无法在 android 上使用改造显示 MySQL JSON 数据
Posted
技术标签:
【中文标题】无法在 android 上使用改造显示 MySQL JSON 数据【英文标题】：Cannot display MySQL JSON data using retrofit on android 【发布时间】：2021-04-19 04:21:39 【问题描述】：我正在尝试通过 this example 进行改造，通过 php 获取 mysql 数据。该应用程序运行良好（没有错误），但是当我尝试单击按钮时，未检索到数据。我尝试查找一些东西以确保一些东西，例如android.permission.INTERNET 和build.gradle 上的更新改造库。但它们似乎都不起作用。可以请在这里启发我...这是我到目前为止所拥有的：
ManActivity：
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
import android.widget.Button;
import android.widget.Toast;
import android.view.View;
import java.util.List;
import retrofit2.Call;
import retrofit2.Callback;
import retrofit2.Response;
import retrofit2.Retrofit;
import retrofit2.converter.gson.GsonConverterFactory;
public class MainActivity extends AppCompatActivity
TextView nametxt, agetxt, phonetxt, emailtxt;
Button retrieveBtn;
@Override
protected void onCreate(Bundle savedInstanceState)
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
nametxt = (TextView) findViewById(R.id.nametxt);
agetxt = (TextView) findViewById(R.id.agetxt);
phonetxt = (TextView) findViewById(R.id.phonetxt);
emailtxt = (TextView) findViewById(R.id.emailtxt);
retrieveBtn = (Button) findViewById(R.id.retrieveBtn);
retrieveBtn.setOnClickListener(new View.OnClickListener()
@Override
public void onClick(View v)
fetchData();
);
private void fetchData()
Retrofit retrofit = new Retrofit.Builder()
.baseUrl(Api.BASE_URL)
.addConverterFactory(GsonConverterFactory.create())
.build();
Api api = retrofit.create(Api.class);
Call<List<Details_Pojo>> call = api.getstatus();
call.enqueue(new Callback<List<Details_Pojo>>()
@Override
public void onResponse(Call<List<Details_Pojo>> call, Response<List<Details_Pojo>> response)
List<Details_Pojo> adslist = response.body();
String name = adslist.get(0).getName();
String age = adslist.get(0).getAge();
String phone = adslist.get(0).getPhone();
String email = adslist.get(0).getEmail();
nametxt.setText(name);
agetxt.setText(age);
phonetxt.setText(phone);
emailtxt.setText(email);
@Override
public void onFailure(Call<List<Details_Pojo>> call, Throwable t)
Toast.makeText(MainActivity.this, ""+t.getMessage().toString(), Toast.LENGTH_SHORT).show();
);
Details_Pojo：
import com.google.gson.annotations.Expose;
import com.google.gson.annotations.SerializedName;
public class Details_Pojo
@SerializedName("Name")
@Expose
private String Name;
@SerializedName("Age")
@Expose
private String Age;
@SerializedName("Phone")
@Expose
private String Phone;
@SerializedName("Email")
@Expose
private String Email;
public String getName()
return Name;
public void setName(String name)
Name = name;
public String getAge()
return Age;
public void setAge(String age)
Age = age;
public String getPhone()
return Phone;
public void setPhone(String phone)
Phone = phone;
public String getEmail()
return Email;
public void setEmail(String email)
Email = email;
API：
import retrofit2.Call;
import retrofit2.http.GET;
import java.util.List;
public interface Api
String BASE_URL = "http://127.0.0.1/~xxxx/"; //xxxx is the user name and the php works
@GET("Apppi.php")
Call<List<Details_Pojo>> getstatus();
JSON：
["name":"Peter","age":"10","phone":"2345343","email":"1232e@yahoo.com"]
activity_main.xml：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_
android:layout_
android:orientation="vertical"
android:padding="100dp"
tools:context=".MainActivity">
<TextView
android:id="@+id/nametxt"
android:layout_
android:layout_
android:textSize="20dp"
android:hint="Name"/>
<TextView
android:id="@+id/agetxt"
android:layout_
android:layout_
android:textSize="20dp"
android:hint="Age"/>
<TextView
android:id="@+id/phonetxt"
android:layout_
android:layout_
android:textSize="20dp"
android:hint="Phone"/>
<TextView
android:id="@+id/emailtxt"
android:layout_
android:layout_
android:textSize="20dp"
android:hint="Email"/>
<Button
android:id="@+id/retrieveBtn"
android:layout_
android:layout_
android:layout_marginTop="40dp"
android:text="Retrieve Data"/>
</LinearLayout>
Build.gradle：
dependencies
implementation 'androidx.appcompat:appcompat:1.2.0'
implementation 'com.google.android.material:material:1.2.1'
implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
testImplementation 'junit:junit:4.+'
androidTestImplementation 'androidx.test.ext:junit:1.1.2'
androidTestImplementation 'androidx.test.espresso:espresso-core:3.3.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.google.code.gson:gson:2.8.5'
这就是我在 Logcat 上看到的，在网上搜索后，retrofit2.9.0 似乎出现了警告......
