适配器及适配器控件

适配器

什么是适配器：把数据转换为适配器控件所能使用的

SimpleAdapter（可以显示多个控件）
第一个参数填上下文对象
第二个为数据源（而且数据源必须是map对象组成的集合（list

SimpleAdapter adapter =new SimpleAdapter(content,data,resource,from,to);

ArrayAdapter（只能显示单一的TextView）
第一个参数填上下文对象
第二个参数填每个item的布局文件（注意ArrayAdapter的item布局文件只能是以TextView作为根节点的且只能匹配一个TextView）
第三个参数填item中的内容可以是数组或者集合

ArrayAdapter<String> adapter=new ArrayAdapter<>(content,resouce,data);

PagerAdapter
必须重写下面的四个方法
1. instantiateItem(ViewGroup, int)
2. destroyItem(ViewGroup, int, Object)
3. getCount()
4. isViewFromObject(View, Object)

private class ViewPagerAdapter extends PagerAdapter {  

        // 获取要滑动的控件的数量，在这里我们以滑动的广告栏为例，那么这里就应该是展示的广告图片的ImageView数量  
        @Override  
        public int getCount() {  
            return images.size();  
        }  

        // 来判断显示的是否是同一张图片，这里我们将两个参数相比较返回即可  
        @Override  
        public boolean isViewFromObject(View arg0, Object arg1) {  
            return arg0 == arg1;  
        }  

        // PagerAdapter只缓存三张要显示的图片，如果滑动的图片超出了缓存的范围，就会调用这个方法，将图片销毁  
        @Override  
        public void destroyItem(ViewGroup view, int position, Object object) {  
            view.removeView(images.get(position));  
        }  

        // 当要显示的图片可以进行缓存的时候，会调用这个方法进行显示图片的初始化，我们将要显示的ImageView加入到ViewGroup中，然后作为返回值返回即可  
        @Override  
        public Object instantiateItem(ViewGroup view, int position) {  
            view.addView(images.get(position));  
            return images.get(position);  
        }  
    }

BaseAdapter（自定义适配器，重点）

1.创建布局文件
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.cbt.learnbaseadapter.MainActivity">

    <ListView
        android:id="@+id/lv_main"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />
</RelativeLayout>

item.xml （ListView中每条信息的显示布局）

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:layout_width="match_parent"
              android:layout_height="wrap_content">
    <ImageView
        android:id="@+id/iv_image"
        android:src="@mipmap/ic_launcher"
        android:layout_width="60dp"
        android:layout_height="60dp"/>
    <TextView
        android:id="@+id/tv_title"
        android:layout_width="match_parent"
        android:layout_height="30dp"
        android:layout_toEndOf="@id/iv_image"
        android:text="Title"
        android:gravity="center"
        android:textSize="25sp"/>

    <TextView
        android:id="@+id/tv_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_toEndOf="@id/iv_image"
        android:layout_below="@id/tv_title"
        android:text="Content"
        android:textSize="20sp"/>
</RelativeLayout>

2.创建数据源
ItemBean.java

package com.example.lyj.myapplication;

/**
 * Created by caobotao on 15/12/20.
 */
public class ItemBean {
    public int itemImageResId;//图像资源ID
    public String itemTitle;//标题
    public String itemContent;//内容

    public ItemBean(int itemImageResId, String itemTitle, String itemContent) {
        this.itemImageResId = itemImageResId;
        this.itemTitle = itemTitle;
        this.itemContent = itemContent;
    }
}

MainActivity.java

package com.example.lyj.myapplication;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ListView;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    ListView mListView ;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        List<ItemBean> itemBeanList = new ArrayList<>();
        for (int i = 0;i < 20; i ++){
            itemBeanList.add(new ItemBean(R.mipmap.ic_launcher, "标题" + i, "内容" + i));
        }
        mListView = (ListView) findViewById(R.id.lv_main);
        //设置ListView的数据适配器
        mListView.setAdapter(new MyAdapter(this,itemBeanList));
    }
}

