第十二天 EventBus

标题 EventBus

1、什么是EventBus

EventBus is a publish/subscribe event bus for Android and Java.

2、特点优势

simplifies the communication between components
    decouples event senders and receivers
    performs well with Activities, Fragments, and background threads
    avoids complex and error-prone dependencies and life cycle issues
makes your code simpler
is fast
is tiny (~60k jar)
is proven in practice by apps with 1,000,000,000+ installs
has advanced features like delivery threads, subscriber priorities, etc.

3.步骤

1.依赖

 implementation 'org.greenrobot:eventbus:3.2.0'

2.定义事件（消息）

public class LoginSuccessEvent {
    
    
}

3.定义接收事件的方法 (用一个Fragment)

package com.example.myapplication;


import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;

import androidx.fragment.app.Fragment;

import org.greenrobot.eventbus.EventBus;


/**
 * A simple {@link Fragment} subclass.
 */
public class BlankFragment extends Fragment {
    
    


    private Button btn;

    public BlankFragment() {
    
    
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
    
    
        // Inflate the layout for this fragment
        View inflate = inflater.inflate(R.layout.fragment_blank, container, false);
        btn = (Button) inflate.findViewById(R.id.btn);
        btn.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                String s="哈哈";
                EventBus.getDefault().post(s);
            }
        });
        return inflate;
    }


}

activity

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

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/btn">

</Button>

</FrameLayout>

4.注册和反注册

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.Toast;

import org.greenrobot.eventbus.EventBus;
import org.greenrobot.eventbus.Subscribe;

public class MainActivity extends AppCompatActivity {
    
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    
    
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        EventBus.getDefault().register(this);
    }
    @Subscribe
    public void getString(String s){
    
    
        Toast.makeText(this, s, Toast.LENGTH_SHORT).show();
    }

    @Override
    protected void onDestroy() {
    
    
        super.onDestroy();
        EventBus.getDefault().unregister(this);
    }

}

activity

<?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"
    tools:context=".MainActivity">

<fragment
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/aa"
    android:name="com.example.myapplication.BlankFragment">

</fragment>

</LinearLayout>

作业

适配器

package com.example.a33zuoye;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import com.bumptech.glide.Glide;

import java.util.List;

public class FoodAdapter extends RecyclerView.Adapter<FoodAdapter.ViewHolder>{
    
    
    Context context;
    List<KaWaYi.DataBean> list;

    public FoodAdapter(Context context, List<KaWaYi.DataBean> list) {
    
    
        this.context = context;
        this.list = list;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    
    
        View inflate = LayoutInflater.from(context).inflate(R.layout.food_item, null);
        return new ViewHolder(inflate);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
    
    
        KaWaYi.DataBean dataBean = list.get(position);
        holder.textView.setText(dataBean.getTitle());
        Glide.with(context).load(dataBean.getUrl()).into(holder.imageView);
    }

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

    class ViewHolder extends  RecyclerView.ViewHolder{
    
    

        ImageView imageView;
        TextView textView;

        public ViewHolder(@NonNull View itemView) {
    
    
            super(itemView);
            imageView = itemView.findViewById(R.id.img);
            textView = itemView.findViewById(R.id.tv1);
        }
    }
}

图片资源

package com.example.a33zuoye;

import java.util.List;

public class KaWaYi {
    
    

