php - Recycler View无法显示mysql数据
问题描述
请帮我处理这段代码。我想显示来自mysql的数据并将其显示到android。我在我的 mysql 中插入数据并在我的 android 上显示我的 mysql 中有多少数据，以便我知道我的 android 应用程序是否可以从 mysql 读取我的所有数据，但是当我运行我的 android 应用程序时，它说没有数据。请帮我
安卓代码...
data_list = new ArrayList<>();
load_data_from_server();
gridLayoutManager = new GridLayoutManager(this, 2);
recyclerView.setLayoutManager(gridLayoutManager);
adapter = new CustomAdapter(this, data_list);
recyclerView.setAdapter(adapter);
if (adapter.getItemCount() == 0){
Toast.makeText(this, "Empty", Toast.LENGTH_SHORT).show();
}
private void load_data_from_server() {
AsyncTask<Integer, Void, Void> task = new AsyncTask<Integer, Void, Void>() {
@Override
protected Void doInBackground(Integer... integers) {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("http://192.168.43.147/webapp/travelplanning.php")
.build();
try {
Response response = client.newCall(request).execute();
JSONArray array = new JSONArray(response.body().string());
for(int i = 0; i < array.length(); i++){
JSONObject object = array.getJSONObject(i);
MyData data = new MyData(object.getInt("ID"), object.getString("AttractionName"), object.getString("Location"));
data_list.add(data);
}
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
adapter.notifyDataSetChanged();
}
};
}
适配器...
public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {
private Context context;
private List<MyData> my_data;
public CustomAdapter(Context context, List<MyData> my_data) {
this.context = context;
this.my_data = my_data;
}
@NonNull
@Override
public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.travel_planning_card, parent, false);
return new ViewHolder(itemView);
}
@Override
public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
holder.id.setText(my_data.get(position).getId());
holder.attractionName.setText(my_data.get(position).getAttractioName());
holder.location.setText(my_data.get(position).getLocation());
}
@Override
public int getItemCount() {
return my_data.size();
}
public class ViewHolder extends RecyclerView.ViewHolder {
public TextView attractionName, location, id;
public ImageView image;
public ViewHolder(@NonNull View itemView) {
super(itemView);
attractionName = itemView.findViewById(R.id.tvAttractionName);
location = itemView.findViewById(R.id.tvLocation);
id = itemView.findViewById(R.id.tvID);
}
}
}
构造函数...
package com.example.tourismolocal;
public class MyData {
private int id;
private String attractioName, location, image;
public MyData(int id, String attractioName, String location) {
this.id = id;
this.attractioName = attractioName;
this.location = location;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getAttractioName() {
return attractioName;
}
public void setAttractioName(String attractioName) {
this.attractioName = attractioName;
}
public String getLocation() {
return location;
}
public void setLocation(String location) {
this.location = location;
}
}
布局...
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
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_width="match_parent"
android:layout_height="match_parent"
tools:context=".travelplanning"
android:background="@drawable/img_banner">
<FrameLayout
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="10dp"
android:layout_marginTop="120dp"
android:layout_marginEnd="10dp"
android:layout_marginBottom="60dp"
android:background="@drawable/square"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/recTravel">
</androidx.recyclerview.widget.RecyclerView>
</LinearLayout>
</FrameLayout>
<EditText
android:id="@+id/etSearchAttraction"
android:layout_width="0dp"
android:layout_height="38dp"
android:layout_marginStart="10dp"
android:layout_marginTop="72dp"
android:autofillHints=""
android:background="@drawable/searchdestination"
android:drawableStart="@drawable/icon_search1"
android:ems="10"
android:hint="@string/etsearchdestination"
android:inputType="textPersonName"
android:paddingStart="10dp"
app:layout_constraintEnd_toStartOf="@+id/btnAddAttraction"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
android:focusable="false"/>
<Button
android:id="@+id/btnAddAttraction"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_marginStart="5dp"
android:layout_marginEnd="10dp"
android:background="@drawable/icon_plus"
app:layout_constraintBaseline_toBaselineOf="@+id/etSearchAttraction"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.5"
app:layout_constraintStart_toEndOf="@+id/etSearchAttraction" />
<FrameLayout
android:id="@+id/frameLayout2"
android:layout_width="match_parent"
android:layout_height="50dp"
android:background="@drawable/navbar"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="1dp"
android:background="@drawable/nav_topborder"></LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="63dp"
android:orientation="horizontal"
android:paddingTop="1dp">
<Button
android:id="@+id/btnAttraction"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="@drawable/navbar"
android:drawableTop="@drawable/icon_places"
android:paddingTop="7dp"
android:paddingBottom="18dp"
android:text="@string/attract"
android:textAllCaps="false"
android:textColor="#2d3e52"
android:textSize="9dp" />
<Button
android:id="@+id/btnTrips"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="@drawable/navbar"
android:drawableTop="@drawable/icon_trips"
android:paddingTop="7dp"
android:paddingBottom="18dp"
android:text="@string/trips"
android:textAllCaps="false"
android:textColor="#A6A3A3"
android:textSize="9dp" />
<Button
android:id="@+id/btnWishlist"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_weight="1"
android:background="@drawable/navbar"
android:drawableTop="@drawable/icon_wishlist"
android:paddingTop="7dp"
android:paddingBottom="18dp"
android:text="@string/wishlist"
android:textAllCaps="false"
android:textColor="#A6A3A3"
android:textSize="9dp" />
</LinearLayout>
</FrameLayout>
<ImageView
android:id="@+id/imgUser"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_marginStart="10dp"
android:layout_marginTop="15dp"
android:src="@drawable/icon_mainuser"
app:layout_constraintStart_toEndOf="@+id/imageView4"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<ImageView
android:id="@+id/imageView6"
android:layout_width="0dp"
android:layout_height="25dp"
android:layout_marginTop="20dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="@drawable/img_logowhite" />
卡片布局...
