我正在尝试解析从我的 Android 应用程序中的 URL 获取的 JSON 结果...
我在 Internet 上尝试了一些示例，但无法使其正常工作。JSON 数据如下所示：
[
{
"city_id": "1",
"city_name": "Noida"
},
{
"city_id": "2",
"city_name": "Delhi"
},
{
"city_id": "3",
"city_name": "Gaziyabad"
},
{
"city_id": "4",
"city_name": "Gurgaon"
},
{
"city_id": "5",
"city_name": "Gr. Noida"
}
]
获取 URL 并解析 JSON 数据的最简单方法是什么在列表视图中显示
您可以使用AsyncTask，您必须进行自定义以满足您的需求，但类似于以下内容
异步任务具有三种主要方法：
onPreExecute()- 最常用于设置和启动进度对话框
doInBackground()- 建立连接并从服务器接收响应（不要尝试将响应值分配给 GUI 元素，这是一个常见错误，无法在后台线程中完成）。
onPostExecute()- 这里我们脱离了后台线程，所以我们可以对响应数据进行用户界面操作，或者简单地将响应分配给特定的变量类型。首先，我们将启动类，初始化 aString以将结果保存在方法之外但在类内部，然后运行该onPreExecute()方法，设置一个简单的进度对话框。
class MyAsyncTask extends AsyncTask<String, String, Void> {
private ProgressDialog progressDialog = new ProgressDialog(MainActivity.this);
InputStream inputStream = null;
String result = "";
protected void onPreExecute() {
progressDialog.setMessage("Downloading your data...");
progressDialog.show();
progressDialog.setOnCancelListener(new OnCancelListener() {
public void onCancel(DialogInterface arg0) {
MyAsyncTask.this.cancel(true);
}
});
}
然后我们需要设置连接以及我们希望如何处理响应：
@Override
protected Void doInBackground(String... params) {
String url_select = "http://yoururlhere.com";
ArrayList<NameValuePair> param = new ArrayList<NameValuePair>();
try {
// Set up HTTP post
// HttpClient is more then less deprecated. Need to change to URLConnection
HttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url_select);
httpPost.setEntity(new UrlEncodedFormEntity(param));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
// Read content & Log
inputStream = httpEntity.getContent();
} catch (UnsupportedEncodingException e1) {
Log.e("UnsupportedEncodingException", e1.toString());
e1.printStackTrace();
} catch (ClientProtocolException e2) {
Log.e("ClientProtocolException", e2.toString());
e2.printStackTrace();
} catch (IllegalStateException e3) {
Log.e("IllegalStateException", e3.toString());
e3.printStackTrace();
} catch (IOException e4) {
Log.e("IOException", e4.toString());
e4.printStackTrace();
}
// Convert response to string using String Builder
try {
BufferedReader bReader = new BufferedReader(new InputStreamReader(inputStream, "utf-8"), 8);
StringBuilder sBuilder = new StringBuilder();
String line = null;
while ((line = bReader.readLine()) != null) {
sBuilder.append(line + "\n");
}
inputStream.close();
result = sBuilder.toString();
} catch (Exception e) {
Log.e("StringBuilding & BufferedReader", "Error converting result " + e.toString());
}
} // protected Void doInBackground(String... params)
最后，在这里我们将解析返回，在这个例子中它是一个 JSON 数组，然后关闭对话框：
protected void onPostExecute(Void v) {
//parse JSON data
try {
JSONArray jArray = new JSONArray(result);
for(i=0; i < jArray.length(); i++) {
JSONObject jObject = jArray.getJSONObject(i);
String name = jObject.getString("name");
String tab1_text = jObject.getString("tab1_text");
int active = jObject.getInt("active");
} // End Loop
this.progressDialog.dismiss();
} catch (JSONException e) {
Log.e("JSONException", "Error: " + e.toString());
} // catch (JSONException e)
} // protected void onPostExecute(Void v)
} //class MyAsyncTask extends AsyncTask<String, String, Void>
我建议使用该JSONParser课程。它非常易于使用。
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
// function get json from url
// by making HTTP POST or GET method
public JSONObject makeHttpRequest(String url, String method,
List<NameValuePair> params) throws IOException {
// Making HTTP request
try {
// check for request method
if(method == "POST"){
// request method is POST
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
httpPost.setEntity(new UrlEncodedFormEntity(params));
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}else if(method == "GET"){
// request method is GET
DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
String paramString = URLEncodedUtils.format(params, "utf-8");
url += "?" + paramString;
HttpGet httpGet = new HttpGet(url);
HttpResponse httpResponse = httpClient.execute(httpGet);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
}
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (Exception ex) {
Log.d("Networking", ex.getLocalizedMessage());
throw new IOException("Error connecting");
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
然后在您的应用程序中，创建此类的一个实例。如果需要，您可能需要传递构造函数“GET”或“POST”。
public JSONParser jsonParser = new JSONParser();
try {
// Building Parameters ( you can pass as many parameters as you want)
List<NameValuePair> params = new ArrayList<NameValuePair>();
params.add(new BasicNameValuePair("name", name));
params.add(new BasicNameValuePair("age", 25));
// Getting JSON Object
JSONObject json = jsonParser.makeHttpRequest(YOUR_URL, "POST", params);
} catch (JSONException e) {
e.printStackTrace();
}
JSONObject(html).getString("name");
如何获取html字符串：
使用 android 发出 HTTP 请求
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.HashMap;
public class GetJsonFromUrl {
String url = null;
public GetJsonFromUrl(String url) {
this.url = url;
}
public String GetJsonData() {
try {
URL Url = new URL(url);
HttpURLConnection connection = (HttpURLConnection) Url.openConnection();
InputStream is = connection.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
StringBuilder sb = new StringBuilder();
String line;
while ((line = br.readLine()) != null) {
sb.append(line);
}
line = sb.toString();
connection.disconnect();
is.close();
sb.delete(0, sb.length());
return line;
} catch (Exception e) {
return null;
}
}
}
这个类用于发布数据
import android.util.Log;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.Map;
import javax.net.ssl.HttpsURLConnection;
/**
* Created by user on 11/2/16.
*/
public class sendDataToServer {
public String postdata(String requestURL,HashMap<String,String> postDataParams){
try {
String response = "";
URL url = new URL(requestURL);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(15000);
conn.setConnectTimeout(15000);
conn.setRequestMethod("POST");
conn.setDoInput(true);
conn.setDoOutput(true);
OutputStream os = conn.getOutputStream();
BufferedWriter writer = new BufferedWriter(
new OutputStreamWriter(os, "UTF-8"));
writer.write(getPostDataString(postDataParams));
writer.flush();
writer.close();
os.close();
String line;
BufferedReader br=new BufferedReader(new InputStreamReader(conn.getInputStream()));
while ((line=br.readLine()) != null) {
response+=line;
}
Log.d("test", response);
return response;
}catch (Exception e){
return e.toString();
}
}
public String postjson(String url,String json){
try {
URL obj = new URL(url);
HttpURLConnection con= (HttpURLConnection) obj.openConnection();
//add reuqest header
con.setRequestMethod("POST");
con.setRequestProperty("Accept", "application/json");
String urlParameters = ""+json;
// Send post request
con.setDoOutput(true);
con.setDoInput(true);
con.setRequestProperty("Content-Type", "application/json");
OutputStreamWriter wr = new OutputStreamWriter(con.getOutputStream());
wr.write(urlParameters);
wr.flush();
wr.close();
int responseCode = con.getResponseCode();
System.out.println("\nSending 'POST' request to URL : " + url);
System.out.println("Post parameters : " + urlParameters);
System.out.println("Response Code : " + responseCode);
BufferedReader in = new BufferedReader(
new InputStreamReader(con.getInputStream()));
String inputLine;
StringBuffer response = new StringBuffer();
while ((inputLine = in.readLine()) != null) {
response.append(inputLine);
}
in.close();
//print result
System.out.println(response.toString());
return response.toString();
}catch(Exception e){
return e.toString();
}
}
private String getPostDataString(HashMap<String, String> params) throws UnsupportedEncodingException {
StringBuilder result = new StringBuilder();
boolean first = true;
for(Map.Entry<String, String> entry : params.entrySet()){
if (first)
first = false;
else
result.append("&");
result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
result.append("=");
result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
}
return result.toString();
}
/* public String postdata(String url) {
}*/
}
尝试：
// your get json request to server..
HttpResponse response = httpClient.execute(httpPost);
HttpEntity entity = response.getEntity();
if(entity != null){
JSONObject respObject = new JSONObject(EntityUtils.toString(entity));
String active = respObject.getString("active");
String name = respObject.getString("name");
String tab1_text = respObject.getString("tab1_text");
//....
}
else{
//Do something here...
}
请参阅此示例以获取和解析来自服务器的 json 响应：
http://adblogcat.com/parse-json-data-from-a-web-server-and-display-on-listview/
HttpClient client = new DefaultHttpClient();
HttpGet request = new HttpGet();
request.setURI(new URI(url));
HttpResponse response = client.execute(request);
BufferedReader in = new BufferedReader(new InputStreamReader(response
.getEntity().getContent()));
String line = "";
while ((line = in.readLine()) != null) {
JSONObject jObject = new JSONObject(line);
if (jObject.has("name")) {
String temp = jObject.getString("name");
Log.e("name",temp);
}
}