    /**
     * data : [{"_id":"5e959250808d6d2fe6b56eda","author":"鸢媛","category":"Girl","createdAt":"2020-05-25 08:00:00","desc":"与其安慰自己平凡可贵，\n不如拼尽全力活得漂亮。 \u200b \u200b\u200b\u200b\u200b","images":["http://gank.io/images/f4f6d68bf30147e1bdd4ddbc6ad7c2a2"],"likeCounts":7,"publishedAt":"2020-05-25 08:00:00","stars":1,"title":"第96期","type":"Girl","url":"http://gank.io/images/f4f6d68bf30147e1bdd4ddbc6ad7c2a2","views":13477},{"_id":"5e95923f808d6d2fe6b56ed8","author":"鸢媛","category":"Girl","createdAt":"2020-05-24 08:00:00","desc":"这世界总有人在笨拙地爱着你，想把全部的温柔都给你。 \u200b\u200b\u200b\u200b","images":["http://gank.io/images/dc75cbde1d98448183e2f9514b4d1320"],"likeCounts":4,"publishedAt":"2020-05-24 08:00:00","stars":1,"title":"第95期","type":"Girl","url":"http://gank.io/images/dc75cbde1d98448183e2f9514b4d1320","views":5777},{"_id":"5e95922e808d6d2fe6b56ed6","author":"鸢媛","category":"Girl","createdAt":"2020-05-23 08:00:00","desc":"陪伴本来就是这世界上最了不起的安慰\u200b。","images":["http://gank.io/images/6b2efa591564475fb8bc32291fb0007c"],"likeCounts":1,"publishedAt":"2020-05-23 08:00:00","stars":1,"title":"第94期","type":"Girl","url":"http://gank.io/images/6b2efa591564475fb8bc32291fb0007c","views":5101},{"_id":"5e959200ee6ba981da2af34d","author":"鸢媛","category":"Girl","createdAt":"2020-05-22 08:00:00","desc":"长不过执念，短不过善变。","images":["http://gank.io/images/d6bba8cf5b8c40f9ad229844475e9149"],"likeCounts":2,"publishedAt":"2020-05-22 08:00:00","stars":1,"title":"第93期","type":"Girl","url":"http://gank.io/images/d6bba8cf5b8c40f9ad229844475e9149","views":4060},{"_id":"5e9591dcee6ba981da2af34b","author":"鸢媛","category":"Girl","createdAt":"2020-05-21 08:00:00","desc":"无论多么艰难的现在，终会翻篇。\n朝未来大步向前吧，别丧，别止步。","images":["http://gank.io/images/9fa43020cf724c69842eec3e13f6d21c"],"likeCounts":4,"publishedAt":"2020-05-21 08:00:00","stars":1,"title":"第92期","type":"Girl","url":"http://gank.io/images/9fa43020cf724c69842eec3e13f6d21c","views":2713},{"_id":"5e9591c60bd5529b54e712af","author":"鸢媛","category":"Girl","createdAt":"2020-05-20 08:00:00","desc":"希望下一次，能喜欢上一个也喜欢自己的人 \u200b\u200b\u200b\u200b。","images":["http://gank.io/images/d237f507bf1946d2b0976e581f8aab9b"],"likeCounts":0,"publishedAt":"2020-05-20 08:00:00","stars":1,"title":"第91期","type":"Girl","url":"http://gank.io/images/d237f507bf1946d2b0976e581f8aab9b","views":2279},{"_id":"5e9591b6808d6d2fe6b56ed5","author":"鸢媛","category":"Girl","createdAt":"2020-05-19 08:00:00","desc":"这个世界上，\n有些人有多冷漠，\n有些人就有多温暖，\n希望你总会遇到那些温暖对你的人。","images":["http://gank.io/images/25d3e3db2c1248bb917c09dc4f50a46f"],"likeCounts":1,"publishedAt":"2020-05-19 08:00:00","stars":1,"title":"第90期","type":"Girl","url":"http://gank.io/images/25d3e3db2c1248bb917c09dc4f50a46f","views":3147},{"_id":"5e9591a2ee6ba981da2af34a","author":"鸢媛","category":"Girl","createdAt":"2020-05-18 08:00:00","desc":"以前对你的喜欢，\n是见你，念你，陪伴你。\n现在对你的喜欢，\n是不问，不看，不叨扰。","images":["http://gank.io/images/19c99c447e0a40a6b3ff89951957cfb1"],"likeCounts":0,"publishedAt":"2020-05-18 08:00:00","stars":1,"title":"第89期","type":"Girl","url":"http://gank.io/images/19c99c447e0a40a6b3ff89951957cfb1","views":2143},{"_id":"5e959197808d6d2fe6b56ed4","author":"鸢媛","category":"Girl","createdAt":"2020-05-17 08:00:00","desc":"只要结局是喜剧，过程你要我怎么哭都行，幸福可以来的慢一些，\n只要它是真的，如果最后能在一起，晚点我真的无所谓的。","images":["http://gank.io/images/f0c192e3e335400db8a709a07a891b2e"],"likeCounts":0,"publishedAt":"2020-05-17 08:00:00","stars":1,"title":"第88期","type":"Girl","url":"http://gank.io/images/f0c192e3e335400db8a709a07a891b2e","views":3044},{"_id":"5e95915f808d6d2fe6b56ed3","author":"鸢媛","category":"Girl","createdAt":"2020-05-16 08:00:00","desc":"若不是情深似海，思念又怎会泛滥成灾。","images":["http://gank.io/images/bdb35e4b3c0045c799cc7a494a3db3e0"],"likeCounts":3,"publishedAt":"2020-05-16 08:00:00","stars":1,"title":"第87期","type":"Girl","url":"http://gank.io/images/bdb35e4b3c0045c799cc7a494a3db3e0","views":4498}]
     * page : 1
     * page_count : 10
     * status : 100
     * total_counts : 96
     */

    private int page;
    private int page_count;
    private int status;
    private int total_counts;
    private List<DataBean> data;

