前言：GridView可用于展示多行多列的统一格式数据，但本身没有多选操作。现通过一系列代码实现GridView的长按多选操作，可以先看一个示例图。 
以下是实现该功能的主要代码：
MainActivity.java
package com.mygridview;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.GridView;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.HashMap;
public class MainActivity extends AppCompatActivity implements View.OnClickListener, AdapterView.OnItemClickListener, AdapterView.OnItemLongClickListener {
private ActionBar actionBar;
private Button btnCancel, btnDel, btnSelectAll, btnClear;
private RelativeLayout headerLayout;
private TextView numText;
private GridView gridView;
private ArrayList<HashMap<String, Object>> items; //每一个item
private ArrayList<Boolean> selectItems; //用于存储已选中项目的位置
private MyAdapter adapter;
private boolean isState;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
}
private void initView() {
actionBar = getSupportActionBar();
actionBar.setTitle("GridView");
numText = (TextView) findViewById(R.id.number);
btnCancel = (Button) findViewById(R.id.btn_cancel);
btnDel = (Button) findViewById(R.id.btn_del);
btnSelectAll = (Button) findViewById(R.id.btn_select_all);
btnClear = (Button) findViewById(R.id.btn_clear);
btnCancel.setOnClickListener(this);
btnDel.setOnClickListener(this);
btnSelectAll.setOnClickListener(this);
btnClear.setOnClickListener(this);
headerLayout = (RelativeLayout) findViewById(R.id.header);
gridView = (GridView) findViewById(R.id.grid_view);
items = new ArrayList<>();
selectItems = new ArrayList<>();
for (int i = 0; i < 20; i++) {
HashMap<String, Object> item = new HashMap<>();
item.put("image", R.drawable.image);
items.add(item);
}
adapter = new MyAdapter(this, items, R.layout.image, new String[]{"image"}, new int[]{R.id.my_image});
gridView.setAdapter(adapter);
gridView.setOnItemClickListener(this);
gridView.setOnItemLongClickListener(this);
}
public ArrayList<Boolean> getSelectItems() {
return selectItems;
}
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_cancel :
selectItems.clear();
numText.setText("已选择1项");
adapter.setIsState(false);
setState(false);
break;
case R.id.btn_clear :
setSelectAll(false);
break;
case R.id.btn_select_all:
setSelectAll(true);
break;
case R.id.btn_del:
delSelections();
break;
}
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
if (isState) {
CheckBox checkBox = (CheckBox) view.findViewById(R.id.check_box);
if (checkBox.isChecked()) {
checkBox.setChecked(false);
selectItems.set(position, false);
} else {
checkBox.setChecked(true);
selectItems.set(position, true);
}
adapter.notifyDataSetChanged();
setSelectNum();
}
}
@Override
public boolean onItemLongClick(AdapterView<?> parent, View view, int position, long id) {
if (!isState) {
selectItems = new ArrayList<>();
for (int i = 0; i < items.size(); i++) {
selectItems.add(false);
}
CheckBox box = (CheckBox) view.findViewById(R.id.check_box);
box.setChecked(true);
selectItems.set(position, true);
setState(true);
adapter.setIsState(true);
setSelectNum();
}
return false;
}
//设置当前状态 是否在多选模式
private void setState(boolean b) {
isState = b;
if (b) {
headerLayout.setVisibility(View.VISIBLE);
btnDel.setVisibility(View.VISIBLE);
actionBar.hide();
} else {
headerLayout.setVisibility(View.GONE);
btnDel.setVisibility(View.GONE);
actionBar.show();
}
}
//显示已选项数目
private void setSelectNum() {
int num = 0;
for (Boolean b : selectItems) {
if (b)
num ++;
}
numText.setText("已选择" + num + "项");
}
//全选
private void setSelectAll(boolean b) {
for (int i = 0; i < selectItems.size(); i++) {
selectItems.set(i, b);
adapter.notifyDataSetChanged();
setSelectNum();
}
btnSelectAll.setVisibility(b? View.GONE : View.VISIBLE);
btnClear.setVisibility(b ? View.VISIBLE : View.GONE);
}
//删除
private void delSelections() {
AlertDialog.Builder builder = new AlertDialog.Builder(this);
if (!selectItems.contains(true)) {
builder.setTitle("提示").setMessage("当前未选中项目").setPositiveButton("确认", null).create().show();
} else {
builder.setTitle("提示");
builder.setMessage("确认删除所选项目？");
builder.setPositiveButton("确认", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
for (int i = 0; i < items.size(); i++) {
if (selectItems.get(i)) {
items.set(i, null);
}
}
while (items.contains(null)) {
items.remove(null);
}
selectItems = new ArrayList<>();
for (int i = 0; i < items.size(); i++) {
