在android开发中ListView是比较常用的组件，它以列表的形式展示具体内容，并且能够根据数据的长度自适应显示。抽空把对ListView的使用做了整理，并写了个小例子，如下图。
列表的显示需要三个元素：
1．ListVeiw 用来展示列表的View。
2．适配器 用来把数据映射到ListView上的中介。
3．数据 具体的将被映射的字符串，图片，或者基本组件。
根据列表的适配器类型，列表分为三种，ArrayAdapter，SimpleAdapter和SimpleCursorAdapter
现在项目的结构如下图所示：
main.xml如下所示：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="fill_parent" android:layout_height="fill_parent"> <LinearLayout android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="wrap_content"> <TextView android:text="@string/name" android:layout_width="120dp" android:layout_height="wrap_content" /> <TextView android:text="@string/phone" android:layout_width="fill_parent" android:layout_height="wrap_content" /> </LinearLayout> <ListView android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="@+id/listView" /> </LinearLayout>
item.xml如下图所示：
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal" android:layout_width="fill_parent" android:layout_height="fill_parent"> <TextView android:id="@+id/name" android:layout_width="120dp" android:layout_height="wrap_content"/> <TextView android:id="@+id/phone" android:layout_width="fill_parent" android:layout_height="wrap_content"/> </LinearLayout>
string.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello">Hello World, MainActivity!</string>
<string name="app_name">数据库应用</string>
<string name="name">姓名</string>
<string name="phone">电话</string>
</resources>
cn.roco.db.domain.Person代码如下：
package cn.roco.db.domain;
public class Person {
public Person(Integer id, String name, String phone) {
this.id = id;
this.name = name;
this.phone = phone;
}
public Person(String name, String phone) {
this.name = name;
this.phone = phone;
}
public Person() {
}
private Integer id;
private String name;
private String phone;
public Integer getId() {
return id;
}
public void setId(Integer 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;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return "Person[id="+id+",name="+name+",phone="+phone+"]";
}
}
package cn.roco.db.service;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
public class DBOpenHelper extends SQLiteOpenHelper {
public DBOpenHelper(Context context) {
super(context,"roco.db", null, 2);
}
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("CREATE TABLE person(personid integer primary key autoincrement,name varchar(20),phone varchar(20))");
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("ALTER TABLE person ADD phone VARCHAR(12) NULL");
}
}
package cn.roco.db.serice;
import java.util.List;
import cn.roco.db.domain.Person;
public interface IPersonService {
public void save(Person person);
public void delete(Integer id);
public void update(Person person);
public Person find(Integer id);
public List<Person> getScrollData(int offset,int maxResult);
public long getCount();
}
package cn.roco.db.serice.imp;
import java.util.ArrayList;
import java.util.List;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import cn.roco.db.domain.Person;
import cn.roco.db.serice.IPersonService;
import cn.roco.db.service.DBOpenHelper;
public class PersonServiceImp implements IPersonService {
private DBOpenHelper dbOpenHelper;
public PersonServiceImp(Context context) {
this.dbOpenHelper = new DBOpenHelper(context);
}
/**
* 添加记录
* @param person
*/
@Override
public void save(Person person) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("insert into person(name,phone) values(?,?)", new Object[] {
person.getName(), person.getPhone() });
}
/**
* 添加记录
* @param id
*/
@Override
public void delete(Integer id) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL("delete from person where personid=?", new Object[] { id });
}
/**
* 更新记录
* @param person
*/
@Override
public void update(Person person) {
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.execSQL(
"update person set name=?,phone=? where personid=?",
new Object[] { person.getName(), person.getPhone(),
person.getId() });
}
/**
* 查询记录
* @param id
*/
@Override
public Person find(Integer id) {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery(
"select personid,name,phone from person where personid=?",
new String[] { id.toString() });
if (cursor.moveToFirst()) {
int personid = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
return new Person(personid, name, phone);
}
cursor.close();
return null;
}
/**
* 分页获取几率
* @param offset 跳过前面多少条记录
* @param maxResult 每页获取多少条记录
* @return
*/
@Override
public List<Person> getScrollData(int offset, int maxResult) {
List<Person> persons = new ArrayList<Person>();
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db
.rawQuery(
"select * from person order by personid asc limit ?,?",
new String[] { String.valueOf(offset),
String.valueOf(maxResult) });
while (cursor.moveToNext()) {
int personid = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
String phone = cursor.getString(cursor.getColumnIndex("phone"));
persons.add(new Person(personid, name, phone));
