lstVisitors;
static VisitorsList visitorsList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.visitor_list);
try {
//********************************** COMELETE THIS SECTION *********************************************
new JsonHelper.GetJsonData(new JsonHelper.GetJsonData.AsyncResponse() {
@Override
public void processFinish(String output) {
try {
if (output == null) output = "";
if (output.equals("")) {
Toast.makeText(getApplicationContext(),
"No Visitor Founded",
Toast.LENGTH_LONG)
.show();
return;
}
//960105--------------------
else if (output.equals("401")) {
Toast.makeText(getApplicationContext(),
"Error 401",
Toast.LENGTH_LONG)
.show();
return;
}
//--------------------------------------
Log.i("LOG", "output" + output);
Gson gson = new Gson();
output = output.substring(1, output.length() - 1);
/*Toast.makeText(getApplicationContext(),
output,
Toast.LENGTH_LONG)
.show();*/
visitorsList = new VisitorsList();
visitorsList = gson.fromJson(output, VisitorsList.class);
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(getApplicationContext(),
"exception",
Toast.LENGTH_LONG)
.show();
}
}
}).execute("http://192.168.1.162:8014/api/Visitors");
//************************************ visitor list is null :| *******************************************
/*if( visitorsList == null) {
Toast.makeText(getApplicationContext(),
"data is nul",
Toast.LENGTH_LONG)
.show();
}*/
AdapterVisitor customAdapter = new AdapterVisitor(this, R.layout.visitor_list, visitorsList.VisitorsList);
customAdapter.notifyDataSetChanged();
lstVisitors.setAdapter(customAdapter);
lstVisitors.requestFocus();
final ViewGroup layoutClear = (ViewGroup) findViewById(R.id.layoutClear);
layoutClear.setVisibility(View.GONE);
} catch (Exception e) {
e.getMessage();
}
} }
和VisitorsList：
public class VisitorsList {
public VisitorsList() {}
public ArrayList<Visitors> VisitorsList;}
访问者：
public class Visitors {
public String VisitorID;
public String VisitorName;
public String VisitorPhon;
public String VisitorAddr;
public String GeoCode;
public int AutoKey;}
并且始终由Gson创建的访客列表为空。我不知道也许我的问题是从json读书或者也许是访客班......
jsonhelper：
public class JsonHelper {
public static class GetJsonData extends AsyncTask<String, Void, String> {
public interface AsyncResponse {
void processFinish(String output);
}
public AsyncResponse delegate = null;
public GetJsonData(AsyncResponse delegate) {
this.delegate = delegate;
}
@Override
protected String doInBackground(String... strUrl) {
String str = strUrl[0];
URLConnection urlConn = null;
BufferedReader bufferedReader = null;
try {
URL url = new URL(str);
urlConn = url.openConnection();
urlConn.setReadTimeout(300000);
urlConn.setConnectTimeout(5000);
bufferedReader = new BufferedReader(new InputStreamReader(urlConn.getInputStream(), "utf-8"), 8);
StringBuffer stringBuffer = new StringBuffer();
String line;
while ((line = bufferedReader.readLine()) != null) {
stringBuffer.append(line);
}
String tmpJson = stringBuffer.toString().replace("\\", "");
return tmpJson;
} catch (Exception ex) {
ex.getMessage();
return null;
} finally {
if (bufferedReader != null) {
try {
bufferedReader.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
@Override
protected void onPostExecute(String response) {
delegate.processFinish(response);
}
}
public static class SetJsonData extends AsyncTask<String, Void, String> {
String responseServer;
public interface AsyncResponse {
void processFinish(String output);
}
public AsyncResponse delegate = null;
public SetJsonData(AsyncResponse delegate) {
this.delegate = delegate;
}
