java - 如何修复 org.json.JSONException : on Volley?

Question

我正在通过与 php(网络)连接在 android 上开发登录。

代码

package com.example.salmakhalil.myapplication;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.android.volley.AuthFailureError;
import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.HashMap;
import java.util.Map;

public class LoginActivity extends AppCompatActivity {
    private EditText email,password;
    private Button btn_login;
    private TextView link_regist;
    private ProgressBar loading;
    private static String URL_LOGIN="http://192.168.8.101/android_register_login/login.php";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        loading=findViewById(R.id.loading);
        email=findViewById(R.id.email);
        password=findViewById(R.id.password);
        btn_login=findViewById(R.id.btn_login);
        link_regist=findViewById(R.id.link_regist);

        btn_login.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String mEmail=email.getText().toString().trim();
                String mPass=password.getText().toString().trim();
                if (!mEmail.isEmpty() || !mPass.isEmpty()){
                    Login(mEmail,mPass);
                }
                else {
                    email.setError("Please insert email");
                    password.setError("Please insert Password");
                }
            }
        });

        link_regist.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startActivity(new Intent(LoginActivity.this, MainActivity.class));
            }
        });
    }

    private void Login(String email, String password){
        loading.setVisibility(View.VISIBLE);
        btn_login.setVisibility(View.GONE);

//我认为这里面临一个问题

        StringRequest stringRequest=new StringRequest(Request.Method.POST, URL_LOGIN,
                new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        try {
                            JSONObject jsonObject=new JSONObject(response);
                            String success = jsonObject.getString("success");
                            JSONArray jsonArray=jsonObject.getJSONArray("login");


                            if (success.equals("1")) {
                               for (int i=0; i<jsonArray.length();i++){
                                   JSONObject object = jsonArray.getJSONObject(i);

                                   String name = object.getString("name").trim();
                                   String email=object.getString( "email").trim();
                                   Toast.makeText(LoginActivity.this,
                                           "Success Login. \nYour Name : "
                                                   +name+"\nYour Email : "
                                                   +email, Toast.LENGTH_SHORT)
                                           .show();
                                   loading.setVisibility(View.GONE);
                               }

                            }

                        } catch (JSONException e) {
                            e.printStackTrace();
                            loading.setVisibility(View.GONE);
                            btn_login.setVisibility(View.VISIBLE);
                            Toast.makeText(LoginActivity.this, "Error!!! " +e.toString(),
                                    Toast.LENGTH_SHORT).show();
                        }

                    }
                },
                new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(LoginActivity.this, "Error!! " +error.toString(),
                                Toast.LENGTH_SHORT).show();
                    }
                })
        {
            @Override
            protected Map<String, String> getParams() throws AuthFailureError {
                Map<String, String> params = new HashMap<>();
                params.put("email", email);
                params.put("password", password);
                return params;
            }
        };
        RequestQueue requestQueue = Volley.newRequestQueue(this);
        requestQueue.add(stringRequest);


    }
}

当我点击登录按钮时，它显示错误

org.json.JSONException: No value for success.

我一整天都在努力修复它。我读过 Stack 上的其他帖子，但没有人帮助我。我希望你可以帮助我。谢谢。

Answer 1

显然，您在 onResponse() 中收到的 jsonObject 没有条目值“成功”

您应该使用方法 jsonObject.optString("success"); 而不是 jsonObject.getString("success");

如果键 “success”不存在，

optString("success") 返回空字符串 ("")。另一方面，getString("success") 会抛出 JSONException。