安卓动态添加View

在安卓应用中，有很多时候需要动态添加View。比如从后台获取商品列表，根据商品数量在页面渲染对应数量的条目，这时候就需要动态添加View。

1.动态添加View的方法

动态添加View有两种方法：

• 由代码生成子View：这种方式很繁琐，布局效果也不直观，而且很多属性设置不了（也可能是我没找对方法）；
• 从xml读取布局，然后动态设置信息：推荐该方式，配置xml时，可以直接看到效果，可设置的参数也更多。

接下来就用代码演示下如何使用这两种方式动态添加View。

注：子View也可以写在父View中，设置visible为GONE即可，在createItem最后添加一行item.setVisibility(View.VISIBLE);。

2. 代码实现

父View布局activity_list.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="match_parent"
    android:orientation="vertical">

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="480dp"
        android:layout_gravity="center_horizontal|top"
        android:layout_margin="10dp">

        <LinearLayout
            android:id="@+id/list_items"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical" />
    </ScrollView>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal">

        <Button
            android:id="@+id/list_switch_model"
            android:layout_width="100dp"
            android:layout_height="70dp"
            android:layout_gravity="center"
            android:layout_marginRight="20dp"
            android:text="Switch Model" />

        <Button
            android:id="@+id/list_add_item"
            android:layout_width="100dp"
            android:layout_height="70dp"
            android:layout_gravity="center"
            android:layout_marginLeft="20dp"
            android:text="Add Item" />
    </LinearLayout>
</LinearLayout>

子View布局activity_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="match_parent">

    <LinearLayout
            android:id="@+id/item"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginTop="5dp"
            android:layout_marginBottom="5dp"
            android:orientation="horizontal">

        <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_gravity="center_vertical"
                android:layout_marginLeft="10dp"
                android:layout_marginRight="10dp"
                android:gravity="right|center"
                android:orientation="horizontal">

            <ImageView
                    android:id="@+id/item_img"
                    android:layout_width="48dp"
                    android:layout_height="48dp"
                    android:layout_marginLeft="10dp"
                    android:layout_marginRight="10dp"
                    android:padding="10dp"
                    android:src="@drawable/common_item" />
        </LinearLayout>

        <LinearLayout
                android:layout_width="wrap_content"
                android:layout_height="match_parent"
                android:layout_gravity="center"
                android:layout_marginLeft="10dp"
                android:layout_marginRight="10dp"
                android:gravity="left|center"
                android:orientation="vertical">

            <TextView
                    android:id="@+id/item_index"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="index: item name"
                    android:textColor="@color/black"
                    android:textSize="6pt" />

            <TextView
                    android:id="@+id/item_name"
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:text="name: item name"
                    android:textColor="@color/black"
                    android:textSize="6pt" />
        </LinearLayout>

        <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_gravity="center_vertical"
                android:layout_marginRight="10dp"
                android:gravity="right|center"
                android:orientation="horizontal">

            <ImageView
                    android:id="@+id/item_edit"
                    android:layout_width="48dp"
                    android:layout_height="48dp"
                    android:layout_marginRight="10dp"
                    android:padding="10dp"
                    android:src="@drawable/common_edit" />

            <ImageView
                    android:id="@+id/item_delete"
                    android:layout_width="48dp"
                    android:layout_height="48dp"
                    android:layout_marginRight="10dp"
                    android:padding="10dp"
                    android:src="@drawable/common_delete" />
        </LinearLayout>
    </LinearLayout>
</LinearLayout>

activity类：

package com.example.study.activities;

import android.os.Bundle;
import android.util.Log;
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 androidx.activity.ComponentActivity;
import androidx.annotation.Nullable;

import com.example.study.R;
import com.example.study.entities.ItemInfo;

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

public class DynamicViewActivity extends ComponentActivity {
    private int index = 0;

    private boolean createViewFromXml = true;

    private List<ItemInfo> itemInfos = new ArrayList<>();

    private LinearLayout listItemsLayout;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_list);
        listItemsLayout = findViewById(R.id.list_items);
        initButton();
        initDynamicView();
    }

    private void initDynamicView() {
        if (listItemsLayout == null) {
            return;
        }
        listItemsLayout.removeAllViews();
        for (ItemInfo itemInfo : itemInfos) {
            listItemsLayout.addView(createViewFromXml ? createViewFromCode(itemInfo) : createViewFromCode(itemInfo));
        }
    }

    private void initButton() {
        findViewById(R.id.list_add_item).setOnClickListener(view -> {
            if (listItemsLayout == null) {
                return;
            }
            ItemInfo itemInfo = new ItemInfo(index, "name " + index, R.drawable.common_item);
            index++;
            itemInfos.add(itemInfo);
            listItemsLayout.addView(createViewFromXml ? createItem(itemInfo) : createViewFromCode(itemInfo));
        });
        findViewById(R.id.list_switch_model).setOnClickListener(view -> {
            itemInfos.clear();
            listItemsLayout.removeAllViews();
            createViewFromXml = !createViewFromXml;
        });
    }

