Android ListView 應用解析

jopen 12年前發布 | 22K 次閱讀 Android Android開發移動開發

在android開發中ListView是比較常用的組件，它以列表的形式展示具體內容，并且能夠根據數據的長度自適應顯示。抽空把對ListView的使用做了整理，并寫了個小例子，如下圖。

列表的顯示需要三個元素：

1．ListVeiw 用來展示列表的View。

2．適配器用來把數據映射到ListView上的中介。

3．數據具體的將被映射的字符串，圖片，或者基本組件。

根據列表的適配器類型，列表分為三種，ArrayAdapter，SimpleAdapter和SimpleCursorAdapter

現在項目的結構如下圖所示：

Android ListView 應用解析

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如下圖所示：

<?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">數據庫應用</string>
    <string name="name">姓名</string>
    <string name="phone">電話</string>
</resources>

cn.roco.db.domain.Person代碼如下：

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);
    }
    /**
     * 添加記錄
     * @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() });
    }
    /**
     * 添加記錄
     * @param id 
     */
    @Override
    public void delete(Integer id) {
        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
        db.execSQL("delete from person where personid=?", new Object[] { id });
    }
    /**
     * 更新記錄
     * @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() });
    }
    /**
     * 查詢記錄
     * @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;
    }
    /**
     * 分頁獲取幾率
     * @param offset 跳過前面多少條記錄
     * @param maxResult 每頁獲取多少條記錄
     * @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;
    }

    /**
     * 獲取記錄總數
     * @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();
    }
    /**
     *配置一個響應事件類
     */
    private final class ItemClickListener implements OnItemClickListener{
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position,
                long id) {
            ListView lView=(ListView) parent;

            /**
             * 對應自定義適配器
             */
//          Person person= (Person) lView.getItemAtPosition(position);
//          Toast.makeText(getApplicationContext(), "id="+person.getId(), 1).show();
            /**
             * 對應游標適配器
             */
            Cursor cursor=(Cursor) lView.getItemAtPosition(position);
            int personid=cursor.getInt(cursor.getColumnIndex("_id"));
            Toast.makeText(getApplicationContext(), "id="+personid, 1).show();
        }
    }


    //使用自定義的適配器PersonAdapter
    private void showByPersonAdapter() {
        List<Person> persons=personService.getScrollData(0, 30);
        PersonAdapter adapter=new PersonAdapter(this, persons, R.layout.item);
        listView.setAdapter(adapter);
    }
    //使用游標適配器SimpleCursorAdapter
    private void showByCursor() {
        Cursor cursor = personService.getCursorScrollData(0, 30);

        /**
         * 注意該適配器中的cursor必須要包含 _id 字段
         * 解決方法：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);
    }
    //使用簡單適配器SimpleAdapter
    private void showByList() {
        List<Person> persons = personService.getScrollData(0, 30);

        /**
         * 將取出來的數據封裝到 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);
        }
        /**
         * 設置好適配器對應的關系
         */
        SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item,
                new String[] { "name", "phone" }, new int[] { R.id.name,
                        R.id.phone });
        listView.setAdapter(adapter);
    }
}

自定義的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; //綁定數據
    private int resouce ; //綁定的條目節目
    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
    //得到總的數量
    public int getCount() {
        return persons.size();   //數據總數
    }

    @Override
    //根據ListView位置返回View
    public Object getItem(int position) {
        return persons.get(position);
    }

    @Override
     //根據ListView位置得到List中的ID
    public long getItemId(int position) {
        return position;
    }

    @Override
     //根據位置得到View對象
    public View getView(int position, View convertView, ViewGroup parent) {
        TextView nameView=null;
        TextView phoneView=null;
        if (convertView==null) {
            convertView=inflater.inflate(resouce, null);//生成條目節目對象
             //得到條目中的子組件
            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;
        }
        //從list對象中為子組件賦值  實現數據綁定
        Person person= persons.get(position);
        nameView.setText(person.getName());
        phoneView.setText(person.getPhone());

        return convertView;
    }
    /**
     * 定義的緩存類
     */
    private final class ViewCache{
        public TextView nameView;
        public TextView phoneView;
    }

}

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