手把手教你完成Android期末大作业（多功能应用型APP）(1)_安卓大作业

public class Weather {

private String city;		//城市名

private String update_time;	//更新时间

private List<DayData> data;	//每天的天气数据列表，data.get(0)为当天数据



/* 

	getter and setter 

*/
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}

// class DayData

public class DayData {

private String wea;			//天气状况

private String tem;			//当前温度

private String tem1;		//最高温

private String tem2;		//最低温

private String humidity; 	//湿度

private String air_level;	//空气质量等级

private String air_tips;	//空气质量小提示



/* 

	getter and setter 

*/
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}

4、由于OkHttp的请求是在子线程中进行的，需要使用Handler消息队列机制将解析出来的Weather实例发送到主线程用以显示在界面上。



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//消息处理类

public class MyHandler extends Handler {

@Override

public void handleMessage(@NonNull Message msg) {

    super.handleMessage(msg);

    //what == 1   天气消息

    if (msg.what == 1)

        ShowWeatherInfo((Weather) msg.obj);

}
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}

public void ShowWeatherInfo(Weather weather) {

String city = weather.getCity();

String wea = weather.getData().get(0).getWea();

String maxTem = weather.getData().get(0).getTem1();

String minTem = weather.getData().get(0).getTem2();

String tem = weather.getData().get(0).getTem();

String humidity = "湿度           " + weather.getData().get(0).getHumidity();

String air_level = "空气指数   " + weather.getData().get(0).getAir_level();



// tem  tem1  tem2  city  wea  rain  pm  image

((TextView) findViewById(R.id.cityView)).setText(city);

((TextView) findViewById(R.id.weaView)).setText(wea);

((TextView) findViewById(R.id.mmtemView)).setText(

    String.format("%s° / %s°", minTem.substring(0, minTem.length() - 1), maxTem.substring(0, maxTem.length() - 1)));

((TextView) findViewById(R.id.temView)).setText(tem.substring(0, tem.length() - 1) + "°");

((TextView) findViewById(R.id.humidityView)).setText(humidity);

((TextView) findViewById(R.id.levelView)).setText(air_level);



ShowWeatherImage(wea);	//根据天气状况wea显示对应的天气图片，这里不详细说明，使用switch就行
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}

5、别忘了在OkHttp请求完成时发送消息



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public void RefreshWeatherData() {

OkHttpClient client = new OkHttpClient();

Request request = new Request.Builder().url(weatherUrl).build();

client.newCall(request).enqueue(new Callback() {

    @Override

    public void onFailure(@NonNull Call call, @NonNull IOException e) {

        e.printStackTrace();

    }



    @Override

    public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException {

        String weatherJson = response.body().string();

        Weather weather = new Gson().fromJson(weatherJson, Weather.class);

        Message message = new Message();

        message.what = 1;

        message.obj = weather;

        myHandler.sendMessage(message);

    }

});
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}

6、优化xml布局



[]( )三、待办事项界面

-------------------------------------------------------------------



这里由于ListView是放在Fragment中的，所以直接在MainAcitivity.java中设置适配器可能会出现数据没法显示的bug。所以我直接把从数据库获取数据,Adapter的定义，ListView设置适配器的模块搬到了TaskFragment.java中。



1.在task.xml中添加ListView，先不用设置UI样式，先把数据拿到并显示在界面上



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<?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"

android:orientation="vertical">

<TextView

    android:id="@+id/taskText"

    android:layout_width="wrap_content"

    android:layout_height="wrap_content"

    android:text="事项"/>

<ListView

    android:id="@+id/taskListView"

    android:layout_width="match_parent"

    android:layout_height="match_parent"/>
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2.创建task\_item.xml布局文件(这里注意线性布局的方向及宽高，以保证task\_item能放在ListView中)



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<?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="wrap_content">



<TextView

    android:id="@+id/task_content"

    android:layout_width="match_parent"

    android:layout_height="wrap_content"

    android:textColor="@color/black"

    android:textSize="30dp"

    android:text="TextView" />
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3.新建TaskItem类，存放事项数据



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package com.example.daily.tasks;

public class TaskItem {

private int id;

private String content;

private String type;

private int status;



public TaskItem(int id, String type, String content, int status){

    this.id = id;

    this.type = type;

    this.content = content;

    this.status = status;

}



// 自行添加Get和Set方法
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}

4.在TaskFragment.java中创建SQLite数据库并获取待办事项的数据



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public class TaskFragment extends Fragment {

private static final String TAG = TaskFragment.class.getName();

private List<TaskItem> taskList = new ArrayList<>();