    /**
     * 在代码中生成布局作为子view的布局
     *
     * @param itemInfo item信息
     * @return item view
     */
    private View createViewFromCode(ItemInfo itemInfo) {
        // item开头的图标layout
        ImageView itemImage = new ImageView(this);
        itemImage.setImageResource(R.drawable.common_item);
        itemImage.setMaxHeight(136);// 这个高度跟dp的换算，需要根据屏幕分辨率重新计算。下同
        itemImage.setMaxWidth(136);
        itemImage.setLeft(10);
        itemImage.setRight(10);
        itemImage.setPadding(5, 5, 5, 5);
        itemImage.setAdjustViewBounds(true);

        LinearLayout imageLayout = new LinearLayout(this);
        imageLayout.setOrientation(LinearLayout.HORIZONTAL);
        imageLayout.addView(itemImage);

        // item信息layout
        TextView index = new TextView(this);
        index.setText("index: " + itemInfo.getIndex());
        index.setTextSize(10);

        TextView name = new TextView(this);
        name.setText("name: " + itemInfo.getName());
        name.setTextSize(10);

        LinearLayout infoLayout = new LinearLayout(this);
        infoLayout.setOrientation(LinearLayout.VERTICAL);
        infoLayout.addView(index);
        infoLayout.addView(name);

        // 操作layout
        ImageView edit = new ImageView(this);
        edit.setImageResource(R.drawable.common_edit);
        edit.setMaxHeight(136);
        edit.setMaxWidth(136);
        edit.setAdjustViewBounds(true);


        ImageView delete = new ImageView(this);
        delete.setImageResource(R.drawable.common_delete);
        delete.setMaxHeight(136);
        delete.setMaxWidth(136);
        delete.setAdjustViewBounds(true);

        LinearLayout operateLayout = new LinearLayout(this);
        operateLayout.setOrientation(LinearLayout.HORIZONTAL);
        operateLayout.addView(edit);
        operateLayout.addView(delete);

        // 子view的信息
        LinearLayout layout = new LinearLayout(this);
        layout.setOrientation(LinearLayout.HORIZONTAL);
        layout.addView(imageLayout);
        layout.addView(infoLayout);
        layout.addView(operateLayout);

        edit.setOnClickListener(view -> {
            // todo 此处处理edit的点击事件
            Log.i("itemInfoList: ", itemInfos.toString());
        });

        delete.setOnClickListener(view -> {
            itemInfos.remove(itemInfo);
            listItemsLayout.removeView(layout);
        });

        return layout;
    }

    /**
     * 从xml文件获取布局作为子view的布局
     *
     * @param itemInfo item信息
     * @return item view
     */
    private View createItem(ItemInfo itemInfo) {
        LinearLayout inflate = (LinearLayout) LayoutInflater.from(this).inflate(R.layout.activity_item, null);
        LinearLayout item = inflate.findViewById(R.id.item);
        ((ImageView) item.findViewById(R.id.item_img)).setImageResource(itemInfo.getImageResourceId());
        ((TextView) item.findViewById(R.id.item_index)).setText("index: " + itemInfo.getIndex());
        ((TextView) item.findViewById(R.id.item_name)).setText("name: " + itemInfo.getName());
        item.findViewById(R.id.item_edit).setOnClickListener(view -> {
            // todo 此处处理edit的点击事件
            Log.i("itemInfoList: ", itemInfos.toString());
        });
        item.findViewById(R.id.item_delete).setOnClickListener(view -> {
            itemInfos.remove(itemInfo);
            listItemsLayout.removeView(item);
        });
        ((ViewGroup) item.getParent()).removeAllViews();
        return item;
    }
}

实体类：

package com.example.study.entities;

public class ItemInfo {
    private int index;

    private String name;

    private int imageResourceId;

    public ItemInfo(int index, String name, int imageResourceId) {
        this.index = index;
        this.name = name;
        this.imageResourceId = imageResourceId;
    }

    public int getIndex() {
        return index;
    }

    public void setIndex(int index) {
        this.index = index;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getImageResourceId() {
        return imageResourceId;
    }

    public void setImageResourceId(int imageResourceId) {
        this.imageResourceId = imageResourceId;
    }

    @Override
    public String toString() {
        return "ItemInfo{" +
                "index=" + index +
                ", name='" + name + '\'' +
                ", imageResourceId=" + imageResourceId +
                '}';
    }
}