黎活明8天快速掌握android视频教程--19_采用ListView实现数据列表显示-白红宇

黎活明8天快速掌握android视频教程--19_采用ListView实现数据列表显示

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发布时间：2019-06-18

本文共 19081 字，大约阅读时间需要 63 分钟。

1、首先整个程序也是采用mvc的框架

DbOpenHelper 类

package dB;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.widget.Toast;public class DbOpenHelper extends SQLiteOpenHelper{    public DbOpenHelper(Context context) {        super(context, "wy.db", null, 2);    }    @Override    public void onCreate(SQLiteDatabase db)    {     db.execSQL("CREATE TABLE person(personid integer primary key autoincrement, name varchar(20), phone VARCHAR(12) NULL)");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    }}

数据库操作接口类：

我们可以采用下面的两种方式对数据库进行操作：

方式1：

package service;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import java.util.ArrayList;import java.util.List;import dB.DbOpenHelper;import domain.Person;public class OtherPersonService {private DbOpenHelper dbOpenHelper;    public OtherPersonService(Context context) {        this.dbOpenHelper = new DbOpenHelper(context);    }    public void save(Person person){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        ContentValues values = new ContentValues();        values.put("name",person.getName());        values.put("phone",person.getPhone());        db.insert("person",null,values);    }    /**     * 删除记录     * @param name 记录ID     */    public void delete(String name,String phone){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();       /* db.execSQL("delete from person where name=? and phone=?", new Object[]{name,phone});*/        db.delete("person", "name=? and phone= ?", new String[]{name ,phone});    }    /**     * 更新记录     * @param person     */    public void update(Person person,String name,String phone){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();       /* db.execSQL("update person set name=?,phone=? where name=? and phone=?",                new Object[]{person.getName(), person.getPhone(),name,phone});*/        ContentValues values = new ContentValues();        values.put("name",person.getName());        values.put("phone",person.getPhone());        db.update("person",values,"name=? and phone=?",new String[]{name ,phone});    }    /**     * 查询记录     * @param name 记录ID     * @return     */    public Person find(String name,String phone){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();       /* Cursor cursor = db.rawQuery("select * from person where name=? and phone = ?", new String[]{name, phone});*/        Cursor  cursor = db.query("person",null,"name=? and phone=?",new String[]{name,phone},null,null,null);        if(cursor.moveToNext()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            String name1 = cursor.getString(cursor.getColumnIndex("name"));            String phone1 = cursor.getString(cursor.getColumnIndex("phone"));            return new Person( name1, phone1);        }        cursor.close();        return null;    }    /**     * 分页获取记录     * @param offset 跳过前面多少条记录     * @param maxResult 每页获取多少条记录     * @return     */    public List
     
       getScrollData(int offset, int maxResult){        List
      
        persons = new ArrayList
       
        ();        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();       /* Cursor cursor = db.rawQuery("select * from person order by personid asc limit ?,?",*/        Cursor  cursor = db.query("person",null,null,null,null,null,"personid asc",offset+ ","+ maxResult);        while(cursor.moveToNext()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            /*这里也可以写成            *   String name = cursor.getString(1);            String phone = cursor.getString(2);             默认的表自带的id字段为0 ，name为第一个字段所有为1 ，phone为第二个字段为2*/            String name = cursor.getString(cursor.getColumnIndex("name"));            String phone = cursor.getString(cursor.getColumnIndex("phone"));            persons.add(new Person( name, phone));        }        cursor.close();        return persons;    }    /**     * 获取记录总数     * @return     */    public long getCount(){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        /*Cursor cursor = db.rawQuery("select count(*) from person", null);*/        Cursor cursor = db.query("person", new String[]{"count(*)"}, null, null, null, null, null);        cursor.moveToFirst();        long result = cursor.getLong(0);//统计之后只有一个默认的字段，所以为0        cursor.close();        return result;    }}

