Android——Fresco、EventBus、GreenDao、Butterknife、Retrofit综合使用

谁践踏了优雅 2022-06-04 03:45 216阅读 0赞

**一、案例效果图**

**![Center][]      ![Center 1][]**

**二、技能描述**

通过Retrofit进行网络请求数据，要求后两个参数（下方接口地址中的10和1）通过注解方式传进去，

使用RecyclerView进行列表展示，请求到数据之后，使用GreenDao进行数据缓存，当进入页面时，

先从数据库中取数据，进行展示，再进行网络请求，有数据就更新，没有网络情况下只显示数据库中数据。

进入页面后判断网络状态，通过EventBus发送网络状态并Toast显示，使用ButterKnife进行视图注入，

使用Fresco进行列表图片展示。

**接口地址**

http://gank.io/api/data/Android/10/1

**三、实现思路**

1. 实现整体页面布局，下方5个底部菜单选项，上方添加5个Fragment

2. 导入Fresco，EventBus，GreenDao，Butterknife，Retrofit等的依赖

3. 进入页面后进行网络状态判断，判断后把状态通过EventBus进行发送并Toast显示

4. 创建试题类型，并通过GreenDao生成相应的表结构，进入页面后，进行数据库查询，

将查询到到的数据保存到List中

5. 使用RecyclerView进行列表展示，为RecyclerView创建适配器，使用ButterKnife为ViewHolder注入视图，

重写适配器方法，通过Fresco展示图片

6. 为RecyclerView设置适配器，当有网络时进行网络请求，初始化Retrofit对象，创建接口类，通过注解的方式

设置参数，执行网络请求自动解析数据，如果数据不为空的情况则更新List并更新数据库，刷新列表数据，

7. 断开网络，重新进入，测试数据库缓存是否生效

**添加依赖**

添加greendao的依赖需要先在APP下的build.gradle进行配置

// Top-level build file where you can add configuration options common to all sub-projects/modules.
    
    buildscript {
        repositories {
            jcenter()
            mavenCentral()//加入greendao
        }
        dependencies {
            classpath 'com.android.tools.build:gradle:2.3.3'
            classpath 'org.greenrobot:greendao-gradle-plugin:3.2.2'//加入greendao
            // NOTE: Do not place your application dependencies here; they belong
            // in the individual module build.gradle files
        }
    }
    
    allprojects {
        repositories {
            jcenter()
        }
    }
    
    task clean(type: Delete) {
        delete rootProject.buildDir
    }

在项目的build.gradle中添加依赖

apply plugin: 'com.android.application'
    apply plugin: 'org.greenrobot.greendao'//加入greendao
    android {
        compileSdkVersion 26
        buildToolsVersion "26.0.2"
        defaultConfig {
            applicationId "com.bwie.com.oneweekdemo"
            minSdkVersion 19
            targetSdkVersion 26
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        }
        buildTypes {
            release {
                minifyEnabled false
                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
            }
        }
    }
    
    dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
            exclude group: 'com.android.support', module: 'support-annotations'
        })
        compile 'com.android.support:appcompat-v7:26.+'
        compile 'com.android.support.constraint:constraint-layout:1.0.2'
        testCompile 'junit:junit:4.12'
        compile 'com.squareup.retrofit2:retrofit:2.0.0-beta4'  //Retrofit2所需要的包
        compile 'com.squareup.retrofit2:converter-gson:2.0.0-beta4'  //ConverterFactory的Gson依赖包
    
        compile'org.greenrobot:greendao:3.2.2'//greendao
        compile'org.greenrobot:greendao-generator:3.2.2'//greendao
    
        compile 'com.android.support:recyclerview-v7:26.0.0-alpha1'//recyclerview
        compile 'com.hjm:BottomTabBar:1.1.1'//底部导航栏
        compile 'org.greenrobot:eventbus:3.1.1'//enentbus
    
        compile 'com.jakewharton:butterknife:8.8.1'
        annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'//butterknife
    
        compile 'com.facebook.fresco:fresco:0.12.0'//fresco
    
    
    }

//加入greendao
    greendao {
        schemaVersion 1
        daoPackage 'com.bwie.com.oneweekdemo.gen'
        targetGenDir 'src/main/java'
    }

