如何 display/request JSON Object using Android Volley？

Question

我在 Android Studio 中遇到有关如何请求 JSON 对象的问题。

我的 Logcat 只能打印 String onResponse 但不能打印 JSONObject 值。我在 AccessActivity.java

中的 try{} 行遇到问题

我的代码解释如下。

我有这些 JSON 从 mysql 数据库中获取的对象输出。

{
    "access":"PA001",
    "password":"123",
    "fullname":"ARCADE",
    "branch":"HQ",
    "section":"MPR"
}

在我的 PHP 代码中，这是我获取数据并将其编码为 JSON 对象的方式。

access.php

<?php
    $conn = mysqli_connect("","","","");
    if(
        isset($_POST['access']) &&
        isset($_POST['password'])
    ){
        $access     = $_POST['access'];
        $password   = $_POST['password'];
        $sql = "SELECT * FROM table WHERE access = '$access' AND password = '$password' ";
        $result = mysqli_query($conn, $sql);
        if($result && mysqli_num_rows($result) > 0){
            while($row = mysqli_fetch_array($result)){

                $accessdb     = $row['access'];
                $passworddb   = $row['password'];
                $fullnamedb   = $row['fullname'];
                $branchdb     = $row['branch'];
                $sectiondb    = $row['section'];

                echo "success_access";

                $response = array('access' => $accessdb, 'password' => $passworddb, 'fullname' => $fullnamedb, 'branch' => $branchdb, 'section' => $sectiondb);
                echo json_encode($response);
            }
        mysqli_free_result($result);
        } else {
            echo "access_failed";
        }
    }
?>

但我的问题出现在 Android Studio 中，

我什至无法打印 Log.e(TAG, "JSON Object =" + jsonObject);
我无法将 JSON 对象值写入下一个 activity。

这是我的代码。

AccessActivity.java

public class AccessActivity extends AppCompatActivity{

    final String TAG = this.getClass().getName();
    EditText etAccess, etPassword;
    Button bLogin;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        etAccess        = (EditText)findViewById(R.id.etAccess);
        etPassword      = (EditText)findViewById(R.id.etPassword);
        bLogin          = (Button)findViewById(R.id.bLogin);
        bLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String url = "http://localhost/access.php";
                StringRequest stringRequest = new StringRequest(Request.Method.POST, url, new Response.Listener<String>() {
                    @Override
                    public void onResponse(String response) {
                        Log.e(TAG, "Response is = " + response);
                        if(response.equals("success_access")){
                            try {
                                JSONObject jsonObject = new JSONObject(response);
                                Log.e(TAG, "JSON Object is = " + jsonObject);

                                final String accessdb   = jsonObject.getString("access");
                                final String passworddb = jsonObject.getString("password");
                                final String fullnamedb = jsonObject.getString("fullname");
                                final String branchdb   = jsonObject.getString("branch");
                                final String sectiondb  = jsonObject.getString("branch");

                                Intent intent = new Intent(AccessActivity.this, NextActivity.class);
                                intent.putExtra("access",   accessdb);
                                intent.putExtra("password", passworddb);
                                intent.putExtra("fullname", fullnamedb);
                                intent.putExtra("branch",   branchdb);
                                intent.putExtra("section",  sectiondb);
                                AccessActivity.this.startActivity(intent);
                            } catch (JSONException e) {
                                e.printStackTrace();
                            }
                        } else{
                            Toast.makeText(getApplicationContext(), "Access Error", Toast.LENGTH_SHORT).show();
                        }
                    }
                }, new Response.ErrorListener() {
                    @Override
                    public void onErrorResponse(VolleyError error) {
                        Toast.makeText(getApplicationContext(), "Volley Error", Toast.LENGTH_SHORT).show();
                    }
                }){
                    @Override
                    protected Map<String, String> getParams() throws AuthFailureError {
                        Map<String, String> params = new HashMap<>();
                        params.put("access",   etAccess.getText().toString());
                        params.put("password", etPassword.getText().toString());
                        return params;
                    }
                };
                MySingleton.getInstance(getApplicationContext()).addToRequestQueue(stringRequest);
            }
        });
    }
}