直接采用query的方式：

方式二：

package service;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.util.Log;import java.util.ArrayList;import java.util.List;import dB.DbOpenHelper;import domain.Person;public class PersonService {private DbOpenHelper dbOpenHelper;    public PersonService(Context context) {        this.dbOpenHelper = new DbOpenHelper(context);    }    public void save(Person person){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.execSQL("insert into person(name, phone) values(?,?)",                new Object[]{person.getName(), person.getPhone()});    }    /**     * 删除记录     * @param name 记录ID     */    public void delete(String name,String phone){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.execSQL("delete from person where name=? and phone=?", new Object[]{name,phone});    }    /**     * 更新记录     * @param person     */    public void update(Person person,String name,String phone){        SQLiteDatabase db = dbOpenHelper.getWritableDatabase();        db.execSQL("update person set name=?,phone=? where name=? and phone=?",                new Object[]{person.getName(), person.getPhone(),name,phone});    }    /**     * 查询记录     * @param name 记录ID     * @return     */    public Person find(String name,String phone){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.rawQuery("select * from person where name=? and phone = ?", new String[]{name,phone});        if(cursor.moveToNext()){            int personid = cursor.getInt(cursor.getColumnIndex("personid"));            String name1 = cursor.getString(cursor.getColumnIndex("name"));            String phone1 = cursor.getString(cursor.getColumnIndex("phone"));            return new Person( name1, phone1);        }        cursor.close();        return null;    }    /**     * 分页获取记录     * @param offset 跳过前面多少条记录     * @param maxResult 每页获取多少条记录     * @return     */    public List
     
       getScrollData(int offset, int maxResult){        List
      
        persons = new ArrayList
       
        ();        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"));            /*这里也可以写成            *   String name = cursor.getString(1);            String phone = cursor.getString(2);             默认的表自带的id字段为0 ，name为第一个字段所有为1 ，phone为第二个字段为2*/            String name = cursor.getString(cursor.getColumnIndex("name"));            String phone = cursor.getString(cursor.getColumnIndex("phone"));            persons.add(new Person( name, phone));        }        cursor.close();        return persons;    }    /**     * 获取记录总数     * @return     */    public long getCount(){        SQLiteDatabase db = dbOpenHelper.getReadableDatabase();        Cursor cursor = db.rawQuery("select count(*) from person", null);        cursor.moveToFirst();        long result = cursor.getLong(0);//统计之后只有一个默认的字段，所以为0        cursor.close();        return result;    }    /*使用 SimpleCursorAdapter加装数据的时候，创建的数据库表的主键必须是_id,    * 这里我们使用personid as _id，将创建表的主键personid变成_id    * 返回cursor对象的时候，千万不能关闭cursor对象：cursor.close();*/    public Cursor getScrollCursorData(int offset, int maxResult){        List
        
          persons = new ArrayList
         
          ();        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;//返回cursor对象之前，千万不能关闭cursor对象cursor.close();    }}

在正式的代码中建议使用方式2的这种方式进行操作：

Person对象

package domain;public class Person{    private String name;    private String phone;    @Override    public String toString() {        return "Person{" +                "name='" + name + '\'' +                ", phone='" + phone + '\'' +                '}';    }    public Person(String name, String phone) {        this.name = name;        this.phone = phone;    }    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;    }}

要显示数据需要新建立一个adapter对象PersonAdapter

package adapter;import android.content.Context;import android.database.Cursor;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;import java.util.List;import domain.Person;import test.weiyuan.sqllite1.R;public class PersonAdapter  extends BaseAdapter{    private List
     
       persons;//要绑定的数据    private int resource;//布局文件资源    private Context context;//activity的上下文    public PersonAdapter(List
      
        persons, int resource, Context context) {        this.persons = persons;        this.resource = resource;        this.context = context;    }    //绑定数据的数据大小    @Override    public int getCount() {        return persons.size();    }//显示数据在绑定数据List
       
