Adapter

在android中有一组比较特别的组件，他们的使用有三部分来实现，M(数据模型)，V(视图)，C(控制)。以最典型的ListView为例，listView是用来显示数据的V（view），为ListView提供数据的数组或集合做为M(Model),而Adapter至关于C（Control）。由Adapter控制数据在控件上的显示。 今天，说说Adapter，固然，以ListView做为依托。

1、经常使用Adapter

一、Arrayadapter

二、SimpleAdapter

三、SimpleCursorAdapter

四、自定义Adapter

2、Adapter的使用方法

一、ArrayAdapter。

以程序说明在布局文件中，拖入一个Listview，以后在程序中实现数据加载

public class MainActivity extends Activity {
//定义Listview
private ListView lv;
//定义ArrayAdapter
private ArrayAdapter<String> adapter;
//定义要加载的数据
private String[] items={"oooo","uuuuu","mmmmm","vvvv"};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //findViewById方法从布局文件中获得ListView实例化Lv
        lv=(ListView) findViewById(R.id.lv1);
        //实例化adapter，经过系统会提供的方式
        adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,items);
        //为Listview绑定Adapter
        lv.setAdapter(adapter);
    }
                                                                                                          
}

程序执行效果：

二、SimpleAdapter。实例演示：

public class MainActivity extends Activity {
    private ListView lv;
    //定义一个adapter对象
    private SimpleAdapter adapter;
    //定义SimpleAdapter加载的数据
    private List<Map<String, Object>> list;
    private int[] imgid = { R.drawable.x1, R.drawable.x2, R.drawable.x3,
            R.drawable.x4, R.drawable.x5};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv=(ListView) findViewById(R.id.listView1);
        list=new ArrayList<Map<String,Object>>();
        Map<String,Object> map;
        //实例化list
        for(int i=0;i<imgid.length;i++){
            map=new HashMap<String, Object>();
            map.put("data", "ooo"+i);
            map.put("p_w_picpath", imgid[i]);
            list.add(map);
        }
        //实例化adapter
        adapter=new SimpleAdapter(this, list, R.layout.items,
                new String[]{"data","p_w_picpath"}, new int[]{R.id.textView1,R.id.p_w_picpathView1});
                //绑定adapter
        lv.setAdapter(adapter);
}
}

程序执行效果：

三、SimpleCursorAdapter，这个先不讲了，为何呀？由于我还不会呀，嘻嘻。之后会不上的。

四、自定义Adapter。当前面的几种Adapter没法知足须要时，咱们会考虑使用自定义Adapter。它须要继承BaseAdapter，而后至少要实现四个方法getCount(),getItem(),getItemId()及getView()方法。

实例演示：

自定义的Adapter：

public class MyAdapter extends BaseAdapter {
    private Context context;
    private String[] name;
    private String[] addr;
    private int[] imaids;
    public MyAdapter(Context context, String[] name, String[] addr, int[] imaids) {
        this.context = context;
        this.name = name;
        this.addr = addr;
        this.imaids = imaids;
    }
    @Override
    public int getCount() {
        return name.length;
    }
    @Override
    public Object getItem(int position) {
        return name[position];
    }
    @Override
    public long getItemId(int position) {
        return position;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = LayoutInflater.from(context).inflate(R.layout.items,
                    null);
            TextView tv1 = (TextView) convertView.findViewById(R.id.name);
            TextView tv2 = (TextView) convertView.findViewById(R.id.addr);
            ImageView iv = (ImageView) convertView
                    .findViewById(R.id.p_w_picpathView1);
            iv.setBackgroundResource(imaids[position]);
            CheckBox cb = (CheckBox) convertView.findViewById(R.id.checkBox1);
            tv1.setText(name[position]);
            tv2.setText(addr[position]);
            cb.setOnCheckedChangeListener(new OnCheckedChangeListener() {
                @Override
                public void onCheckedChanged(CompoundButton buttonView,
                        boolean isChecked) {
                    Toast.makeText(context, "dajiaho", Toast.LENGTH_LONG)
                            .show();
                }
            });
        } else {
            TextView tv1 = (TextView) convertView.findViewById(R.id.name);
            TextView tv2 = (TextView) convertView.findViewById(R.id.addr);
            CheckBox cb = (CheckBox) convertView.findViewById(R.id.checkBox1);
            ImageView iv = (ImageView) convertView
                    .findViewById(R.id.p_w_picpathView1);
            iv.setBackgroundResource(imaids[position]);
            tv1.setText(name[position]);
            tv2.setText(addr[position]);
        }
        return convertView;
    }
}

Activity代码：使用自定义的Adapter.

public class MainActivity extends Activity {
private ListView lv;
private MyAdapter adapter;
private String[] name={
        "金贤重","胡夏","林俊杰"
};
private String[] addr={
        "韩国.首尔","中国.青岛","中国.大连"
};
private int[] imaids={R.drawable.i2,R.drawable.hx,R.drawable.jj};
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        lv=(ListView) findViewById(R.id.listView1);
        adapter=new MyAdapter(this, name, addr,imaids);
        lv.setAdapter(adapter);
        lv.setOnItemClickListener(new OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                                         
                                         
            }
        });
    }
                             
}

程序执行效果：