android data binding jetpack V _Android

亦余心之所善兮，虽九死其犹未悔。这篇文章主要讲述android data binding jetpack V相关的知识，希望能为你提供帮助。
android data binding jetpack VIII BindingConversion
android data binding jetpack VII @BindingAdapter
android data binding jetpack V 实现recyclerview 绑定
android data binding jetpack IV 绑定一个方法另一种写法和参数传递
android data binding jetpack III 绑定一个方法
android data binding jetpack II 动态数据更新
android data binding jetpack I 环境配置 model-view 简单绑定

来实现一个recyclerview绑定。
看了例子理一下思路。

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第一个关系：
item 与itemview 数据与展示绑定。
recyclerview 更新数据和UI过程是：获取holder类型-> 产生holder-> 获取holder（）-> holder+data-> 展示。
代码在adapter中执行。
1.获取某个位置的holder类型。

@Override public int getItemViewType(int position) { return super.getItemViewType(position); }

2.创建holder

@Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {return viewHolder; }

3.绑定数据并展示出来。

@Override public void onBindViewHolder(ViewHolder holder, int position) {}

现在使mvvm 那么
第一步：在createholder的时候要确定 binding 与xml的绑定关系。
第二步：在onBindViewHolder中让关系实现并展示。
看示例代码怎么实现第一步

@Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//读取xml对内存 LayoutInflater inflater = LayoutInflater.from(parent.getContext()); //建立绑定关系
ViewDataBinding binding = DataBindingUtil.inflate(inflater, layoutId, parent, false); //建立一下holder
ViewHolder viewHolder = new ViewHolder(binding.getRoot()); //把绑定关系记录在holder的变量里。
viewHolder.setBinding(binding); return viewHolder; }

@Override public void onBindViewHolder(ViewHolder holder, int position) {
//执行绑定，给绑定关系设置数据。 holder.getBinding().setVariable(brId,mDatas.get(position));
//让绑定生效。 holder.getBinding().executePendingBindings(); }

< ?xml version="1.0" encoding="utf-8"?> < layout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto"> < data> < import type="com.ht.jetpack.model.Student" /> < variable name="student" type="Student" /> < /data> < LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:gravity="center"> < ImageView android:layout_width="280dp" android:layout_height="210dp" android:layout_margin="10dp" android:scaleType="centerCrop" app:studentAvatar="@{student.resId}" /> < TextView android:layout_width="fill_parent" android:layout_height="wrap_content" android:layout_marginLeft="40dp" android:gravity="center" android:text="@{student.name}" android:textSize="18sp" /> < /LinearLayout> < /layout>

xml是绑定关系。
整个过程：加xml-> 产生绑定关-> 滚动到某个位置-> 获取绑定关系，给绑定加入数据-> 展示

声明的变量：

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给变量赋值：

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brId是

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就是xml里声明的模型变量。
难点：

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这个之前没有见过。自定义了一个属性，进行了绑定。
具定实现在这儿：

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这个需要求单独一下块内容去学习。
看一下运行效果：

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以下是实例代码：要运行请自己找几张图加到drawable里命名一致就可以了。

package com.ht.jetpack.adapter; import android.databinding.BindingAdapter; import android.widget.ImageView; public class BindingUtil {@BindingAdapter("bind:studentAvatar") public static void showImageByUrl(final ImageView imageView, int resId) { imageView.setImageResource(resId); } }

package com.ht.jetpack.adapter; import android.content.Context; import android.support.v7.widget.DefaultItemAnimator; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.support.v7.widget.StaggeredGridLayoutManager; public class InitRecyclerView {public static void initLinearLayoutVERTICAL(Context context, RecyclerView recyclerView) { LinearLayoutManager layoutManager = new LinearLayoutManager(context); layoutManager.setOrientation(LinearLayoutManager.VERTICAL); recyclerView.setLayoutManager(layoutManager); recyclerView.setItemAnimator(new DefaultItemAnimator()); }public static void initLinearLayoutWithoutDivid(Context context, RecyclerView recyclerView) { LinearLayoutManager layoutManager = new LinearLayoutManager(context); layoutManager.setOrientation(LinearLayoutManager.VERTICAL); recyclerView.setLayoutManager(layoutManager); recyclerView.setItemAnimator(new DefaultItemAnimator()); }public static void initLinearLayoutHorizontal(Context context, RecyclerView recyclerView) { LinearLayoutManager layoutManager = new LinearLayoutManager(context); layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL); recyclerView.setLayoutManager(layoutManager); recyclerView.setItemAnimator(new DefaultItemAnimator()); }public static void initStaggered(Context context, RecyclerView recyclerView) { StaggeredGridLayoutManager sgm = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL); recyclerView.setLayoutManager(sgm); recyclerView.setItemAnimator(new DefaultItemAnimator()); } }

package com.ht.jetpack.adapter; import android.databinding.DataBindingUtil; import android.databinding.ViewDataBinding; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.ViewGroup; import java.util.List; /** * Created by hongtao */ public class MySimpleAdapter< T> extends RecyclerView.Adapter< ViewHolder> {private List< T> mDatas; private int layoutId; private int brId; public MySimpleAdapter(List< T> mDatas, int layoutId, int brId) { this.mDatas = mDatas; this.layoutId = layoutId; this.brId = brId; }@Override public int getItemViewType(int position) { return super.getItemViewType(position); }@Override public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { LayoutInflater inflater = LayoutInflater.from(parent.getContext()); ViewDataBinding binding = DataBindingUtil.inflate(inflater, layoutId, parent, false); ViewHolder viewHolder = new ViewHolder(binding.getRoot()); viewHolder.setBinding(binding); return viewHolder; }@Override public void onBindViewHolder(ViewHolder holder, int position) { holder.getBinding().setVariable(brId,mDatas.get(position)); holder.getBinding().executePendingBindings(); }@Override public int getItemCount() { return mDatas == null ? 0 : mDatas.size(); } }

package com.ht.jetpack.adapter; import android.databinding.ViewDataBinding; import android.support.v7.widget.RecyclerView; import android.view.View; /** * Created by hongtao . */ public class ViewHolder extends RecyclerView.ViewHolder {private ViewDataBinding binding; public ViewDataBinding getBinding() { return binding; }public void setBinding(ViewDataBinding binding) { this.binding = binding; }public ViewHolder(View itemView) { super(itemView); } }

RecyclerView recyclerView = (RecyclerView) findViewById(R.id.show_list); InitRecyclerView.initLinearLayoutWithoutDivid(this, recyclerView); List< Student> students = new ArrayList< > (); Student student = new Student(R.drawable.tx2, "Kate"); students.add(student); student = new Student(R.drawable.tx3, "tom"); students.add(student); student = new Student(R.drawable.tx4, "Johnson"); students.add(student); student = new Student(R.drawable.tx5, "Make"); students.add(student); MySimpleAdapter< Student> adapter = new MySimpleAdapter< > (students, R.layout.student_item, BR.student); recyclerView.setAdapter(adapter);

在main layout里声明
< android.support.v7.widget.RecyclerView android:id="@+id/show_list" android:layout_width="match_parent" android:layout_height="match_parent" android:layout_above="@+id/navigation" android:layout_below="@id/tv" android:scrollbars="vertical" />

【android data binding jetpack V】