如何在Android中解析JSON？

如何在Android中解析JSON提要？

我为您编写了一个简单的示例，并对源代码进行了注释。该示例显示了如何获取实时json并解析为JSONObject以进行细节提取：

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();
}

---

一旦有了JSONObject，请参阅，以获取有关如何提取所需数据的详细信息。

Android拥有解析内置json所需的所有工具。下面是一个例子，不需要GSON或类似的东西

获取您的JSON：

假设您有一个json字符串

String result = "{\"someKey\":\"someValue\"}";

创建一个：

如果您的json字符串是数组，例如：

String result = "[{\"someKey\":\"someValue\"}]"

然后您应该使用如下所示的JSONArray，而不是JSONObject

获取特定字符串的步骤

获取特定布尔值的步骤

获取特定整数的步骤

得到一个特定的长

要得到一个特定的双

要获得特定的结果，请执行以下操作：

从数组中获取项的步骤

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 一旦创建了解析器类，接下来的事情就是知道如何使用该类。下面我将解释如何使用parser类解析本例中的json

2.1。将所有这些节点名称存储在变量中：在contacts json中，我们有名称、电子邮件、地址、性别和电话号码等项。所以第一件事是将所有这些节点名存储在变量中。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。下面我创建了一个JSONParser类的实例，并使用for循环遍历每个json项，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();
}

---

您好，我已将此文件放入，但出现错误我已导入所有内容，但仍然存在问题您需要将上面的代码块包装在一个try catch中，我已编辑代码以反映这一点。如果检索到的文件包含换行符，则读取行失败。不知道Android，但在普通Java下，我使用：EDIT:在android下工作：sdk中嵌入了一个json解析器。请看下面的链接，您可以从中获得使用改装的数据。您也可以在android中使用gson：当您收到一个JSONArray时，如果您尝试使用JSONObject jObject=new JSONObject Result，您将得到一个关于解析的示例。在这种情况下，JSONArray jArray=new-JSONArrayresult将起作用

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

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

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

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

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
    }
}

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;

    }
}

// 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;

// 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();
}