Question

如何在Android中解析JSON Feed？

Answer 1

注意：这个答案自2013年以来一直没有更新。建议的下载json的方法不再推荐用于android了，因为http客户端已从api 23中删除了sdk。
但是，下面的解析逻辑仍适用

Android拥有解析内置json所需的所有工具。示例如下，不需要GSON或类似的东西。

获取您的JSON：

DefaultHttpClient   httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost(http://someJSONUrl/jsonWebService);
// Depends on your web service
httppost.setHeader("Content-type", "application/json");

InputStream inputStream = null;
String result = null;
try {
    HttpResponse response = httpclient.execute(httppost);           
    HttpEntity entity = response.getEntity();

    inputStream = entity.getContent();
    // json is UTF-8 by default
    BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);
    StringBuilder sb = new StringBuilder();

    String line = null;
    while ((line = reader.readLine()) != null)
    {
        sb.append(line + "\n");
    }
    result = sb.toString();
} catch (Exception e) { 
    // Oops
}
finally {
    try{if(inputStream != null)inputStream.close();}catch(Exception squish){}
}

现在你有了JSON，那又怎么样？

创建JSONObject：

JSONObject jObject = new JSONObject(result);

获取特定字符串

String aJsonString = jObject.getString("STRINGNAME");

获取特定布尔值

boolean aJsonBoolean = jObject.getBoolean("BOOLEANNAME");

获取特定整数

int aJsonInteger = jObject.getInt("INTEGERNAME");

获取特定的长

long aJsonLong = jObject.getLong("LONGNAME");

获取特定的双重

double aJsonDouble = jObject.getDouble("DOUBLENAME");

获取特定的JSONArray：

JSONArray jArray = jObject.getJSONArray("ARRAYNAME");

从阵列中获取项目

for (int i=0; i < jArray.length(); i++)
{
    try {
        JSONObject oneObject = jArray.getJSONObject(i);
        // Pulling items from the array
        String oneObjectsItem = oneObject.getString("STRINGNAMEinTHEarray");
        String oneObjectsItem2 = oneObject.getString("anotherSTRINGNAMEINtheARRAY");
    } catch (JSONException e) {
        // Oops
    }
}

Answer 2

编写JSON解析器类

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";

    // constructor
    public JSONParser() {}

    public JSONObject getJSONFromUrl(String url) {

        // Making HTTP request
        try {
            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost(url);

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent();

        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        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;

    }
}

解析JSON数据
一旦你创建了解析器类，下一件事就是知道如何使用该类。下面我将解释如何使用解析器类解析json（在此示例中使用）。

2.1。将所有这些节点名称存储在变量中：在联系人json中，我们有名称，电子邮件，地址，性别和电话号码等项目。首先，将所有这些节点名称存储在变量中。打开主活动类并声明将所有节点名称存储在静态变量中。

// url to make request
private static String url = "http://api.9android.net/contacts";

// JSON Node names
private static final String TAG_CONTACTS = "contacts";
private static final String TAG_ID = "id";
private static final String TAG_NAME = "name";
private static final String TAG_EMAIL = "email";
private static final String TAG_ADDRESS = "address";
private static final String TAG_GENDER = "gender";
private static final String TAG_PHONE = "phone";
private static final String TAG_PHONE_MOBILE = "mobile";
private static final String TAG_PHONE_HOME = "home";
private static final String TAG_PHONE_OFFICE = "office";

// contacts JSONArray
JSONArray contacts = null;

2.2。使用解析器类获取JSONObject并循环遍历每个json项。下面我创建一个JSONParser类的实例并使用for循环我循环遍历每个json项目，最后将每个json数据存储在变量中。

// Creating JSON Parser instance
JSONParser jParser = new JSONParser();

// getting JSON string from URL
JSONObject json = jParser.getJSONFromUrl(url);

    try {
    // Getting Array of Contacts
    contacts = json.getJSONArray(TAG_CONTACTS);

    // looping through All Contacts
    for(int i = 0; i < contacts.length(); i++){
        JSONObject c = contacts.getJSONObject(i);

        // Storing each json item in variable
        String id = c.getString(TAG_ID);
        String name = c.getString(TAG_NAME);
        String email = c.getString(TAG_EMAIL);
        String address = c.getString(TAG_ADDRESS);
        String gender = c.getString(TAG_GENDER);

        // Phone number is agin JSON Object
        JSONObject phone = c.getJSONObject(TAG_PHONE);
        String mobile = phone.getString(TAG_PHONE_MOBILE);
        String home = phone.getString(TAG_PHONE_HOME);
        String office = phone.getString(TAG_PHONE_OFFICE);

    }
} catch (JSONException e) {
    e.printStackTrace();
}

Answer 3

我为您编写了一个简单的示例并注释了源代码。该示例显示了如何抓取实时json并解析为JSONObject以进行详细信息提取：

try{
    // Create a new HTTP Client
    DefaultHttpClient defaultClient = new DefaultHttpClient();
    // Setup the get request
    HttpGet httpGetRequest = new HttpGet("http://example.json");

    // Execute the request in the client
    HttpResponse httpResponse = defaultClient.execute(httpGetRequest);
    // Grab the response
    BufferedReader reader = new BufferedReader(new InputStreamReader(httpResponse.getEntity().getContent(), "UTF-8"));
    String json = reader.readLine();

    // Instantiate a JSON object from the request response
    JSONObject jsonObject = new JSONObject(json);

} catch(Exception e){
    // In your production code handle any errors and catch the individual exceptions
    e.printStackTrace();
}

在您JSONObject之后，请参阅SDK，了解有关如何提取所需数据的详细信息。

如何解析Android中的JSON？

3 个答案: