android开发步步为营之85:RecyclerView简单使用_recyclerview android:scaletype="fitxy-优快云博客

本文介绍如何用RecyclerView替代GridView和ListView以提升应用性能。通过实例演示了RecyclerView的基本使用方法，包括依赖引入、页面设计及Activity编写等步骤，并展示了不同布局管理器的效果。

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最近项目里优化的时候，之前使用GridView和ListView的，然后统一改成了RecyclerView，发现性能能提升不少，左右滑动的时候，比之前更顺畅，从字面意思来看：可回收的View，自然对提升性能方面会比较好，还没仔细研究源码，这里给出简单使用，供大家参考，其实有了这个view，GridView和ListView可以不用了。它都能实现，好，贴出代码。

第一步：引入相关的依赖

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile files('src/main/libs/universal-image-loader-1.9.3.jar')
    compile 'com.android.support:support-v4:22.2.1'
    compile 'com.android.support:recyclerview-v7:22.2.0'
}

第二步：设计相关页面

activity页面activity_recycler_view.xml

<RelativeLayout 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"
    android:background="#c5efc6"
    tools:context="com.figo.study.activity.RecyclerViewActivity">

    <android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
        android:id="@+id/recyclerView_test"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</RelativeLayout>

RecyclerView头部layout_rv_head.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:background="#ffffff"
    android:layout_width="match_parent" android:layout_height="match_parent"
    android:gravity="center"
    android:layout_marginBottom="10dp">
<TextView
    android:id="@+id/tv_title"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="相冊"/>
</LinearLayout>

RecyclerView数据项layout_rv_item.xml

<?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">

    <LinearLayout
        android:id="@+id/layoutContent"
        android:background="#ffffff"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:id="@+id/img_icon"
            android:layout_width="match_parent"
            android:layout_height="100dp"
            android:src="@mipmap/ic_launcher"
            android:scaleType="fitXY" />

    </LinearLayout>
</LinearLayout>

第三步：编写Activity RecyclerViewActivity.java

package com.figo.study.activity;

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.StaggeredGridLayoutManager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;

import com.figo.study.R;
import com.figo.study.utils.CommonUtil;

import java.util.ArrayList;

public class RecyclerViewActivity extends Activity {
    RecyclerView mRecyclerView;
    PhotoAdapter mPhotoAdapter;
    ArrayList<Integer> imgs = null;
    int rvHead = 0;
    int rvItem = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recycler_view);
        mRecyclerView = (RecyclerView) findViewById(R.id.recyclerView_test);
        bindDataToRv();

    }

    private void bindDataToRv() {
        //测试，使用系统自带的图标
        imgs = new ArrayList<Integer>();
        for (int a = 0; a < 100; a++) {
            imgs.add(R.mipmap.ic_launcher);
        }
        //一、实现GridView效果，两列，第一列合并
        GridLayoutManager gridLayoutMgr = new GridLayoutManager(this, 2);
        //第一行，两列合并为一列，作为标题
        gridLayoutMgr.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {

            @Override
            public int getSpanSize(int position) {
                if (position == 0) {
                    return 2;
                }
                return 1;
            }
        });
        mRecyclerView.setLayoutManager(gridLayoutMgr);

        //二、实现ListView效果
        /*
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(linearLayoutManager);
        */


        //三、实现交错效果 (5,StaggeredGridLayoutManager.VERTICAL)表示显示5列，更多数据上下滑动
        // (5,StaggeredGridLayoutManager.HORIZONTAL) 表示显示5行，更多数据左右滑动

//        StaggeredGridLayoutManager staggeredGridLayoutManager=new StaggeredGridLayoutManager(5,StaggeredGridLayoutManager.HORIZONTAL);
//        mRecyclerView.setLayoutManager(staggeredGridLayoutManager);

        if (mPhotoAdapter == null) {
            mPhotoAdapter = new PhotoAdapter();
        }

        //数据绑定到RecyclerView
        mRecyclerView.setAdapter(mPhotoAdapter);
    }

    class PhotoAdapter extends RecyclerView.Adapter<PhotoAdapter.PhotoViewHolder> {

        @Override
        public PhotoViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            PhotoViewHolder holder = null;
            //根据view类型选择不同的加载项
            if (viewType == rvHead) {
                holder = new PhotoViewHolder(LayoutInflater.from(RecyclerViewActivity.this).inflate(R.layout.layout_rv_head, parent,
                        false), true);
            } else {
                holder = new PhotoViewHolder(LayoutInflater.from(RecyclerViewActivity.this).inflate(R.layout.layout_rv_item, parent,
                        false), false);
            }
            return holder;
        }

        @Override
        public void onBindViewHolder(PhotoViewHolder holder, int position) {
            if (position == 0) {
                holder.tvTitle.setText("This is Photo Album");
            } else {
                //设置RecyclerView横竖间距
                //Gridview效果
                LinearLayout.LayoutParams layoutParams = (LinearLayout.LayoutParams) holder.layoutContent.getLayoutParams();

                if (position % 2 == 0) {
                 layoutParams.setMargins(CommonUtil.dp2px(10, RecyclerViewActivity.this), 0, CommonUtil.dp2px(10, RecyclerViewActivity.this), CommonUtil.dp2px(10, RecyclerViewActivity.this));

                 } else {
                 layoutParams.setMargins(CommonUtil.dp2px(10, RecyclerViewActivity.this), 0, 0, CommonUtil.dp2px(10, RecyclerViewActivity.this));
                 }
                 holder.layoutContent.setVisibility(View.VISIBLE);

                //ListView效果
//                layoutParams.setMargins(0, 0, 0, CommonUtil.dp2px(10, RecyclerViewActivity.this));

                //设置图片
                holder.imgIcon.setImageResource(imgs.get(position - 1));//因为第一项是title

            }
        }
        //返回view类型
        @Override
        public int getItemViewType(int position) {
            if (position == 0) {
                return rvHead;
            } else {
                return rvItem;
            }
        }

        @Override
        public int getItemCount() {
            return imgs.size() + 1;//第一项是title，需要多加一项
        }

        class PhotoViewHolder extends RecyclerView.ViewHolder {

            ImageView imgIcon;
            TextView tvTitle;
            LinearLayout layoutContent;

            public PhotoViewHolder(View view, boolean isHead) {
                super(view);
                if (isHead) {
                    tvTitle = (TextView) view.findViewById(R.id.tv_title);
                } else {
                    layoutContent = (LinearLayout) view.findViewById(R.id.layoutContent);
                    imgIcon = (ImageView) view.findViewById(R.id.img_icon);
                }
            }
        }
    }
}