第一阶段：冲刺5（android---新闻热搜界面设置）

今天一天都在搞热搜界面，之前学习过android的数据库操作，里面有个界面（下图）和热搜界面很像，都是分成一块一块的。于是今天就试着做了一下。本来想偷懒，复制项目，修改实体类等一些东西，但是最后改的时候改疯了。好多东西都忘了，在加上android的Room坑爹的操作，只要动了，实体类，就得改版本，报一堆乱七八糟的错误。最后我不得不自己重新敲了一遍。

这是我根据qq热搜和微博热搜设计的（忽略那两个键，clear不能用）：每一个都是一个小模块

目前只是页面的设计，自己添加东西。以后会实现从数据库里读取内容，然后显示到改页面中。

写这个页面用到的东西还挺多，包括数据库操作，工厂设计，viewModel，和LiveData（没想到一个页面让我弄得这么复杂）：

因为有数据库操作，所以得在gradle（Module：app）添加依赖如下：

def room_version = "2.2.2"
    implementation "androidx.room:room-runtime:$room_version"
    annotationProcessor "androidx.room:room-compiler:$room_version" // For Kotlin use kapt instead of annotationProcessor
    // Test helpers
    testImplementation "androidx.room:room-testing:$room_version"
    implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'
    implementation 'androidx.recyclerview:recyclerview:1.1.0'
    implementation 'androidx.cardview:cardview:1.0.0'

首先是一个子模块，就是我们每一个小块的内容：

<?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="60dp"
    android:background="?attr/selectableItemBackground"
    android:clickable="true">

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.1" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        app:layout_constraintGuide_percent="0.80" />

    <TextView
        android:id="@+id/textViewNumber"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="1"
        android:textSize="18sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/guideline2"
        app:layout_constraintHorizontal_bias="0.516"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textViewSearchNum"
        android:layout_width="66dp"
        android:layout_height="20dp"
        android:layout_marginTop="28dp"
        android:layout_marginBottom="23dp"
        android:text="233w人查询"
        android:textSize="10sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.562"
        app:layout_constraintStart_toStartOf="@+id/guideline3"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.545" />

    <EditText
        android:id="@+id/editTextTitle"
        android:layout_width="243dp"
        android:layout_height="40dp"
        android:ems="10"
        android:inputType="textPersonName"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toStartOf="@+id/guideline3"
        app:layout_constraintHorizontal_bias="0.294"
        app:layout_constraintStart_toStartOf="@+id/guideline2"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

然后是我们的主页面:用到了recyclerView

<?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=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/RecyclerView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.0"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="@+id/guideline"
        app:layout_constraintVertical_bias="1.0" />

    <androidx.constraintlayout.widget.Guideline
        android:id="@+id/guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_percent="0.15" />

    <Button
        android:id="@+id/buttonInsert"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Insert"
        app:layout_constraintBottom_toTopOf="@+id/guideline"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.126"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.58" />

    <Button
        android:id="@+id/buttonClear"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="clear"
        app:layout_constraintBottom_toTopOf="@+id/guideline"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.826"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.58" />
</androidx.constraintlayout.widget.ConstraintLayout>

新闻实体类：

展开查看

package com.example.hotsearch;
import androidx.room.ColumnInfo;

import androidx.room.Entity;

import androidx.room.PrimaryKey;
@Entity

public class New_ {

@PrimaryKey(autoGenerate = true)

private int id;

//    @ColumnInfo(name = "评论数量")

private int commentCount;

//    @ColumnInfo(name = "阅读量")

private int priority;

//    @ColumnInfo(name = "来源")

private String source;

//    @ColumnInfo(name = "标题")

private String title;

//    @ColumnInfo(name = "摘要")

private String digest;

//    @ColumnInfo(name = "图片地址")

private String imgsrc;

//    @ColumnInfo(name = "时间")

private String ptime;

//    @ColumnInfo(name = "正文")

private String zw;

//    @ColumnInfo(name = "类型")

private String type;

private Boolean history = false;
public New_(int priority, String title) {
    this.priority = priority;
    this.title = title;
}

public Boolean getHistory() {
    return history;
}

public void setHistory(Boolean history) {
    this.history = history;
}

public int getId() {
    return id;
}

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

public int getCommentCount() {
    return commentCount;
}

public void setCommentCount(int commentCount) {
    this.commentCount = commentCount;
}

public int getPriority() {
    return priority;
}

public void setPriority(int priority) {
    this.priority = priority;
}

public String getSource() {
    return source;
}

public void setSource(String source) {
    this.source = source;
}

public String getTitle() {
    return title;
}

public void setTitle(String title) {
    this.title = title;
}

public String getDigest() {
    return digest;
}

public void setDigest(String digest) {
    this.digest = digest;
}

public String getImgsrc() {
    return imgsrc;
}

public void setImgsrc(String imgsrc) {
    this.imgsrc = imgsrc;
}

public String getPtime() {
    return ptime;
}

public void setPtime(String ptime) {
    this.ptime = ptime;
}

public String getZw() {
    return zw;
}

public void setZw(String zw) {
    this.zw = zw;
}

public String getType() {
    return type;
}

public void setType(String type) {
    this.type = type;
}

}

数据库操作接口NewsDao

展开查看

package com.example.hotsearch;
import androidx.lifecycle.LiveData;

import androidx.room.Dao;

import androidx.room.Insert;

import androidx.room.Query;
import java.util.List;
@Dao

public interface NewsDao {

@Insert

public void insertNews(New_...new_s);