**网络权限**

<uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>

ResultsBean（参考）

@Entity
    public class ResultsBean {
        @Id
        private String _id;
        private String createdAt;
        private String desc;
        private String publishedAt;
        private String source;
        private String type;
        private String url;
        private boolean used;
        private String who;
        @Convert(columnType = String.class, converter = StringConverter.class)
        private List<String> images;

User中有一种List类型的数据也需要保存到数据库中，该如何处理呢？

答案很简单，可以转换一下思路，遍历List数据，然后将所有的String对象都append到一个StringBuilder中，

然后保存在数据库中即可。事实上，GreenDao已经为我们考虑到了这种情况，因此才有了 PropertyConverter

这个接口

**StringConverter**

/**
     * Created by Wangrx on 2017/12/2.
     */
    
    public class StringConverter implements PropertyConverter<List<String>, String> {
    
        @Override
        public List<String> convertToEntityProperty(String databaseValue) {
            if (databaseValue == null) {
                return null;
            }
            else {
                List<String> list = Arrays.asList(databaseValue.split(","));
                return list;
            }
        }
    
        @Override
        public String convertToDatabaseValue(List<String> entityProperty) {
            if(entityProperty==null){
                return null;
            }
            else{
                StringBuilder sb= new StringBuilder();
                for(String link:entityProperty){
                    sb.append(link);
                    sb.append(",");
                }
                return sb.toString();
            }
        }
    }

BlogService接口定义

`/** * Created by Wangrx on 2017/12/2. */ public interface BlogService { @GET("10/1") Call<JavaBean> getUrl(); }`

RetrofitUtils（Retrofit封装）`/** * Created by Wangrx on 2017/12/2. */ public class RetrofitUtils { private static volatile RetrofitUtils instance; private Retrofit retrofit; private RetrofitUtils(){ } private RetrofitUtils(String baseUrl){ retrofit = new Retrofit.Builder() .addConverterFactory(GsonConverterFactory.create()) .baseUrl(baseUrl) .build(); } public static RetrofitUtils getInstance(String baseUrl){ if (instance==null){ synchronized (RetrofitUtils.class){ if (null==instance){ instance = new RetrofitUtils(baseUrl); } } } return instance; } public static RetrofitUtils getInstance(){ if (null == instance){ return getInstance("http://gank.io/api/data/Android/"); } return instance; } public Retrofit getRetrofit(){ return retrofit; } }`

DBUtils（greendao封装）`/** * Created by Wangrx on 2017/12/2. */ public class DBUtils { private static volatile DBUtils instance; private final ResultsBeanDao dao; public DBUtils(Context context){ DaoMaster.DevOpenHelper helper = new DaoMaster.DevOpenHelper(context, "resultsbean.db", null); SQLiteDatabase database = helper.getWritableDatabase(); DaoMaster daoMaster = new DaoMaster(database); DaoSession daoSession = daoMaster.newSession(); dao = daoSession.getResultsBeanDao(); } public static DBUtils getInstance(Context context){ if (null==instance){ synchronized (DBUtils.class){ if (null==instance){ instance = new DBUtils(context); } } } return instance; } public ResultsBeanDao getDao(){ return dao; } }`

BaseApplication（存放本地数据，继承Application，初始化Fresco）`/** * Created by Wangrx on 2017/12/2. */ public class BaseApplication extends Application{ private static BaseApplication instance; private List<ResultsBean> list; @Override public void onCreate() { super.onCreate(); instance=this; Fresco.initialize(this);//初始化Fresco类 } public static BaseApplication getInstance(){ return instance; } public List<ResultsBean> getData(){ if (list==null){ list=new ArrayList<>(); } return list; } public void setData(List<ResultsBean> list){ this.list = list; } }`

