五步学会Android的ListView控件

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">使用Android的列表控件有几点要注意：
</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">一、要设计一个类来代表控件中的一行所要展示的数据，例如User类；</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">二、要设计一个layout来展示控件中的一行，例如user_item.xml；</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">三、要继承BaseAdapter类来包含列表控件中所有的数据列表，以及其展现方法；</span>

<span style="font-family:Arial, Helvetica, sans-serif;"><span style="background-color: rgb(255, 255, 255);">四、要在列表控件所在的Activity中加入设置代码。</span></span>

<span style="font-family:Arial, Helvetica, sans-serif;"><span style="background-color: rgb(255, 255, 255);">五、刷新列表控件时请使用BaseAdapter的notifyDataSetChanged方法和ListView类的invalidate方法。</span></span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">
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<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">具体使用分为以下五步：</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">
</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">1.在需要使用listview控件的layout中加入该控件；</span>

<span style="font-family: Arial, Helvetica, sans-serif; background-color: rgb(255, 255, 255);">2.listview控件的每一行对应一组数据，可以将这一组数据组成一个类，例如User类：</span>

public class User {
	private String id;
	private String name;
	private String phone;
	private String passwd;
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getPhone() {
		return phone;
	}
	public void setPhone(String phone) {
		this.phone = phone;
	}
	public String getPasswd() {
		return passwd;
	}
	public void setPasswd(String passwd) {
		this.passwd = passwd;
	}

}

3.为listview控件的每一行设计一个layout，这个layout就是为了展示User类的实例，例如：

<?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="horizontal" >

    <TextView
        android:id="@+id/id"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="id" />

    <TextView
        android:id="@+id/name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="name" />

    <TextView
        android:id="@+id/phone"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="phone" />

    <TextView
        android:id="@+id/passwd"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="passwd" />

</LinearLayout>

4.为该listview设计一个Adapter类，这个类包含了listview所要展示的对象列表，并在其getView(int, View, ViewGroup)方法中详细描述了如何展示每一行数据，例如：

package com.dumaisoft.kidscore.adapter;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.dumaisoft.kidscore.R;
import com.dumaisoft.kidscore.api.User;
import com.dumaisoft.kidscore.db.dao.UserDao;

/**
 * @author wxb
 * 用户的列表Adapter
 */
public class UserAdapter extends BaseAdapter {
	private Context context;
	private List<User> userlist;

	public UserAdapter(Context c){
		context = c;
		userlist = new ArrayList<User>();
		refreshData();
	}

	@Override
	public void notifyDataSetChanged() {
		// TODO Auto-generated method stub
		super.notifyDataSetChanged();
		refreshData();
	}

	/**
	 * 刷新用户列表，从数据库中重新读取
	 */
	public void refreshData(){
		userlist.clear();
		//列出每一个User,加入队列
		UserDao userdao = new UserDao(context);
		List<Map<String, String>> listmap = userdao.listUserMaps(null,null);
		for(int i =0;i<listmap.size();i++){
			Map<String,String > map = new HashMap<String, String>();
			map = listmap.get(i);
			User user = new User();
			user.setId(map.get("user_id"));
			user.setName(map.get("user_name"));
			user.setPhone(map.get("user_phone"));
			user.setPasswd(map.get("user_password"));
			userlist.add(user);
		}
	}

	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return userlist.size();
	}

	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return userlist.get(position);
	}

	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return position;
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		if (convertView == null) {
			convertView = LayoutInflater.from(context).inflate(
					R.layout.user_item, null);
		}
		User user = userlist.get(position);
		TextView id = (TextView) convertView.findViewById(R.id.id);
		id.setText(user.getId());
		TextView name = (TextView) convertView.findViewById(R.id.name);
		name.setText(user.getName());
		TextView phone = (TextView) convertView.findViewById(R.id.phone);
		phone.setText(user.getPhone());
		TextView passwd = (TextView) convertView.findViewById(R.id.passwd);
		passwd.setText(user.getPasswd());

		return convertView;
	}
}

5.在Activity类中添加listview的设置代码：

package com.dumaisoft.kidscore.activity;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.BaseAdapter;
import android.widget.ListView;

import com.dumaisoft.kidscore.R;
import com.dumaisoft.kidscore.adapter.UserAdapter;

public class UserActivity extends Activity {
	private UserActivity _c = this;
	private ListView listview;
	private UserAdapter useradapter;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
        setContentView(R.layout.user_activity);

        this.findViewById(R.id.btn_user_add).setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				startActivity(new Intent(_c,UserAddActivity.class));
			}
		});

        this.findViewById(R.id.btn_user_refresh).setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				((UserAdapter) listview.getAdapter()).notifyDataSetChanged();
				listview.invalidate();
			}
		});

        useradapter = new UserAdapter(_c);
        listview = (ListView) this.findViewById(R.id.listUser);
        listview.setAdapter(useradapter);
	}

	@Override
	protected void onDestroy() {
		// TODO Auto-generated method stub
		super.onDestroy();
	}
}