    public int getPage() {
    
    
        return page;
    }

    public void setPage(int page) {
    
    
        this.page = page;
    }

    public int getPage_count() {
    
    
        return page_count;
    }

    public void setPage_count(int page_count) {
    
    
        this.page_count = page_count;
    }

    public int getStatus() {
    
    
        return status;
    }

    public void setStatus(int status) {
    
    
        this.status = status;
    }

    public int getTotal_counts() {
    
    
        return total_counts;
    }

    public void setTotal_counts(int total_counts) {
    
    
        this.total_counts = total_counts;
    }

    public List<DataBean> getData() {
    
    
        return data;
    }

    public void setData(List<DataBean> data) {
    
    
        this.data = data;
    }

    public static class DataBean {
    
    
        /**
         * _id : 5e959250808d6d2fe6b56eda
         * author : 鸢媛
         * category : Girl
         * createdAt : 2020-05-25 08:00:00
         * desc : 与其安慰自己平凡可贵，
         不如拼尽全力活得漂亮。 ​ ​​​​
         * images : ["http://gank.io/images/f4f6d68bf30147e1bdd4ddbc6ad7c2a2"]
         * likeCounts : 7
         * publishedAt : 2020-05-25 08:00:00
         * stars : 1
         * title : 第96期
         * type : Girl
         * url : http://gank.io/images/f4f6d68bf30147e1bdd4ddbc6ad7c2a2
         * views : 13477
         */

        private String _id;
        private String author;
        private String category;
        private String createdAt;
        private String desc;
        private int likeCounts;
        private String publishedAt;
        private int stars;
        private String title;
        private String type;
        private String url;
        private int views;
        private List<String> images;

        public String get_id() {
    
    
            return _id;
        }

        public void set_id(String _id) {
    
    
            this._id = _id;
        }

        public String getAuthor() {
    
    
            return author;
        }

        public void setAuthor(String author) {
    
    
            this.author = author;
        }

        public String getCategory() {
    
    
            return category;
        }

        public void setCategory(String category) {
    
    
            this.category = category;
        }

        public String getCreatedAt() {
    
    
            return createdAt;
        }

        public void setCreatedAt(String createdAt) {
    
    
            this.createdAt = createdAt;
        }

        public String getDesc() {
    
    
            return desc;
        }

        public void setDesc(String desc) {
    
    
            this.desc = desc;
        }

        public int getLikeCounts() {
    
    
            return likeCounts;
        }

        public void setLikeCounts(int likeCounts) {
    
    
            this.likeCounts = likeCounts;
        }

        public String getPublishedAt() {
    
    
            return publishedAt;
        }

        public void setPublishedAt(String publishedAt) {
    
    
            this.publishedAt = publishedAt;
        }

        public int getStars() {
    
    
            return stars;
        }

        public void setStars(int stars) {
    
    
            this.stars = stars;
        }

        public String getTitle() {
    
    
            return title;
        }

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

        public String getType() {
    
    
            return type;
        }

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

        public String getUrl() {
    
    
            return url;
        }

        public void setUrl(String url) {
    
    
            this.url = url;
        }

        public int getViews() {
    
    
            return views;
        }

        public void setViews(int views) {
    
    
            this.views = views;
        }

        public List<String> getImages() {
    
    
            return images;
        }

        public void setImages(List<String> images) {
    
    
            this.images = images;
        }
    }
}

java代码

import android.os.Bundle;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.RecyclerView;
import androidx.recyclerview.widget.StaggeredGridLayoutManager;

import com.google.gson.Gson;
import com.lzy.okgo.OkGo;
import com.lzy.okgo.callback.StringCallback;
import com.lzy.okgo.model.Response;

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

public class MainActivity extends AppCompatActivity {
    List<KaWaYi.DataBean> list = new ArrayList<>();
    private RecyclerView re;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        final FoodAdapter foodAdapter = new FoodAdapter(this, list);
        re.setLayoutManager(new StaggeredGridLayoutManager(2,StaggeredGridLayoutManager.VERTICAL));
        re.setAdapter(foodAdapter);

        OkGo.<String>get("https://gank.io/api/v2/data/category/Girl/type/Girl/page/1/count/20").execute(new StringCallback() {
            @Override
            public void onSuccess(Response<String> response) {
                String body = response.body();
                KaWaYi kaWaYi = new Gson().fromJson(body, KaWaYi.class);
                List<KaWaYi.DataBean> data = kaWaYi.getData();
                list.addAll(data);
                foodAdapter.notifyDataSetChanged();
            }
        });


    }

    private void initView() {
        re = (RecyclerView) findViewById(R.id.re);
    }
}

activity

<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"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/re"
        />

</LinearLayout>

item

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal" android:layout_width="match_parent"
    android:layout_height="wrap_content">
<ImageView
    android:layout_width="100dp"
    android:layout_height="100dp"
    android:id="@+id/img"
    />
    <TextView
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:id="@+id/tv1"
        />
</LinearLayout>