MessageEvent(EventBus定义事件的类)`/** * Created by Wangrx on 2017/12/2. */ public class MessageEvent { private boolean connected; public boolean isConnected() { return connected; } public void setConnected(boolean connected) { this.connected = connected; } }`

MainActivity`public class MainActivity extends AppCompatActivity { private BottomTabBar mb; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //注册 EventBus.getDefault().register(this); mb = (BottomTabBar) findViewById(R.id.bottom_tab_bar); mb.init(getSupportFragmentManager()) .setImgSize(50, 50) .setFontSize(8) .setTabPadding(4, 6, 10) .setChangeColor(Color.RED, Color.DKGRAY) .addTabItem("首页", R.mipmap.shouye, FragmentShow.class) .addTabItem("分类", R.mipmap.fenlei, FragmentFen.class) .addTabItem("优惠", R.mipmap.youhui, FragmentYou.class) .addTabItem("购物车", R.mipmap.gouwuche, FragmentCart.class) .addTabItem("我的", R.mipmap.people, FragmentMy.class) .isShowDivider(true) .setOnTabChangeListener(new BottomTabBar.OnTabChangeListener() { @Override public void onTabChange(int position, String name) { } }); } @Subscribe() public void getConnected(MessageEvent event){ if (event.isConnected()){ Toast.makeText(this, "当前网络状态良好", Toast.LENGTH_SHORT).show(); }else { Toast.makeText(this, "当前网络不可用", Toast.LENGTH_SHORT).show(); } } @Override public void onDestroy() { super.onDestroy(); EventBus.getDefault().unregister(this); } }`

FragmentShow`/** * Created by Wangrx on 2017/12/2. */ public class FragmentShow extends Fragment{ private Retrofit retrofit; private ResultsBeanDao dao; private List<ResultsBean> data; private RecyclerView recyView; private MyAdapter adapter; @Nullable @Override public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { View view = View.inflate(getContext(), R.layout.fragmertshow, null); recyView = view.findViewById(R.id.recy_view); return view; } @Override public void onActivityCreated(@Nullable Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); dao = DBUtils.getInstance(getContext()).getDao(); boolean connected = isNetworkConnected(getActivity()); Log.i("zzz", "onCreate: "+connected); MessageEvent event = new MessageEvent(); event.setConnected(connected); EventBus.getDefault().post(event); initView(); } private void initView() { data = BaseApplication.getInstance().getData(); LinearLayoutManager manager = new LinearLayoutManager(getContext()); recyView.setLayoutManager(manager); adapter = new MyAdapter(getContext(), data); recyView.setAdapter(adapter); if (data == null || data.size() == 0) { Log.i("zzz", "内存中无数据"); //从数据库中取 List<ResultsBean> dataFromDB = getDataFromDB(); //数据库中也是空 if (dataFromDB==null||dataFromDB.size()==0){ Log.i("zzz", "数据控中为空"); //从网络中取数据 getDataFromNet(); }else { Log.i("zzz", "数据库中不为空"); putDataToMemory(dataFromDB); } } if (data==null||data.size()==0){ Log.i("zzz", "内存中无数据"); List<ResultsBean> dataFromDB = getDataFromDB(); if (dataFromDB==null||dataFromDB.size()==0){ Log.i("zzz", "数据库中为空"); getDataFromNet(); }else { putDataToMemory(dataFromDB); } } } public void getDataFromNet(){ retrofit = RetrofitUtils.getInstance().getRetrofit(); BlogService service = retrofit.create(BlogService.class); Call<JavaBean> call = service.getUrl(); call.enqueue(new Callback<JavaBean>() { @Override public void onResponse(Call<JavaBean> call, Response<JavaBean> response) { List<ResultsBean> results = response.body().getResults(); Log.i("zzz", "onResponse: "+data.toString()); if (results!=null){ Log.i("zzz", "网络不为空"); putDataToMemory(results); for (ResultsBean databean:results){ dao.insertOrReplace(databean); } } } @Override public void onFailure(Call<JavaBean> call, Throwable t) { Toast.makeText(getContext(), t.getMessage(), Toast.LENGTH_SHORT).show(); } }); } private void putDataToMemory(List<ResultsBean> list) { Log.i("zzz", "向内存中存数据"); data.clear(); data.addAll(list); adapter.notifyDataSetChanged(); BaseApplication.getInstance().setData(data); } //从数据库中取数据 public List<ResultsBean> getDataFromDB(){ Log.i("zzz", "从数据库中取"); //查询所有数据 List<ResultsBean> dataBeen = dao.loadAll(); if (dataBeen==null||dataBeen.size()==0){ Log.i("zzz", "null"); }else { Log.i("zzz", "getDataFromDB: "+dataBeen.size()); } return dataBeen; } public boolean isNetworkConnected(Context context) { if (context != null) { ConnectivityManager mConnectivityManager = (ConnectivityManager) context .getSystemService(Context.CONNECTIVITY_SERVICE); NetworkInfo mNetworkInfo = mConnectivityManager.getActiveNetworkInfo(); if (mNetworkInfo != null) { return mNetworkInfo.isAvailable(); } } return false; } }`