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_height="wrap_content"
android:layout_width="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.cardview.widget.CardView
android:layout_width="match_parent"
android:layout_height="400dp"
android:orientation="vertical">
<ImageView
android:id="@+id/imgAttraction"
android:layout_width="match_parent"
android:layout_height="300dp"
android:scaleType="centerCrop"
android:src="@mipmap/ic_launcher_round"
android:layout_margin="10dp"/>
<LinearLayout
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_marginTop="320dp"
android:layout_width="match_parent"
android:layout_height="55dp"
android:orientation="horizontal">
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/tvAttractionName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Attraction Name"
android:textSize="20dp"
android:textColor="#000000"/>
<TextView
android:id="@+id/tvLocation"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Location"
android:textSize="20dp"
android:textColor="#000000"/>
</LinearLayout>
<TextView
android:id="@+id/tvID"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ID"
android:textSize="26dp"
android:textColor="#000000"
android:layout_marginTop="7dp"
android:textAlignment="textEnd"
android:visibility="invisible"/>
<TextView
android:id="@+id/tvRate"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="7dp"
android:text="Rating"
android:textAlignment="textEnd"
android:textColor="#000000"
android:textSize="26dp" />
</LinearLayout>
</androidx.cardview.widget.CardView>
PHP 文件....
<?php
require "init.php";
if(mysqli_connect_error($con))
{
echo "Failed to connect";
}
$query = "Select id, attractionname, location from attraction";
$result = mysqli_query($con, $query);
if($result){
while($row=mysqli_fetch_array($result)){
$flag[]=$row;
}
print(json_encode($flag));
}
mysqli_close($con);
?>
解决方案
你不能这样。因为，您不会更改 AsyncTask 中的 ui 操作。尝试这个。
private void load_data_from_server() {
AsyncTask<Integer, Void, Void> task = new AsyncTask<Integer, Void, Void>() {
@Override
protected Void doInBackground(Integer... integers) {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder()
.url("http://192.168.43.147/webapp/travelplanning.php")
.build();
try {
Response response = client.newCall(request).execute();
JSONArray array = new JSONArray(response.body().string());
List<MyData> list = new ArrayList<>();
for(int i = 0; i < array.length(); i++){
JSONObject object = array.getJSONObject(i);
MyData data = new MyData(object.getInt("ID"), object.getString("AttractionName"), object.getString("Location"));
list.add(data);
}
setListData(list);
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
}
};
}
private void setListData(List<MyData> list) {
data_list.addAll(list);
adapter.notifyDataSetChanged();
}
推荐阅读
- python - RandomForest 高 OOB 分数与低 KFold 验证分数
- java - PrintWriter 创建空文件
- r - 将特定列中的 NA 值转换为 R 中的“”字段
- flutter - 尝试在小部件中显示列表项时遇到空值
- javascript - 如何在 tolocalestring() 中指定分隔符
- php - Laravel 检索董事会的所有父母
- woocommerce - 找不到单一产品 Woocommerce 模板丢失
- python - Python继承结构和参数
- java - 错误：没有这样的文件或目录试图从终端创建 jar 文件
- django - 通过虚拟环境运行时出现 Django 错误：线程 django-main-thread 中的异常：