本文介绍了类型为java.lang.String的！DOCTYPE无法转换为JSONObject的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在使用Android Studio创建一个用户登录和注册应用程序，但是我是一个初学者，并且获得了JSONException.
I'm creating a user login and registration application with Android Studio but I'm a beginner and getting a JSONException.
我使用了此教程来整理我的代码.
I used this tutorial to put together my code.
以下是错误信息:
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ org.json.JSONException: Value <!DOCTYPE of type java.lang.String cannot be converted to JSONObject
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at org.json.JSON.typeMismatch(JSON.java:111)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at org.json.JSONObject.<init>(JSONObject.java:159)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at org.json.JSONObject.<init>(JSONObject.java:172)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.example.dev5.registration.app.RegisterActivity$3.onResponse(RegisterActivity.java:119)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.example.dev5.registration.app.RegisterActivity$3.onResponse(RegisterActivity.java:110)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:60)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.volley.toolbox.StringRequest.deliverResponse(StringRequest.java:30)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.volley.ExecutorDelivery$ResponseDeliveryRunnable.run(ExecutorDelivery.java:99)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.os.Handler.handleCallback(Handler.java:733)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.os.Handler.dispatchMessage(Handler.java:95)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.os.Looper.loop(Looper.java:136)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at android.app.ActivityThread.main(ActivityThread.java:5001)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at java.lang.reflect.Method.invokeNative(Native Method)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at java.lang.reflect.Method.invoke(Method.java:515)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
06-12 05:17:31.052 8831-8831/com.example.dev5.registration W/System.err﹕ at dalvik.system.NativeStart.main(Native Method)
这是我的代码:
package com.example.dev5.registration.app;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import com.android.volley.Request.Method;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.example.dev5.registration.app.helper.SQLiteHandler;
import com.example.dev5.registration.app.helper.SessionManager;
import org.json.JSONException;
import org.json.JSONObject;
import java.util.HashMap;
import java.util.Map;
public class RegisterActivity extends Activity {
private static final String TAG = RegisterActivity.class.getSimpleName();
private Button btnRegister;
private Button btnLinkToLogin;
private EditText inputFullName;
private EditText inputEmail;
private EditText inputPassword;
private ProgressDialog pDialog;
private SessionManager session;
private SQLiteHandler db;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
inputFullName = (EditText) findViewById(R.id.name);
inputEmail = (EditText) findViewById(R.id.email);
inputPassword = (EditText) findViewById(R.id.password);
btnRegister = (Button) findViewById(R.id.btnRegister);
btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen);
// Progress dialog
pDialog = new ProgressDialog(this);
pDialog.setCancelable(false);
// Session manager
session = new SessionManager(getApplicationContext());
// SQLite database handler
db = new SQLiteHandler(getApplicationContext());
// Check if user is already logged in or not
if (session.isLoggedIn()) {
// User is already logged in. Take him to main activity
Intent intent = new Intent(RegisterActivity.this,
MainActivity.class);
startActivity(intent);
finish();
}
// Register Button Click event
btnRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String name = inputFullName.getText().toString();
String email = inputEmail.getText().toString();
String password = inputPassword.getText().toString();
if (!name.isEmpty() && !email.isEmpty() && !password.isEmpty()) {
registerUser(name, email, password);
} else {
Toast.makeText(getApplicationContext(),
"Please enter your details!", Toast.LENGTH_LONG)
.show();
}
}
});
// Link to Login Screen
btnLinkToLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
LoginActivity.class);
startActivity(i);
finish();
}
});
}
/**
* Function to store user in MySQL database will post params(tag, name,
* email, password) to register url
* */
private void registerUser(final String name, final String email,
final String password) {
// Tag used to cancel the request
String tag_string_req = "req_register";
pDialog.setMessage("Registering ...");
showDialog();
StringRequest strReq = new StringRequest(Method.POST,
AppConfig.URL_REGISTER, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Log.d(TAG, "Register Response: " + response);
hideDialog();
try {
JSONObject jObj = new JSONObject(response);
boolean error = jObj.getBoolean("error");
if (!error) {
// User successfully stored in MySQL
// Now store the user in sqlite
String uid = jObj.getString("uid");
JSONObject user = jObj.getJSONObject("user");
String name = user.getString("name");
String email = user.getString("email");
String created_at = user
.getString("created_at");
// Inserting row in users table
db.addUser(name, email, uid, created_at);
// Launch login activity
Intent intent = new Intent(
RegisterActivity.this,
LoginActivity.class);
startActivity(intent);
finish();
} else {
// Error occurred in registration. Get the error
// message
String errorMsg = jObj.getString("error_msg");
Toast.makeText(getApplicationContext(),
errorMsg, Toast.LENGTH_LONG).show();
}
} catch (JSONException e) {
e.printStackTrace();
}
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e(TAG, "Registration Error: " + error.getMessage());
Toast.makeText(getApplicationContext(),
error.getMessage(), Toast.LENGTH_LONG).show();
hideDialog();
}
}) {
@Override
protected Map<String, String> getParams() {
// Posting params to register url
Map<String, String> params = new HashMap<String, String>();
params.put("tag", "register");
params.put("name", name);
params.put("email", email);
params.put("password", password);
return params;
}
};
// Adding request to request queue
AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
}
private void showDialog() {
if (!pDialog.isShowing())
pDialog.show();
}
private void hideDialog() {
if (pDialog.isShowing())
pDialog.dismiss();
}
}
有人可以帮忙解释一下吗?
Can anyone help explain it?
推荐答案
"<!DOCTYPE of type java.lang.String cannot be converted to JSONObject"
发生此错误有多种原因.一个例子在这里. 如果假设服务器返回错误页面未找到-404.则存在一个HTML页面.因此您的json无法解析它.
This error happens for multiple reasons. One example is here. If suppose the server returns the error Page not found - 404. Then there is a HTML page. So your json not able to parse it.
解决方案是您需要检查服务器的响应返回.
The solution is you need to check your response returns from the server.
在解析json之前，您需要检查您的响应，有一个名为邮递员尝试一下.
You need to check your response before you parse your json there is one tool called POSTMAN try this.
这篇关于类型为java.lang.String的！DOCTYPE无法转换为JSONObject的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！