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"><ScrollViewandroid:layout_width="match_parent"android:layout_height="480dp"android:layout_gravity="center_horizontal|top"android:layout_margin="10dp"><LinearLayoutandroid:id="@+id/list_items"android:layout_width="match_parent"android:layout_height="wrap_content"android:orientation="vertical" /></ScrollView><LinearLayoutandroid:layout_width="match_parent"android:layout_height="wrap_content"android:gravity="center_horizontal"><Buttonandroid: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" /><Buttonandroid: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"><LinearLayoutandroid:id="@+id/item"android:layout_width="match_parent"android:layout_height="wrap_content"android:layout_marginTop="5dp"android:layout_marginBottom="5dp"android:orientation="horizontal"><LinearLayoutandroid: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"><ImageViewandroid: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><LinearLayoutandroid: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"><TextViewandroid: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" /><TextViewandroid: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><LinearLayoutandroid: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"><ImageViewandroid:id="@+id/item_edit"android:layout_width="48dp"android:layout_height="48dp"android:layout_marginRight="10dp"android:padding="10dp"android:src="@drawable/common_edit" /><ImageViewandroid: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 org.tao.hetools.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 org.tao.hetools.R;
import org.tao.hetools.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;@Overrideprotected 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layoutImageView 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layoutTextView 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layoutImageView 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;}
}