3.创建BaseAdapter

public View getView(int position, View convertView, ViewGroup parent) {//如果view未被实例化过，缓存池中没有对应的缓存
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.item,null);
        }
        /**
         * 找到item布局文件中对应的控件
         */
        ImageView imageView = (ImageView) convertView.findViewById(R.id.iv_image);
        TextView titleTextView = (TextView) convertView.findViewById(R.id.tv_title);
        TextView contentTextView = (TextView) convertView.findViewById(R.id.tv_content);

        //获取相应索引的ItemBean对象
        ItemBean bean = mList.get(position);
        /**
         * 设置控件的对应属性值
         */
        imageView.setImageResource(bean.itemImageResId);
        titleTextView.setText(bean.itemTitle);
        contentTextView.setText(bean.itemContent);
        return convertView;
    }

适配器控件

ListView (列表视图)
方法
addHeaderView(View v) 设置在ListView顶部
addFooterView(View v ) 设置在ListView底部
setAdapter(ListAdapter adapter) 设置ListView的适配器

package com.example.lyj.myapplication;

 import android.app.ListActivity;
 import android.os.Bundle;
 import android.view.View;
 import android.widget.ArrayAdapter;
 import android.widget.ListView;
 import android.widget.TextView;
 import android.widget.Toast;

 public class ListActivityDemo extends ListActivity {
    private String[] presidents={"北京","深圳","济南","广州","海南","香港","澳门"};

     @Override
     protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
         super.onCreate(savedInstanceState);
         ListView listview=getListView();
         //添加一个TextView作为表头
         TextView tvHeader=new TextView(ListActivityDemo.this);
         tvHeader.setText("城市列表头");
         listview.addHeaderView(tvHeader);
         //添加一个TextView作为表尾
         TextView tvFooter=new TextView(ListActivityDemo.this);
         tvFooter.setText("城市列表尾");
         listview.addFooterView(tvFooter);
         listview.setAdapter(new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,presidents));

     }
     @Override
    protected void onListItemClick(ListView parent, View view, int position, long id) {

         Toast.makeText(this, "You have selected "+presidents[position], Toast.LENGTH_SHORT).show();
     }
 }

效果图：
这里写图片描述
- GridView（网格视图）
Activity类

public class MainActivity extends Activity {
    private GridView gridView;
    private List<Map<String, Object>> dataList;
    private SimpleAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        gridView = (GridView) findViewById(R.id.gridview);
        //初始化数据
        initData();

        String[] from={"img","text"};

        int[] to={R.id.img,R.id.text};

        adapter=new SimpleAdapter(this, dataList, R.layout.gridview_item, from, to);

        gridView.setAdapter(adapter);

        gridView.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
                    long arg3) {
            AlertDialog.Builder builder= new AlertDialog.Builder(MainActivity.this);
            builder.setTitle("提示").setMessage(dataList.get(arg2).get("text").toString()).create().show();
            }
        });
    }

    void initData() {
        //图标
        int icno[] = { R.drawable.i1, R.drawable.i2, R.drawable.i3,
                R.drawable.i4, R.drawable.i5, R.drawable.i6, R.drawable.i7,
                R.drawable.i8, R.drawable.i9, R.drawable.i10, R.drawable.i11, R.drawable.i12 };
        //图标下的文字
        String name[]={"时钟","信号","宝箱","秒钟","大象","FF","记事本","书签","印象","商店","主题","迅雷"};
        dataList = new ArrayList<Map<String, Object>>();
        for (int i = 0; i <icno.length; i++) {
            Map<String, Object> map=new HashMap<String, Object>();
            map.put("img", icno[i]);
            map.put("text",name[i]);
            dataList.add(map);
        }
    }