@Override
protected String doInBackground(String... param) {
URL url;
String response = null;
try {
url = new URL(param[0]);
HttpURLConnection conn = null;
conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(20000);
conn.setConnectTimeout(10000);//950718
conn.setRequestMethod("GET");
conn.setDoInput(true);
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(os, "UTF-8"));
writer.write(param[1]);
writer.flush();
writer.close();
os.close();
int responseCode = conn.getResponseCode();
if (responseCode == HttpsURLConnection.HTTP_OK) {
String line;
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line = br.readLine()) != null) {
response += line;
}
} else {
response = (String.valueOf(responseCode));
String line;
BufferedReader br = new BufferedReader(new InputStreamReader(conn.getErrorStream()));//950427
while ((line = br.readLine()) != null) {
}
}
return response;
} catch (IOException e1) {
e1.getMessage();
return null;
} catch (Exception e) {
e.getMessage();
return null;
}
}
@Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
try {
super.onPostExecute(result);
delegate.processFinish(result);
} catch (Exception e) {
e.getMessage();
}
}
}}
答案 0 :(得分：0)
您的访客类缺少注释。 用它来正确转换它： http://www.jsonschema2pojo.org/
答案 1 :(得分：0)
答案 2 :(得分：0)
好在第一次阅读AsyncResponse所以你正在使用异步请求是做什么的？
异步请求不会阻止客户端，因此当响应返回时它会继续执行代码，它将执行回调内部的操作。
但是您要调用customAdapter.notifyDataSetChanged();外processFinish()来调用它，或者调用Adapter方法中的processFinish工作。
答案 3 :(得分：0)
public class VisitorsList {
public VisitorsList（）{}
public ArrayList VisitorsList = new ArrayList＆lt;＆gt;（）;}
应该是这样......缺少初始化。
答案 4 :(得分：0)
VisitorsList类：
public class VisitorsList {
@SerializedName("VisitorsList")
public List<VisitorsList> VisitorsList;
public static class VisitorsList {
@SerializedName("VisitorID")
public String VisitorID;
@SerializedName("VisitorName")
public String VisitorName;
@SerializedName("VisitorPhon")
public String VisitorPhon;
@SerializedName("VisitorAddr")
public String VisitorAddr;
@SerializedName("GeoCode")
public String GeoCode;
@SerializedName("AutoKey")
public int AutoKey;
}
}
删除此行
output = output.substring(1, output.length() - 1);
并获得结果：
Gson gson = new Gson();
visitorsList=gson.fromJson(output), new TypeToken<VisitorsList>() { }.getType());
答案 5 :(得分：0)
我更改VisitorsListActivity，如下所示。并在调用适配器之前设置一个条件，以确保从json读取信息已经完成，这正常工作：
new JsonHelper.GetJsonData(new JsonHelper.GetJsonData.AsyncResponse() {
@Override
public void processFinish(String output) {
try {
if (output == null) output = "";
if (output.equals("")) {
Toast.makeText(getApplicationContext(),
"No Visitor Founded",
Toast.LENGTH_LONG)
.show();
return;
}
else if (output.equals("401")) {
Toast.makeText(getApplicationContext(),
"Error 401",
Toast.LENGTH_LONG)
.show();
return;
}
Log.i("LOG", "output" + output);
Gson gson = new Gson();
output = output.substring(1, output.length() - 1);
try {
visitorsList = new VisitorsList();
visitorsList = gson.fromJson(output, VisitorsList.class);
if(visitorsList != null) {
d.cancel();
adapter = new AdapterVisitor(visitorsList.VisitorsList);
adapter.notifyDataSetChanged();
lstVisitors.setAdapter(adapter);
lstVisitors.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// ******
Object o = lstVisitors.getItemAtPosition(position);
Intent i = new Intent(getApplicationContext(),DateSelectorActivity.class);
Visitors v = (Visitors) o;
i.putExtra("VisitorID", v.VisitorID);
startActivity(i);
}
});
}
}catch (Exception e) {
Log.i("LOG", getAssets().toString() + "exception" + e);
}
} catch (Exception e) {
e.printStackTrace();
}
}
}).execute(url);