2021-01-13 22:46:26.657 3193-3193/com.example.fetching3 I/ample.fetching: Not late-enabling -Xcheck:jni (already on)
2021-01-13 22:46:26.711 3193-3193/com.example.fetching3 I/ample.fetching: Unquickening 12 vdex files!
2021-01-13 22:46:26.715 3193-3193/com.example.fetching3 W/ample.fetching: Unexpected CPU variant for X86 using defaults: x86
2021-01-13 22:46:28.176 3193-3193/com.example.fetching3 D/NetworkSecurityConfig: No Network Security Config specified, using platform default
2021-01-13 22:46:28.177 3193-3193/com.example.fetching3 D/NetworkSecurityConfig: No Network Security Config specified, using platform default
2021-01-13 22:46:28.317 3193-3238/com.example.fetching3 D/libEGL: loaded /vendor/lib/egl/libEGL_emulation.so
2021-01-13 22:46:28.320 3193-3238/com.example.fetching3 D/libEGL: loaded /vendor/lib/egl/libGLESv1_CM_emulation.so
2021-01-13 22:46:28.327 3193-3238/com.example.fetching3 D/libEGL: loaded /vendor/lib/egl/libGLESv2_emulation.so
2021-01-13 22:46:28.488 3193-3193/com.example.fetching3 W/ample.fetching: Accessing hidden method Landroid/view/View;->computeFitSystemWindows(Landroid/graphics/Rect;Landroid/graphics/Rect;)Z (greylist, reflection, allowed)
2021-01-13 22:46:28.488 3193-3193/com.example.fetching3 W/ample.fetching: Accessing hidden method Landroid/view/ViewGroup;->makeOptionalFitsSystemWindows()V (greylist, reflection, allowed)
2021-01-13 22:46:28.786 3193-3234/com.example.fetching3 D/HostConnection: HostConnection::get() New Host Connection established 0xecf1ee00, tid 3234
2021-01-13 22:46:28.810 3193-3234/com.example.fetching3 D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_3_0
2021-01-13 22:46:28.823 3193-3234/com.example.fetching3 W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
2021-01-13 22:46:28.829 3193-3234/com.example.fetching3 D/EGL_emulation: eglCreateContext: 0xecf1ecb0: maj 3 min 0 rcv 3
2021-01-13 22:46:28.852 3193-3234/com.example.fetching3 D/EGL_emulation: eglMakeCurrent: 0xecf1ecb0: ver 3 0 (tinfo 0xed270a10) (first time)
2021-01-13 22:46:28.908 3193-3234/com.example.fetching3 I/Gralloc4: mapper 4.x is not supported
2021-01-13 22:46:28.909 3193-3234/com.example.fetching3 D/HostConnection: createUnique: call
2021-01-13 22:46:28.909 3193-3234/com.example.fetching3 D/HostConnection: HostConnection::get() New Host Connection established 0xecf1fc70, tid 3234
2021-01-13 22:46:28.963 3193-3234/com.example.fetching3 D/goldfish-address-space: allocate: Ask for block of size 0x100
2021-01-13 22:46:28.963 3193-3234/com.example.fetching3 D/goldfish-address-space: allocate: ioctl allocate returned offset 0x3fe663000 size 0x2000
2021-01-13 22:46:28.984 3193-3234/com.example.fetching3 D/HostConnection: HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_host_side_tracing ANDROID_EMU_gles_max_version_3_0
2021-01-13 22:46:29.286 3193-3193/com.example.fetching3 I/Choreographer: Skipped 34 frames! The application may be doing too much work on its main thread.
