我 如 何 在 Android 中 解 析 JSON ？
Android 拥有解析 json 内置所需的所有工具。 示例如下，不需要 GSON 或类似的东西。
得到 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){}}
现在有了 JSON，还是不管用
创建一个JSONObject:
JSONObject jObject = new JSONObject(result);
获取特定的字符串
String aJsonString = jObject.getString("STRINGNAME");
得到一个特定的布尔值
boolean aJsonBoolean = jObject.getBoolean("BOOLEANNAME");
得到一个特定的整数
int aJsonInteger = jObject.getInt("INTEGERNAME");
得到一个特定的长度
long aJsonLong = jObject.getLong("LONGNAME");
得到一个特定的替身
double aJsonDouble = jObject.getDouble("DOUBLENAME");
得到一个特定的 JSONArray:
JSONArray jArray = jObject.getJSONArray("ARRAYNAME");
从数组中获取
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
}}
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，下一步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 (在本例中使用)。
将所有这些节点名存储在变量中: 在联系人 json 中，我们有姓名、电子邮件、地址、性别和电话号码等项。 因此，首先要将所有这些节点名存储在变量中。 打开主活动类并将所有节点名存储在静态变量中。
// url to make requestprivate static String url = "http://api.9android.net/contacts";
// JSON Node namesprivate 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 JSONArrayJSONArray contacts = null;
使用解析器类获取 JSONObject 并遍历每个 json 项。 下面我将创建一个 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 instanceJSONParser jParser = new JSONParser();
// getting JSON string from URLJSONObject 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();}
我已经为您编写了一个简单的示例，并对源代码进行了注释。这个例子展示了如何获取 live json 并将其解析为 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();}
一旦获得了 JSONObject，请参考 SDK 以获取关于如何提取所需数据的详细信息。