Android中使用RequestQueue佇列訪問web服務器和Listview自定義配接器制作智慧醫療界面

首先我們先來了解本次我們需要做的效果，

使用RequestQueue訪問醫院資訊服務器，并將服務器內的json資料獲取出來添加到對應的位置，

介面：http://smartcity.leeda.top/interface/SCHospital/getAll?userId=NzA2

答題步驟：

新建一個MainActivity2

對應的xml檔案中按照上圖布局好

activity_main2.xml對應代碼

<?xml version="1.0" encoding="utf-8"?>
<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_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".ProgectOne.MainActivity2">

    <TextView
        android:id="@+id/textView11"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:textSize="28dp"
        android:text="選擇醫院" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/textView"
            android:layout_width="100dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:text="名稱" />

        <TextView
            android:id="@+id/textView2"
            android:layout_width="80dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:text="等級" />

        <TextView
            android:id="@+id/textView4"
            android:layout_width="50dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:text="地區" />

        <TextView
            android:id="@+id/textView9"
            android:layout_width="60dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:gravity="center"
            android:text="操作" />
    </LinearLayout>

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_gravity="center"
        android:id="@+id/listview2"/>

</LinearLayout>

為listview添加一個自定義的子布局xml檔案

layout_main2_item.xml檔案代碼

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/name2"
        android:layout_width="100dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:text="名稱" />

    <TextView
        android:id="@+id/grade2"
        android:layout_width="80dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:text="等級" />

    <TextView
        android:id="@+id/area2"
        android:layout_width="50dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:text="地區" />

    <Button
        android:id="@+id/button"
        android:layout_width="60dp"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:gravity="center"
        android:text="進入查看" />
</LinearLayout>

相應的布局就已經完成了，接下來將進入java代碼的撰寫

我們打開介面，可以看到醫院資訊，根據醫院資訊我門新建一個Java檔案用來封裝醫院資訊，命名為HospitalClass

package com.example.myapplication.ProgectOne;

import java.io.Serializable;

public class HospitalClass implements Serializable {
    private String name;//醫院名稱
    private int grade;//醫院等級
    private String area;//醫院地區
    private int id;//醫院id

    public String getName() {
        return name;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getGrade() {
        return grade;
    }

    public void setGrade(int grade) {
        this.grade = grade;
    }

    public String getArea() {
        return area;
    }

    public void setArea(String area) {
        this.area = area;
    }

}

接下來為listview創建一個配接器，命名為HosptialAdapter 并繼承BaseAdapter，創建構造方法，連接子布局，如代碼所示：

package com.example.myapplication.ProgectOne;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.TextView;

import com.example.myapplication.HospitalActivity;
import com.example.myapplication.ListviewAdapter;
import com.example.myapplication.R;

import java.io.Serializable;
import java.util.List;

public class HosptialAdapter extends BaseAdapter {
    private Context context;
    private List<HospitalClass> list;
    public HosptialAdapter(Context context, List<HospitalClass> list) {
        this.context = context;
        this.list = list;
    }
    @Override
    public int getCount() {
        return list.size();
    }
    @Override
    public Object getItem(int i) {
        return list.get(i);
    }
    @Override
    public long getItemId(int i) {
        return i;
    }
    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {
        View view1= LayoutInflater.from(context).inflate(R.layout.layout_main2_item,null);
        final HospitalClass hospitalClass=list.get(i);
        TextView name=view1.findViewById(R.id.name2);
        TextView grade=view1.findViewById(R.id.grade2);
        TextView area=view1.findViewById(R.id.area2);
        Button button=view1.findViewById(R.id.button);
        name.setText(hospitalClass.getName());
        grade.setText(hospitalClass.getGrade()+"等級");
        area.setText(hospitalClass.getArea());
        return view1;
    }
}

接下來我們回到MainActivity2.java檔案中，宣告listview控制元件，定義一個List<HospitalClass>陣列，宣告RequeQuest，

package com.example.myapplication.ProgectOne;

import androidx.appcompat.app.AppCompatActivity;

import android.app.DownloadManager;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;
import android.widget.TextView;

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.JsonObjectRequest;
import com.android.volley.toolbox.Volley;
import com.example.myapplication.ListviewAdapter;
import com.example.myapplication.MainActivity;
import com.example.myapplication.R;

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

import java.util.ArrayList;
import java.util.List;

public class MainActivity2 extends AppCompatActivity {
    ListView listView;
    List<HospitalClass>  hospitalClassesList;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        listView=findViewById(R.id.listview2);
        hospitalClassesList=new ArrayList<>();
        initData();
    }
    private void initData() {
        //web訪問
        String url="http://smartcity.leeda.top/interface/SCHospital/getAll?userId=NzA2";
        //1.創建佇列
        final RequestQueue request= Volley.newRequestQueue(this);
        //創建json物件
        JsonObjectRequest jsonObjectRequest=new JsonObjectRequest(Request.Method.GET, url,
                null, new Response.Listener<JSONObject>() {
            @Override
            public void onResponse(JSONObject response) {
                try {
                    int status=response.getInt("status");
                    if(status==200){
                        //獲取data資料,回傳所有醫院的資料,,,JsonArray格式
                        String data=response.getString("data");
                        //陣列決議
                        JSONArray array=new JSONArray(data);
                        for (int i=0;i<array.length();i++){
                            //獲取JsonObject
                            JSONObject jsonObject=array.getJSONObject(i);
                            //每回圈一次，動態生成物體物件，每一條資料都是物體物件
                            HospitalClass hospitalClass=new HospitalClass();
                            hospitalClass.setName(jsonObject.getString("name"));
                            hospitalClass.setGrade(jsonObject.getInt("grade")+1);
                            hospitalClass.setArea(jsonObject.getString("region"));
                            hospitalClass.setId(jsonObject.getInt("id"));
                            hospitalClassesList.add(hospitalClass);
                        }
                        //決議完成后,給ListView系結配接器
                        HosptialAdapter hosptialAdapter=new HosptialAdapter(MainActivity2.this,hospitalClassesList);
                        listView.setAdapter(hosptialAdapter);
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }
            }
        }, new Response.ErrorListener() {
            @Override
            public void one rrorResponse(VolleyError error) {
            }
        });
        //將物件添加到佇列中
        request.add(jsonObjectRequest);
    }

}

最后在AndroMainifest.xml中添加過濾器后打開模擬器運行

<activity android:name=".MainActivity2">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
</activity>

運行結果：

小白在線如有誤歡迎指點，