2021-01-13 22:46:45.706 3193-3193/com.example.fetching3 W/ample.fetching: Accessing hidden method Ljava/lang/invoke/MethodHandles$Lookup;-><init>(Ljava/lang/Class;I)V (greylist, reflection, allowed)
2021-01-13 22:46:45.931 3193-3193/com.example.fetching3 W/ample.fetching: Accessing hidden method Ldalvik/system/CloseGuard;->get()Ldalvik/system/CloseGuard; (greylist,core-platform-api, reflection, allowed)
2021-01-13 22:46:45.932 3193-3193/com.example.fetching3 W/ample.fetching: Accessing hidden method Ldalvik/system/CloseGuard;->open(Ljava/lang/String;)V (greylist,core-platform-api, reflection, allowed)
2021-01-13 22:46:45.932 3193-3193/com.example.fetching3 W/ample.fetching: Accessing hidden method Ldalvik/system/CloseGuard;->warnIfOpen()V (greylist,core-platform-api, reflection, allowed)
2021-01-13 22:46:46.076 3193-3193/com.example.fetching3 D/CompatibilityChangeReporter: Compat change id reported: 147798919; UID 10158; state: ENABLED
【问题讨论】：
【参考方案1】：将SerializedName注解的值改为Json中对应的key
试试下面的，
public class Details_Pojo
@SerializedName("name")
@Expose
private String Name;
@SerializedName("age")
@Expose
private String Age;
@SerializedName("phone")
@Expose
private String Phone;
@SerializedName("email")
@Expose
private String Email;
//rest of the logic remains the same
编辑：
从getstatus返回Array而不是List，并在任何地方使用适当的方法
public interface Api
String BASE_URL = "http://127.0.0.1/~xxxx/"; //xxxx is the user name and the php works
@GET("Apppi.php")
Call<Array<Details_Pojo>> getstatus();
【讨论】：
好收获！我已经更改了大写以匹配它，但目前它仍然没有显示来自 MySQL 的 JSON 数据....（应用程序正在运行，但单击按钮时没有显示数据..） 现在检查答案，看看是否能解决错误 感谢您的建议。我试图用import java.sql.Array; 实现Call<Array<Details_Pojo>> getstatus(); 但它带有错误Type 'java.sql.Array' does not have type parameters？我不能在这里使用数组...嗯
使用标准库，'java.utils.Array`
你也可以看看这个链接吗：***.com/questions/65912445/…【参考方案2】：
根据日志，这可能是由于 http 而不是 https。
我们有两种选择，要么使用network_configs 排除这些，要么在Manifest 中启用明文流量。
还要将 POJO 对象保留为 @rcs 提及的所有小写字符。
尝试在下面使用，让我知道会发生什么，也请在成功和失败案例中记录数据，看看发生了什么
android:usesCleartextTraffic="true"
【讨论】：
以上是关于无法在 android 上使用改造显示 MySQL JSON 数据的主要内容，如果未能解决你的问题，请参考以下文章
android-jetifier: "无法解析所有工件";新项目上的“改造工件失败”
Android - 使用改造时出现错误“无法构造实例（尽管至少存在一个创建）”