Android ListView 应用解析

jopen 12年前

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：

Android ListView 应用解析

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;   }    }

Android ListView 应用解析

相关经验

目录