**MyAdapter(多条目加载)**`/** * Created by Wangrx on 2017/12/2. */ public class MyAdapter extends RecyclerView.Adapter { public static final int TYPE_ONE_IMAGE = 0; public static final int TYPE_TWO_IMAGE = 1; private Context context; private List<ResultsBean> list; public MyAdapter(Context context, List<ResultsBean> list) { this.context = context; this.list = list; } @Override public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { View view; RecyclerView.ViewHolder holder = null; switch (viewType) { case 0: view = View.inflate(context, R.layout.item, null); holder = new OneViewHolder(view); break; case 1: view = View.inflate(context, R.layout.twoitem, null); holder = new TwoViewHolder(view); } return holder; } @Override public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) { switch (getItemViewType(position)) { case 0: OneViewHolder holderOne = (OneViewHolder) holder; holderOne.itemDesc.setText(list.get(position).getDesc()); holderOne.itemType.setText(list.get(position).getType()); break; case 1: TwoViewHolder holdertwo = (TwoViewHolder) holder; List<String> images = list.get(position).getImages(); if (images != null && images.size() != 0) { // Glide.with(context).load(images.get(0)).into(holdertwo.itemImg); holdertwo.itemImage.setImageURI(images.get(0)); } holdertwo.itemDesc.setText(list.get(position).getDesc()); holdertwo.itemType.setText(list.get(position).getType()); } } @Override public int getItemViewType(int position) { List<String> images = list.get(position).getImages(); if (images != null && images.size() != 0) { return TYPE_TWO_IMAGE; } else { return TYPE_ONE_IMAGE; } } @Override public int getItemCount() { return list.size(); } public class OneViewHolder extends RecyclerView.ViewHolder { @BindView(R.id.item_desc) TextView itemDesc; @BindView(R.id.item_type) TextView itemType; public OneViewHolder(View itemView) { super(itemView); ButterKnife.bind(this, itemView); } } public class TwoViewHolder extends RecyclerView.ViewHolder { @BindView(R.id.item_image) SimpleDraweeView itemImage; @BindView(R.id.item_desc) TextView itemDesc; @BindView(R.id.item_type) TextView itemType; public TwoViewHolder(View itemView) { super(itemView); ButterKnife.bind(this, itemView); } } }`

activity\_main.xml

<?xml version="1.0" encoding="utf-8"?>
    <RelativeLayout 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="com.bwie.com.oneweekdemo.MainActivity">
        <com.hjm.bottomtabbar.BottomTabBar
            android:id="@+id/bottom_tab_bar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            >
        </com.hjm.bottomtabbar.BottomTabBar>
    
    
    </RelativeLayout>

[Center]: https://img-blog.csdn.net/20171203192545800?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQveHk4MTk5/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center
[Center 1]: /images/20220604/97d4b633f2a44290ac2bb687e95c9db8.png