Android RecyclerView增加头部Header和尾部Footer，并实现Item分组

如图所示：

在Android的RecyclerView上实现增加若干头部Header和若干尾部Footer，关键是利用ViewType的类型，然后由本例的抽象类Item返回的类型加载不同的ViewHolder。
代码：

package app.zhangphil.exp; import android.graphics.Color; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.TextView; import java.util.ArrayList; public class MainActivity extends AppCompatActivity { private final int TYPE_HEADER = 0xa00; private final int TYPE_GROUP = 0xa01; private final int TYPE_CHILD = 0xa02; private final int TYPE_FOOTER = 0xa03; private RecyclerViewAdapter mAdapter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); RecyclerView recyclerView = findViewById(R.id.recycler_view); LinearLayoutManager layoutManage = new LinearLayoutManager(this); layoutManage.setOrientation(LinearLayoutManager.VERTICAL); recyclerView.setLayoutManager(layoutManage); mAdapter = new RecyclerViewAdapter(); recyclerView.setAdapter(mAdapter); String[] groupNames = {"A", "B", "C", "D", "E", "F", "G"}; for (int i = 0; i < groupNames.length; i++) { Group group = new Group(); group.id = i; group.title = groupNames[i]; mAdapter.addItem(group); int count = (int) (Math.random() * 10) % 3; for (int j = 0; j < count; j++) { Child child = new Child(); child.position = j; child.group = group; mAdapter.addItem(child); } } addHeader(); addFooter(); } private void addHeader() { for (int i = 0; i < 3; i++) { HeaderItem headerItem = new HeaderItem(); headerItem.id = i; mAdapter.addItem(i, headerItem); //增加一个头部，可以增加多个 } } private void addFooter() { for (int i = 0; i < 3; i++) { FooterItem footerItem = new FooterItem(); footerItem.id = i; mAdapter.addItem(footerItem); //增加一个尾部，可以增加多个 } } public class RecyclerViewAdapter extends RecyclerView.Adapter<ItemVH> { private ArrayList<Item> items; public RecyclerViewAdapter() { items = new ArrayList<>(); } @Override public ItemVH onCreateViewHolder(ViewGroup parent, int viewType) { View view; ItemVH itemVH = null; switch (viewType) { case TYPE_HEADER: view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false); itemVH = new HeaderVH(view); break; case TYPE_FOOTER: view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false); itemVH = new FooterVH(view); break; case TYPE_GROUP: view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_1, parent, false); itemVH = new GroupVH(view); break; case TYPE_CHILD: view = LayoutInflater.from(parent.getContext()).inflate(android.R.layout.simple_list_item_2, parent, false); itemVH = new ChildVH(view); break; } return itemVH; } @Override public void onBindViewHolder(ItemVH holder, int position) { Item item = items.get(position); switch (getItemViewType(position)) { case TYPE_HEADER: HeaderItem headerItem = (HeaderItem) items.get(position); HeaderVH headerVH = (HeaderVH) holder; headerVH.text.setText("第" + headerItem.id + "个头部"); break; case TYPE_FOOTER: FooterItem footerItem = (FooterItem) items.get(position); FooterVH footerVH = (FooterVH) holder; footerVH.text.setText("第" + footerItem.id + "个尾部"); break; case TYPE_GROUP: Group g = (Group) item; GroupVH groupVH = (GroupVH) holder; groupVH.text.setText(g.title); break; case TYPE_CHILD: Child c = (Child) item; ChildVH childVH = (ChildVH) holder; childVH.text1.setText(c.group.title); childVH.text2.setText(c.position + ""); break; } } @Override public int getItemCount() { return items.size(); } @Override public int getItemViewType(int position) { return items.get(position).getType(); } public void addItem(Item item) { items.add(item); } public void addItem(int position, Item item) { items.add(position, item); } } private class Group extends Item { public String title; @Override public int getType() { return TYPE_GROUP; } } private class Child extends Item { public Group group; @Override public int getType() { return TYPE_CHILD; } } private abstract class Item { public int position; public int id; public abstract int getType(); } private class FooterItem extends Item { @Override public int getType() { return TYPE_FOOTER; } } private class FooterVH extends ItemVH { public TextView text; public FooterVH(View itemView) { super(itemView); text = itemView.findViewById(android.R.id.text1); itemView.setBackgroundColor(Color.LTGRAY); } @Override public int getType() { return TYPE_FOOTER; } } private class HeaderItem extends Item { @Override public int getType() { return TYPE_HEADER; } } private class HeaderVH extends ItemVH { public TextView text; public HeaderVH(View itemView) { super(itemView); text = itemView.findViewById(android.R.id.text1); itemView.setBackgroundColor(Color.LTGRAY); } @Override public int getType() { return TYPE_HEADER; } } private class GroupVH extends ItemVH { public TextView text; public GroupVH(View itemView) { super(itemView); text = itemView.findViewById(android.R.id.text1); text.setBackgroundColor(Color.RED); } @Override public int getType() { return TYPE_GROUP; } } private class ChildVH extends ItemVH { public TextView text1; public TextView text2; public ChildVH(View itemView) { super(itemView); text1 = itemView.findViewById(android.R.id.text1); text2 = itemView.findViewById(android.R.id.text2); text1.setTextColor(Color.LTGRAY); text2.setTextColor(Color.BLUE); } @Override public int getType() { return TYPE_CHILD; } } private abstract class ItemVH extends RecyclerView.ViewHolder { public ItemVH(View itemView) { super(itemView); } public abstract int getType(); } }