}
cursor.close();
return persons;
}
public Cursor getCursorScrollData(int offset, int maxResult) {
List<Person> persons = new ArrayList<Person>();
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db
.rawQuery(
"select personid as _id, name, phone from person order by personid asc limit ?,?",
new String[] { String.valueOf(offset),
String.valueOf(maxResult) });
return cursor;
}
/**
* 获取记录总数
* @return
*/
@Override
public long getCount() {
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.rawQuery("select count(*) from person ", null);
cursor.moveToFirst();
long result = cursor.getLong(0);
cursor.close();
return result;
}
}
MainActivity
package cn.roco.db;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import cn.roco.db.adapter.PersonAdapter;
import cn.roco.db.domain.Person;
import cn.roco.db.serice.imp.PersonServiceImp;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.SimpleCursorAdapter;
import android.widget.Toast;
public class MainActivity extends Activity {
private ListView listView;
private PersonServiceImp personService;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
personService = new PersonServiceImp(this);
listView = (ListView) this.findViewById(R.id.listView);
listView.setOnItemClickListener(new ItemClickListener());
showByCursor();
// showByList();
// showByPersonAdapter();
}
/**
*配置一个响应事件类
*/
private final class ItemClickListener implements OnItemClickListener{
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
ListView lView=(ListView) parent;
/**
* 对应自定义适配器
*/
// Person person= (Person) lView.getItemAtPosition(position);
// Toast.makeText(getApplicationContext(), "id="+person.getId(), 1).show();
/**
* 对应游标适配器
*/
Cursor cursor=(Cursor) lView.getItemAtPosition(position);
int personid=cursor.getInt(cursor.getColumnIndex("_id"));
Toast.makeText(getApplicationContext(), "id="+personid, 1).show();
}
}
//使用自定义的适配器PersonAdapter
private void showByPersonAdapter() {
List<Person> persons=personService.getScrollData(0, 30);
PersonAdapter adapter=new PersonAdapter(this, persons, R.layout.item);
listView.setAdapter(adapter);
}
//使用游标适配器SimpleCursorAdapter
private void showByCursor() {
Cursor cursor = personService.getCursorScrollData(0, 30);
/**
* 注意该适配器中的cursor必须要包含 _id 字段
* 解决方法：select personid as _id .....
*/
SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,
R.layout.item, cursor, new String[] { "name", "phone" },
new int[] { R.id.name, R.id.phone });
listView.setAdapter(adapter);
}
//使用简单适配器SimpleAdapter
private void showByList() {
List<Person> persons = personService.getScrollData(0, 30);
/**
* 将取出来的数据封装到 List<HashMap<String, Object>> 中
*/
List<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
for (Person person : persons) {
HashMap<String, Object> item = new HashMap<String, Object>();
item.put("name", person.getName());
item.put("phone", person.getPhone());
item.put("id", person.getId());
data.add(item);
}
/**
* 设置好适配器对应的关系
*/
SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item,
new String[] { "name", "phone" }, new int[] { R.id.name,
R.id.phone });
listView.setAdapter(adapter);
}
}
自定义的Adapter
package cn.roco.db.adapter;
import java.util.List;
import cn.roco.db.R;
import cn.roco.db.domain.Person;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;
public class PersonAdapter extends BaseAdapter {
private List<Person> persons; //绑定数据
private int resouce ; //绑定的条目节目
private LayoutInflater inflater;
public PersonAdapter(Context context, List<Person> persons,int resouce) {
this.persons=persons;
this.resouce=resouce;
inflater= (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}
@Override
//得到总的数量
public int getCount() {
return persons.size(); //数据总数
}
@Override
//根据ListView位置返回View
public Object getItem(int position) {
return persons.get(position);
}
@Override
//根据ListView位置得到List中的ID
public long getItemId(int position) {
return position;
}
@Override
//根据位置得到View对象
public View getView(int position, View convertView, ViewGroup parent) {
TextView nameView=null;
TextView phoneView=null;
if (convertView==null) {
convertView=inflater.inflate(resouce, null);//生成条目节目对象
//得到条目中的子组件
nameView=(TextView) convertView.findViewById(R.id.name);
phoneView= (TextView) convertView.findViewById(R.id.phone);
ViewCache cache=new ViewCache();
cache.nameView=nameView;
cache.phoneView=phoneView;
convertView.setTag(cache);
}else{
ViewCache cache=(ViewCache) convertView.getTag();
nameView=cache.nameView;
phoneView=cache.phoneView;
}
//从list对象中为子组件赋值 实现数据绑定
Person person= persons.get(position);
nameView.setText(person.getName());
phoneView.setText(person.getPhone());
return convertView;
}
/**
* 定义的缓存类
*/
private final class ViewCache{
public TextView nameView;
public TextView phoneView;
}
}
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作者：欧阳鹏 欢迎转载，与人分享是进步的源泉！
转载请保留原文地址：http://blog.csdn.net/ouyang_peng
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时间： 2024-11-08 18:28:20