更新：

我的 logcat 显示这个

08-22 10:22:22.059 19801-19908/com.apps.test D/NetworkSecurityConfig: No Network Security Config specified, using platform default
08-22 10:22:22.064 19801-19801/com.apps.test E/my.com.apps.test.Activity: Response is = success_access{"access":"PA001","password":"123","fullname":"ARCADE","branch":"HQ","section":"HQ"}
08-22 10:22:22.112 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)
08-22 10:22:22.128 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)
08-22 10:22:22.134 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)
08-22 10:22:22.140 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)
08-22 10:22:23.697 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)
08-22 10:22:25.751 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)
08-22 10:22:25.780 19801-19825/com.apps.test D/EGL_emulation: eglMakeCurrent: 0xb3305060: ver 2 0 (tinfo 0xb3303200)

感谢有人能帮我解决这个问题。谢谢。

Answer 1

试试这个。

在访问Activity

 Intent intent = new Intent(AccessActivity.this, NextActivity.class);
 intent.putExtra("access",   accessdb);
 intent.putExtra("password", passworddb);
 intent.putExtra("fullname", fullnamedb);
 intent.putExtra("branch",   branchdb);
 intent.putExtra("section",  sectiondb);
 AccessActivity.this.startActivity(intent);

改变

LoginActivity.this.startActivity(intent);

到

AccessActivity.this.startActivity(intent);

下一个Activity

Intent intent = getIntent();
String access = intent.getStringExtra("access");
String password = intent.getStringExtra("password");
String fullname = intent.getStringExtra("fullname");
String branch = intent.getStringExtra("branch");
String section = intent.getStringExtra("section");

已编辑

改变

if(response.equals("success_access")){
}

到

if(response.contains("success_access")){
}

并根据您的代码。您需要确保您当前的 Activity 是 com.apps.test.AccessActivity 或 com.apps.test.AccessActivity.

已编辑

改为

if (response.contains("success_access")) {
        String res = response.substring(response.indexOf("{"));
        try {
            JSONObject jsonObject = new JSONObject(res);
            final String accessdb = jsonObject.getString("access");
            final String passworddb = jsonObject.getString("password");
            final String fullnamedb = jsonObject.getString("fullname");
            final String branchdb = jsonObject.getString("branch");
            final String sectiondb = jsonObject.getString("branch");
            Log.e("Tag", accessdb);

        } catch (JSONException e) {
            e.printStackTrace();
        }
 }

Answer 2

您请求 JsonObject？您似乎对 StringRequest 有所了解，所以我会保持简单。将您的 StringRequest 更改为 JsonObjectRequest.

Answer 3

问题：

正如您在 logcat 中看到的，您从服务器获得的响应是 success_access{"access":"PA001","password":"123","fullname":"ARCADE","branch":"HQ","section":"HQ"}

首先，这不是有效的 JSON。此外，这是 response 变量的值。现在，您的 response.equals("success_access") 永远不会 return 为真，因此代码控制永远不会进入 if 块。

解法：

理想情况下，不应有像 success_access 这样的额外字符串，因为您的响应应该是一个 JSON 对象，始终包含一个指定字段（例如 result 字段）。为了显示成功，您的 JSON 将类似于：

{
    result : "success_access",
    /* other parameters down here */
}

如果失败：

{
    result : "access_failed"
}

然后您的代码应将 respose 字符串转换为 JSON（您的服务器代码应确保它 return 始终是有效的 JSON）检查result 字段的值并继续。

快速修复：

将您的代码更改为：

  ....
  Log.e(TAG, "Response is = " + response);
  String result = response.replace("{.*}","");
  String jsonString = response.replace(result, "");

  if(result.equals("success_access")){
    try {
            JSONObject jsonObject = new JSONObject(jsonString);
    ....

如何 display/request JSON Object using Android Volley？

How to display/request JSON Object using Android Volley?

php

android

json

android-volley

jsonobjectrequest