本文介绍了ANDROID，从 Web 服务器解析 JSON 数据并显示在 ListView 上的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在尝试显示来自 JSON url 链接的 JSON 结果.目前，当我加载时，它什么也不显示，只是空白页面.
HTH
参考:
- 如何发送HTTP请求GETJava中的/POST
- Java HttpURLConnection 发送 HTTP GET 的示例/POST 请求
- Android POST 和 GET 请求使用 HttpURLConnection 教程
I am trying to display JSON result from JSON url link. Currently when I load up, it display nothing, just blank page. This is the source where I got information about JSON.
This is my code:
public class DVLAresult extends AppCompatActivity {
public class DVLAlist extends ListActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.content_dvlaresult);
setListAdapter(new ArrayAdapter(
this,android.R.layout.simple_list_item_2,
this.populate()));
}
private ArrayList<String> populate() {
ArrayList<String> items = new ArrayList<String>();
TextView newtext = (TextView) findViewById(R.id.view_number);
try {
URL url = new URL
("https://dvlasearch.appspot.com/DvlaSearch?licencePlate=mt09nks&apikey=DvlaSearchDemoAccount");
HttpURLConnection urlConnection =
(HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// gets the server json data
BufferedReader bufferedReader =
new BufferedReader(new InputStreamReader(
urlConnection.getInputStream()));
String next;
while ((next = bufferedReader.readLine()) != null) {
JSONArray ja = new JSONArray(next);
for (int i = 0; i < ja.length(); i++) {
JSONObject jo = (JSONObject) ja.get(i);
items.add(jo.getString("text"));
}
}
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return items;
}
}
}
And this is my XML file simple_list_2.xml
<?xml version="1.0" encoding="utf-8"?>
<TwoLineListItem xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:minHeight="?attr/listPreferredItemHeight"
android:mode="twoLine"
android:paddingStart="?attr/listPreferredItemPaddingStart"
android:paddingEnd="?attr/listPreferredItemPaddingEnd">
<TextView android:id="@id/text1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:textAppearance="?attr/textAppearanceListItem" />
<TextView android:id="@id/text2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/text1"
android:layout_alignStart="@id/text1"
android:textAppearance="?attr/textAppearanceListItemSecondary" />
<TextView android:id="@id/text3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@id/text2"
android:layout_alignStart="@id/text2"
android:textAppearance="?attr/textAppearanceListItemSecondary" />
... Continue up to text18, because I have 18 fields.
</TwoLineListItem>
And this is main XML ListView
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/list"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_above="@+id/button2"
android:layout_below="@+id/view_number" />
解决方案
I happen to encounter similar problem. Here is the code that help me find resolution. Hope this will help you.
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="SEND GET REQUEST"
android:id="@+id/sendGet"
android:onClick="sendGetRequest"
android:layout_alignParentStart="true" />
<ScrollView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/scrollView"
android:layout_below="@+id/sendGet"
android:layout_centerHorizontal="true">
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Response ....."
android:id="@+id/showOutput"
android:layout_alignEnd="@+id/scrollView"
android:layout_marginEnd="34dp" />
</ScrollView>
</RelativeLayout>
MainActivity.java
import android.app.ProgressDialog;
import android.content.Context;
import android.net.Uri;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import com.google.android.gms.appindexing.Action;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class MainActivity extends AppCompatActivity {
private ProgressDialog progress;
/**
* ATTENTION: This was auto-generated to implement the App Indexing API.
* See https://g.co/AppIndexing/AndroidStudio for more information.
*/
// private GoogleApiClient client;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
// client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}
public void sendGetRequest(View View) {
new GetClass(this).execute();
}
@Override
public void onStart() {
super.onStart();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
// client.connect();
Action viewAction = Action.newAction(
Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
// Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://com.example.gunawardena.get_post_demo/http/host/path")
);
// AppIndex.AppIndexApi.start(client, viewAction);
}
@Override
public void onStop() {
super.onStop();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
Action viewAction = Action.newAction(
Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
// Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://com.example.gunawardena.get_post_demo/http/host/path")
);
// AppIndex.AppIndexApi.end(client, viewAction);
// client.disconnect();
}
private class GetClass extends AsyncTask<String, Void, Void> {
private final Context context;
public GetClass(Context c) {
this.context = c;
}
protected void onPreExecute() {
progress = new ProgressDialog(this.context);
progress.setMessage("Loading Get Method.....");
progress.show();
}
@Override
protected Void doInBackground(String... params) {
try {
final TextView outputView = (TextView) findViewById(R.id.showOutput);
URL url = new URL("https://dvlasearch.appspot.com/DvlaSearch?licencePlate=mt09nks&apikey=DvlaSearchDemoAccount");
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.setRequestMethod("GET");
connection.setRequestProperty("USER-AGENT", "Mozilla/5.0");
connection.setRequestProperty("ACCEPT-LANGUAGE", "en-US,en;0.5");
int responseCode = connection.getResponseCode();
final StringBuilder output = new StringBuilder("Request URL " + url);
output.append(System.getProperty("line.separator") + "Response Code " + responseCode);
output.append(System.getProperty("line.separator") + "Type " + "GET");
BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream()));
String line = "";
StringBuilder responseOutput = new StringBuilder();
System.out.println("output===============" + br);
while ((line = br.readLine()) != null) {
responseOutput.append(line);
}
br.close();
output.append(System.getProperty("line.separator") + "Response " + System.getProperty("line.separator") + System.getProperty("line.separator") + responseOutput.toString());
MainActivity.this.runOnUiThread(new Runnable() {
@Override
public void run() {
outputView.setText(output);
progress.dismiss();
}
});
} catch (MalformedURLException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
}
}
Output on the Emulator
HTH
References:
- How to send HTTP request GET/POST in Java
- Java HttpURLConnection Example to send HTTP GET/POST Requests
- Android POST and GET Request using HttpURLConnection Tutorial
这篇关于ANDROID，从 Web 服务器解析 JSON 数据并显示在 ListView 上的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！