@Query("SElECT * FROM New_")

public LiveData<List<New_>> getAllNewsLive();

@Query("DELETE FROM New_")

public void deleteAllNews();

}

数据库NewsDataBase

展开查看

package com.example.hotsearch;
import android.content.Context;
import androidx.room.Database;

import androidx.room.Room;

import androidx.room.RoomDatabase;

@Database(entities = {New_.class},version = 1,exportSchema = false)

public abstract class NewsDatabase extends RoomDatabase {

private static NewsDatabase INSTANCE;

static synchronized NewsDatabase getDatabase(Context context){

if(INSTANCE == null){

INSTANCE = Room.databaseBuilder(context.getApplicationContext(),NewsDatabase.class,"new_database")

.allowMainThreadQueries()

.build();

}

return INSTANCE;

}

public abstract NewsDao getNewsDao();

}

工厂NewsRepository

展开查看

package com.example.hotsearch;
import android.content.Context;

import android.os.AsyncTask;
import androidx.lifecycle.LiveData;
import java.util.List;
public class NewsRepository {

private LiveData<List<New_>> allNews;

private NewsDao newsDao;

public NewsRepository(Context context) {

NewsDatabase wordDatabase = NewsDatabase.getDatabase(context.getApplicationContext());

newsDao = wordDatabase.getNewsDao();

allNews = newsDao.getAllNewsLive();

}
public LiveData<List<New_>> getAllNews() {
    return allNews;
}
// 定义类的接口-- 插入
public void insertNews(New_...news){
    new InsertAsyncTask(newsDao).execute(news);
}
// 插入类
static class InsertAsyncTask extends AsyncTask<New_,Void,Void> {
    private NewsDao newsDao;
    public InsertAsyncTask(NewsDao newsDao) {
        this.newsDao = newsDao;
    }
    // 将在主线程的工作放到后台来执行
    @Override
    protected Void doInBackground(New_...new_s) {
       newsDao.insertNews(new_s);
        return null;
    }
}

}

NewViewModel

展开查看

package com.example.hotsearch;
import android.app.Application;
import androidx.annotation.NonNull;

import androidx.lifecycle.AndroidViewModel;

import androidx.lifecycle.LiveData;
import java.util.List;
public class NewsViewModel extends AndroidViewModel {

private NewsRepository newsRepository;

public NewsViewModel(@NonNull Application application) {

super(application);

newsRepository = new NewsRepository(application);

}
public LiveData<List<New_>> getAllNews() {
    return newsRepository.getAllNews();
}

// 定义类的接口-- 插入
public void insertWords(New_...news){
   newsRepository.insertNews(news);
}

}

适配器MyAdapter

展开查看

package com.example.hotsearch;
import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.EditText;

import android.widget.TextView;

import androidx.annotation.NonNull;

import androidx.recyclerview.widget.RecyclerView;
import java.util.ArrayList;

import java.util.List;
public class MyAdapter extends RecyclerView.Adapter<MyAdapter.MyViewHolder> {

List<New_> allNews = new ArrayList<>();
public void setAllNews(List<New_> allNews) {
    this.allNews = allNews;
}

@NonNull
@Override
public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    LayoutInflater layoutInflater = LayoutInflater.from(parent.getContext());
    View itemViem = layoutInflater.inflate(R.layout.cell_normal, parent,false);
    return new MyViewHolder(itemViem);
}

@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {
    New_ new_ = allNews.get(position);
    holder.textViewNumber.setText(String.valueOf(position));
    holder.editTextTitle.setText(new_.getTitle());
    holder.textViewSearchNum.setText(new_.getPriority()+"人查询");
}

@Override
public int getItemCount() {
    return allNews.size();
}

//用来管理我们新建的ConstraintLayout
static class MyViewHolder extends RecyclerView.ViewHolder {
    TextView textViewNumber,textViewSearchNum;
    EditText editTextTitle;
    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        textViewNumber = itemView.findViewById(R.id.textViewNumber);
        editTextTitle = itemView.findViewById(R.id.editTextTitle);
        textViewSearchNum = itemView.findViewById(R.id.textViewSearchNum);
    }
}

}

MainActivity

展开查看

package com.example.hotsearch;
import androidx.appcompat.app.AppCompatActivity;

import androidx.lifecycle.LiveData;

import androidx.lifecycle.Observer;

import androidx.lifecycle.ViewModelProviders;

import androidx.recyclerview.widget.LinearLayoutManager;

import androidx.recyclerview.widget.RecyclerView;

import androidx.room.Room;
import android.os.AsyncTask;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;
import java.util.List;
public class MainActivity extends AppCompatActivity {

Button buttonInsert,buttonClear;

NewsViewModel newsViewModel;

RecyclerView recyclerView;

MyAdapter myAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    buttonInsert = findViewById(R.id.buttonInsert);
    buttonClear = findViewById(R.id.buttonClear);
    recyclerView = findViewById(R.id.RecyclerView);
    myAdapter = new MyAdapter();
    newsViewModel = ViewModelProviders.of(this).get(NewsViewModel.class);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setAdapter(myAdapter);
    newsViewModel.getAllNews().observe(this, new Observer<List<New_>>() {
        @Override
        public void onChanged(List<New_> new_s) {
            myAdapter.setAllNews(new_s);
            myAdapter.notifyDataSetChanged();
        }
    });
    buttonInsert.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            New_ new_2 = new New_(400,"aaa");
            newsViewModel.insertWords(new_2);
        }
    });

}

}