selectItems.add(false);
}
adapter.setData(items);
adapter.notifyDataSetChanged();
if (items.size() == 0) {
adapter.setIsState(false);
setState(false);
return;
}
}
});
builder.setNegativeButton("取消", null);
builder.create().show();
}
}
private long mExitTime;
public boolean onKeyDown(int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_BACK) {
if (isState) {
selectItems.clear();
numText.setText("已选择1项");
adapter.setIsState(false);
setState(false);
return true;
} else {
if ((System.currentTimeMillis() - mExitTime) > 2000) {
Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
mExitTime = System.currentTimeMillis();
}
else finish();
return true;
}
}
return super.onKeyDown(keyCode, event);
}
}
设配器Adapter
package com.mygridview;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.CheckBox;
import android.widget.SimpleAdapter;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
public class MyAdapter extends SimpleAdapter {
private List<? extends Map<String, ?>> data;
private int resourse;
private Context context;
private LayoutInflater inflater;
private boolean isState = false;
public MyAdapter(Context context, List<? extends Map<String, ?>> data, int resource, String[] from, int[] to) {
super(context, data, resource, from, to);
inflater = LayoutInflater.from(context);
this.resourse = resource;
this.data = data;
this.context = context;
}
public void setData(List<? extends Map<String, ?>> data) {
this.data = data;
}
public void setIsState(boolean isState) {
this.isState = isState;
notifyDataSetChanged();
}
@Override
public int getCount() {
return data.size();
}
@Override
public Object getItem(int position) {
return data.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ArrayList<Boolean> list = ((MainActivity) context).getSelectItems();
convertView = inflater.inflate(resourse ,null);
CheckBox checkBox = (CheckBox) convertView.findViewById(R.id.check_box);
checkBox.setVisibility(isState? View.VISIBLE : View.GONE);
if (list.size() != 0)
checkBox.setChecked(list.get(position));
return super.getView(position, convertView, parent);
}
}主页面布局 activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context="com.mygridview.MainActivity">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:id="@+id/header"
android:visibility="gone"
android:background="@color/colorPrimary"
>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/btn_cancel"
android:background="@android:color/transparent"
android:text="取消"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="已选择1项"
android:layout_centerVertical="true"
android:layout_centerInParent="true"
android:id="@+id/number"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="全选"
android:background="@android:color/transparent"
android:id="@+id/btn_select_all"
android:layout_alignParentEnd="true"
/>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="清除"
android:background="@android:color/transparent"
android:id="@+id/btn_clear"
android:visibility="gone"
android:layout_alignParentEnd="true"
/>
</RelativeLayout>
<GridView
android:layout_below="@+id/header"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:numColumns="3"
android:id="@+id/grid_view"
android:verticalSpacing="10dp"
android:horizontalSpacing="10dp"
android:layout_above="@+id/btn_del"
>
</GridView>
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="删除"
android:id="@+id/btn_del"
android:visibility="gone"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true" />
</RelativeLayout>
每个item的布局 image.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="wrap_content"
android:layout_height="match_parent"
android:descendantFocusability="blocksDescendants"
>
<RelativeLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<ImageView
android:layout_width="120dp"
android:layout_height="150dp"
android:src="@drawable/image"
android:scaleType="centerCrop"
android:id="@+id/my_image"
/>
<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/check_box"
android:visibility="gone"
android:layout_alignParentTop="true"
android:layout_alignRight="@+id/my_image"
android:layout_alignEnd="@+id/my_image" />
</RelativeLayout>
</LinearLayout>问题总结：
1.当进入多选模式时点击图片CheckBox不会选中。
答：由于图片和多选框组成的view的点击事件与多选框的点击事件冲突，所以无法选中，可以在xml的根布局中加入android:descendantFocusability=”blocksDescendants”即可解决。