我是 android 的新手。我想在用户登录时使用 Mysql 获取用户信息。但是当我在登录后进行第二个 Activity 时，我得到的是空白页面。我已经使用 NameValuePair 将值传递给php 变量。
public class Messages extends BaseActivity {
private String[] navMenuTitles;
private TypedArray navMenuIcons;
private EditText editTextName;
SharedPreferences sp;
private String jsonResult;
private ListView listView;
private Button b;
EditText etname, et;
TextView tv;
String myJSON;
private static final String TAG_RESULTS="result";
private static final String TAG_NAME = "message_recd";
private static final String TAG_ADD ="message_sent";
JSONArray peoples = null;
ArrayList<HashMap<String, String>> personList;
ListView list;
public static final String USER_NAME = "USERNAME";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
Intent intent = getIntent();
String fName = intent.getStringExtra("fname");
TextView textView = (TextView) findViewById(R.id.fname);
textView.setText("Welcome "+fName);
navMenuTitles = getResources().getStringArray(R.array.nav_drawer_items);
navMenuIcons = getResources().obtainTypedArray(R.array.nav_drawer_icons);
// load icons from
// strings.xml
set(navMenuTitles, navMenuIcons);
editTextName = (EditText) findViewById(R.id.editTextName);
b=(Button)findViewById(R.id.button1);
list = (ListView) findViewById(R.id.listView);
personList = new ArrayList<HashMap<String,String>>();
getData();
}
protected void showList(){
try {
JSONArray peoples = new JSONArray(myJSON);
for(int i=0;i<peoples.length();i++){
JSONObject c = peoples.getJSONObject(i);
String name=null, address=null;
if(c.has("message_recd"))
name = c.getString("message_recd");
else if(c.has("message_sent"))
address = c.getString("message_sent");
HashMap<String,String> persons = new HashMap<String,String>();
persons.put(TAG_NAME,name);
persons.put(TAG_ADD,address);
personList.add(persons);
}
ListAdapter adapter = new SimpleAdapter(
Messages.this, personList, R.layout.list_item,
new String[]{TAG_NAME,TAG_ADD},
new int[]{R.id.name, R.id.address}
);
list.setAdapter(adapter);
} catch (JSONException e) {
e.printStackTrace();
}
}
public void getData(){
class GetDataJSON extends AsyncTask<String, Void, String>{
@Override
protected String doInBackground(String... params) {
DefaultHttpClient httpclient = new DefaultHttpClient(new BasicHttpParams());
HttpPost httppost = new HttpPost("http://10.0.2.2/progress_card/testing.php");
httppost.setHeader("Content-type", "application/json");
InputStream inputStream = null;
String result = null;
try {
Intent intent1 = getIntent();
String fName = intent1.getStringExtra("fname");
List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair("username", fName));
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
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){}
}
return result;
}
@Override
protected void onPostExecute(String result){
myJSON=result;
showList();
}
}
GetDataJSON g = new GetDataJSON();
g.execute();
}
}
我的日志
09-23 01:57:45.436: W/System.err(1670): org.json.JSONException: Value <br of type java.lang.String cannot be converted to JSONArray
09-23 01:57:45.456: W/System.err(1670): at org.json.JSON.typeMismatch(JSON.java:111)
09-23 01:57:45.456: W/System.err(1670): at org.json.JSONArray.<init>(JSONArray.java:96)
09-23 01:57:45.476: W/System.err(1670): at org.json.JSONArray.<init>(JSONArray.java:108)
09-23 01:57:45.476: W/System.err(1670): at com.pitechnologies.progresscard.Messages.showList(Messages.java:107)
09-23 01:57:45.476: W/System.err(1670): at com.pitechnologies.progresscard.Messages$1GetDataJSON.onPostExecute(Messages.java:180)
09-23 01:57:45.486: W/System.err(1670): at com.pitechnologies.progresscard.Messages$1GetDataJSON.onPostExecute(Messages.java:1)