}

主布局文件activity_main.xml

<LinearLayout 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="#000"
    tools:context="com.example.l7.MainActivity" >
    <GridView
        android:id="@+id/gridview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:columnWidth="80dp"
        android:stretchMode="spacingWidthUniform"
        android:numColumns="3" 
         />
</LinearLayout>

列表项布局gridview_item.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    android:orientation="vertical" >

    <ImageView
        android:id="@+id/img"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_marginTop="10dp" 
        android:src="@drawable/ic_launcher" />
    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="2dp" 
        android:layout_gravity="center"
        android:textColor="#FFF"
        android:text="文字"
        />

</LinearLayout>

效果图：
这里写图片描述
- ViewPager（用于实现页面间的切换）
1. ViewPager类直接继承了ViewGroup类，所有它是一个容器类，可以在其中添加其他的view类。
2. ViewPager类需要一个PagerAdapter适配器类给它提供数据。
3. ViewPager经常和Fragment一起使用，并且提供了专门的FragmentPagerAdapter和FragmentStatePagerAdapter类供Fragment中的ViewPager使用。

布局文件

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent">  

    <android.support.v4.view.ViewPager  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:id="@+id/vp_main_viewPage">  
    </android.support.v4.view.ViewPager>  
</LinearLayout>

RelativeLayout.xml页面

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical">  
    <TextView  
        android:background="#ff0000"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="我是Relative界面"  
        android:textSize="30sp"  
        android:gravity="center"/>  

</RelativeLayout>

LinearLayout.xml页面

<LinearLayout  
    xmlns:android="http://schemas.android.com/apk/res/android"  
    xmlns:app="http://schemas.android.com/apk/res-auto"  
    xmlns:tools="http://schemas.android.com/tools"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical"  
    tools:context="com.zking.administrator.myapplication.MainActivity">  

    <TextView  
        android:background="#00ff00"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="我是Linear界面"  
        android:textSize="30sp"  
        android:gravity="center"/>  
</LinearLayout>

FrameLayout.xml页面

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="match_parent"  
    android:layout_height="match_parent"  
    android:orientation="vertical">  
    <TextView  
        android:background="#0000ff"  
        android:layout_width="match_parent"  
        android:layout_height="match_parent"  
        android:text="我是Frame界面"  
        android:textSize="30sp"  
        android:gravity="center"/>  
</FrameLayout>

Java代码

import android.support.v4.view.PagerAdapter;  
import android.support.v4.view.ViewPager;  
import android.support.v7.app.AppCompatActivity;  
import android.os.Bundle;  
import android.view.View;  
import android.view.ViewGroup;  

import java.util.ArrayList;  
import java.util.List;  
/** 
 * Created by Administrator on 2017/6/13. 
 */  

public class HHActivity extends AppCompatActivity {  
    private  int Layouts[] = {R.layout.activity_main,R.layout.activity_frame,R.layout.activity_relative};  
    private ViewPager vp_main_viewPage;  
    private List<View> view_list = new ArrayList<>();  

    @Override  
    protected void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_hh);  
        vp_main_viewPage = (ViewPager) findViewById(R.id.vp_main_viewPage);  
        for (int i = 0; i <Layouts.length ; i++) {  
            View v = getLayoutInflater().inflate(Layouts[i],null);  
            view_list.add(v);  
        }  
        vp_main_viewPage.setAdapter(new MyAdapter());  

    }  
    class MyAdapter extends PagerAdapter{  

        @Override  
        public int getCount() {  
            return Layouts.length;  
        }  

        @Override  
        public boolean isViewFromObject(View view, Object object) {  
            return view==object;  
        }  

        @Override  
        public Object instantiateItem(ViewGroup container, int position) {  
            View v = view_list.get(position);  
            container.addView(v);  

            return v;  
        }  

        @Override  
        public void destroyItem(ViewGroup container, int position, Object object) {  
            View v = view_list.get(position);  
            container.removeView(v);  
        }  
    }  
}