@Nullable

@Override

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.task, container, false);

    

    ReadTaskDataFromSQL();



    //测试数据获取是否正常

    for(TaskItem item : taskList){

        Log.i(TAG, "taskList "+item.getId()+" "+item.getContent());

    }

       

    return view;

}



//读取数据库并将数据存到taskList

public void ReadTaskDataFromSQL(){

    MySQLiteOpenHelper openHelper = new MySQLiteOpenHelper(getActivity());

    SQLiteDatabase readDatabase = openHelper.getReadableDatabase();

    

    Cursor cursor = readDatabase.query(

            "task",

        	new String[]{"id", "type", "content", "status"},

        	null,null,null,null,null

    );

    

    while(cursor.moveToNext()){

        TaskItem task = new TaskItem(

                cursor.getInt(0), 

                cursor.getString(1), 

                cursor.getString(2), 

                cursor.getInt(3)

        );

        taskList.add(task);

    }

    

}



//创建SQLite数据库

public class MySQLiteOpenHelper extends SQLiteOpenHelper{



    public MySQLiteOpenHelper(@Nullable Context context) {

        super(context, "Daily.db", null, 1);

    }



    @Override

    public void onCreate(SQLiteDatabase db) {

        Log.i(TAG, "onCreate: sqlite");

        //创建待办事项数据表

        String create_sql =

                "create table task(" +

                        "id INTEGER PRIMARY KEY AUTOINCREMENT, " +

                        "content varchar(50), " +

                        "type varchar(50), " +

                        "status int);";

        db.execSQL(create_sql);

    }

    

    @Override

    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {}

}
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}

5.数据获取正常以后，建立ListView适配器。这里涉及到缓存convertView的使用，使用convertView可以防止每创建一个item时就解析一个布局，这样效率肯定不高。convertView是Android提供的用于缓存的View，在第一次渲染item时，将将解析出来的View放入缓存convertView，在下一次渲染item的时候，判断convertView是否为空即可。



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public class TaskAdapter extends BaseAdapter{

@Override

public int getCount() {

    //测试getCount返回值是否正常

    Log.i(TAG, "getCount: "+taskList.size());

    return taskList.size();

}



@Override

public Object getItem(int position) {

    return taskList.get(position);

}



@Override

public long getItemId(int position) {

    return taskList.get(position).getId();

}



@Override

public View getView(int position, View convertView, ViewGroup parent) {

    //测试getView是否执行

    Log.i(TAG, "getView: "+position);



    ViewHolder viewHolder;

    TaskItem task = (TaskItem) getItem(position);



    if(convertView == null){

        viewHolder = new ViewHolder();

        convertView = LayoutInflater.from(getActivity()).inflate(R.layout.task_item, null);

        viewHolder.taskItemTextView = convertView.findViewById(R.id.task_content);



        convertView.setTag(viewHolder);

    }else{

        viewHolder = (ViewHolder) convertView.getTag();

    }



    viewHolder.taskItemTextView.setText(task.getId()+"  "+task.getContent());



    return convertView;

}
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}

public class ViewHolder{

TextView taskItemTextView;
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}

6.在onCreateView中设置ListView的适配器



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private List taskList = new ArrayList<>();

private TaskAdapter taskAdapter;

private ListView taskListView;

@Nullable

@Override

public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {

View view = inflater.inflate(R.layout.task, container, false);



taskListView = view.findViewById(R.id.taskListView);



taskAdapter = new TaskAdapter();



taskListView.setAdapter(taskAdapter);



ReadTaskDataFromSQL();

return view;
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}

**7.设计每一条待办事项的布局样式，如图所示，布局设计就不放原码了，使用多个线性布局的嵌套,gravity,margin属性即可实现。**



**img：task-2.jpg**



**8.根据待办事项的状态显示不同按钮，并标记待办事项的重要程度。**



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public void ShowTaskContent(View convertView, TaskItem task){

	//显示事项内容

    TextView content = ((ViewHolder) convertView.getTag()).taskContent;

    int status = task.getStatus();



    content.setText(task.getContent());



    //事项已完成 中划线 灰色

    if(status == 1){

        content.getPaint().setFlags(Paint.STRIKE_THRU_TEXT_FLAG);

        content.setTextColor(getResources().getColor(R.color.GRAY, null));

    }

    //事项未完成 无中划线 黑色

    if(status == 0){

        content.
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