09-23 01:57:45.486: W/System.err(1670): at android.os.AsyncTask.finish(AsyncTask.java:632)
09-23 01:57:45.486: W/System.err(1670): at android.os.AsyncTask.access$600(AsyncTask.java:177)
09-23 01:57:45.496: W/System.err(1670): at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:645)
09-23 01:57:45.506: W/System.err(1670): at android.os.Handler.dispatchMessage(Handler.java:102)
09-23 01:57:45.506: W/System.err(1670): at android.os.Looper.loop(Looper.java:136)
09-23 01:57:45.516: W/System.err(1670): at android.app.ActivityThread.main(ActivityThread.java:5001)
09-23 01:57:45.516: W/System.err(1670): at java.lang.reflect.Method.invokeNative(Native Method)
09-23 01:57:45.516: W/System.err(1670): at java.lang.reflect.Method.invoke(Method.java:515)
09-23 01:57:45.516: W/System.err(1670): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
09-23 01:57:45.516: W/System.err(1670): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
09-23 01:57:45.536: W/System.err(1670): at dalvik.system.NativeStart.main(Native Method)
我的PHP代码
<?php
include "check.php";
define('HOST','localhost');
define('USER','root');
define('PASS','');
define('DB','progress_card');
$con = mysqli_connect(HOST,USER,PASS,DB);
$sql1 = "select * from student_detail where parentusername='".$username."'";
$res1 = mysqli_query($con,$sql1);
$row1=mysqli_fetch_array($res1);
$cl=$row1['class']."-".$row1['section'];
$sql2="select * from teachers where classassign='$cl'";
$res2 = mysqli_query($con,$sql2);
$row2=mysqli_fetch_array($res2);
$to=$row2['email'];
$from=$row1['parentemail'];
$result = array();
$sql = "select * from messages where to_email='".$to."' and from_email='".$from."'";
$res = mysqli_query($con,$sql);
while($row = mysqli_fetch_array($res))
{
array_push($result,array('message_recd'=>$row['message']));
}
$sqlw = "select * from messages where from_email='".$to."' and to_email='".$from."'";
$resw = mysqli_query($con,$sqlw);
while($row5 = mysqli_fetch_array($resw))
{
array_push($result,array('message_sent'=>$row5['message']));
}
//array_push($result,array('message_sent'=>"dfdsghdfgddfgdsd"));
//array_push($result,array('message_sent'=>"sfdsflkufhskfhdskjfsfssadfadsffsafasfsfsadfafsaf"));
//array_push($result,array('message_recd'=>$row1['parentemail'],'message_sent'=>$row2['email']));
echo json_encode($result);
mysqli_close($con);
?>
我的 php 响应
[{"message_recd":"asdadasda"},{"message_recd":"hello"},{"message_recd":"how r u"},{"message_recd":"hello\n"},{"message_recd":"hello"},{"message_recd":"1"},{"message_recd":"qd"},{"message_recd":"1"},{"message_recd":"hello12"},{"message_recd":"hello again"},{"message_recd":"hey whtas up"},{"message_recd":"jhkwdfjdw"},{"message_recd":"is it working"},{"message_recd":"qw"},{"message_recd":"sdfsdfsdfsadf"},{"message_recd":"qwertyuiop"},{"message_recd":"aaaa"},{"message_sent":"hey whtas up"}]
最佳答案
没有看到你的响应结构，我可以假设你从你的 PHP 页面返回这样的东西:
{
"test": [
{
"data": "myData"
}
]
}
这意味着您在 JSONObject 中有一个 JSONArray。
尝试更改此行 JSONArray peoples = new JSONArray(myJSON);像这样JSONObject people = new JSONObject(myJSON);然后你可以做这样的事情JSONArray peopleArray = people.getJSONArray("arrayKey");
希望这对您有所帮助!
编辑:
刚刚看到您编辑的问题(带有响应)，这是一个有效的 JSONArray，因此您在阅读响应时可能做错了什么。
更改此行 sb.append(line + "\n");对此 sb.append(line);然后再试一次。另请查看您的 StringBuilder完成获取数据后包含好的数据!
编辑 2:
此外，您确定您的 API 调用正确返回数据(没有给您错误)，因为在异常中它说 org.json.JSONException: Value <br of type java.lang.String cannot be converted to JSONArray ，意思是你的 StringBuilder字符串以 html <br> 开头标签。
关于android - 如何在用户登录时获取 json 中的用户数据？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32732100/