        的位置,getItemAtPosition(position)来获得我们单击的item中的数据的时候，调用的就是    //getItem(int position)函数来获得我们的数据    @Override    public Object getItem(int position)    {        return persons.get(position);    }//这个可以不管    @Override    public long getItemId(int position) {        return position;    }//让数据如何在listview中显示出来    @Override    public View getView(int position, View convertView, ViewGroup parent) {       /* if(convertView==null)        {          convertView = (View)LayoutInflater.from(context).inflate(resource,null);        }        Person person = persons.get(position);        TextView name = (TextView)convertView.findViewById(R.id.name);        TextView phone = (TextView)convertView.findViewById(R.id.phone);        name.setText(person.getName());        phone.setText(person.getPhone());*/        //上面的代码不够优化，我们可以使用一个优化的方法给以解决        TextView name = null;        TextView phone = null;        if(convertView==null)        {            convertView = (View)LayoutInflater.from(context).inflate(resource,null);             name = (TextView)convertView.findViewById(R.id.name);              phone = (TextView)convertView.findViewById(R.id.phone);            ViewCache cache = new ViewCache();            cache.name = name;            cache.phone = phone;            convertView.setTag(cache);        }        else        {            ViewCache cache = (ViewCache)convertView.getTag();            name = cache.name;            phone =cache.phone;        }        Person person = persons.get(position);        name.setText(person.getName());        phone.setText(person.getPhone());        return convertView;    }    private  final class  ViewCache    {        public  TextView name;        public  TextView phone;    }}

接下来看看activity的代码如下：

显示数据的时候采用了下面的三种方式来加载数据的显示：

1、使用下面的三种方式类进行显示

package test.weiyuan.sqllite1;import android.app.Activity;import android.database.Cursor;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.AdapterView;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.SimpleCursorAdapter;import android.widget.Toast;import java.util.ArrayList;import java.util.Collection;import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Set;import adapter.PersonAdapter;import dB.DbOpenHelper;import domain.Person;import service.PersonService;public class MyActivity extends Activity {    final static String TAG = "weiyuan";    private ListView listView;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_my);        listView = (ListView) this.findViewById(R.id.listView);         /*创建数据库*/        DbOpenHelper dbOpenHelper = new DbOpenHelper(MyActivity.this);        dbOpenHelper.getWritableDatabase();        /*在数据库中保存数据*/        PersonService service = new PersonService(MyActivity.this);        for (int i = 0; i < 20; i++) {            service.save(new Person("weiyuan" + i, "12345" + i));        }        Log.i(TAG, "数据保存成功");        //拖动Listview的时候顶部和底部不会出现阴影        listView.setOverScrollMode(View.OVER_SCROLL_NEVER);        listView.setCacheColorHint(0);        //在Listview中显示数据        show();       // show1();        //show2();        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {            @Override            public void onItemClick(AdapterView
      parent, View view, int position, long id) {               /* //调用SimpleCursorAdapter方式的时候，使用getItemAtPosition(position)函数返回List的数据集合中的元素是Cursor类型               //parent就是我们单击的Listview                ListView listView1 = (ListView)parent;               Cursor cursor = (Cursor)listView1.getItemAtPosition(position);                String name = cursor.getString(cursor.getColumnIndex("name"));                String phone  =cursor.getString(cursor.getColumnIndex("phone"));                Toast.makeText(MyActivity.this,name+","+phone,Toast.LENGTH_LONG).show();*/         /*    *//*  调用自定义适配器的时候，getItemAtPosition(position)函数返回的是Person类型，                getItemAtPosition(position)的实现是通过调用BaseAdapter类中的                @Override                public Object getItem(int position)                {                    return persons.get(position);                }                来实现的*//*                ListView listView1 = (ListView)parent;                Person person= (Person)listView1.getItemAtPosition(position);                Toast.makeText(MyActivity.this,person.getName()+","+person.getPhone(),Toast.LENGTH_SHORT).show();*/                //调用SimpleAdapter来显示ListView的数据，getItemAtPosition(position)返回的是HashMap的数据                ListView listView1 = (ListView)parent;                HashMap
     
       map= (HashMap
      
       )listView1.getItemAtPosition(position);                String name =map.get("name");                String phone = map.get("phone");                Toast.makeText(MyActivity.this,name+","+phone,Toast.LENGTH_LONG).show();             /*   总结：通过适配器加载数据的时候：getItemAtPosition(position)返回的就是适配器加载的数据集合中元素的类型，是集合中元素                        的类型，我们来看一下：比如是SimpleAdapter来显示ListView的数据：                SimpleAdapter simpleAdapter = new SimpleAdapter(this, datalist, R.layout.item,                        new String[]{"name", "phone"}, new int[]{R.id.name, R.id.phone});                其中datalist就是我们加载的数据集合，datalist是List
       
        
         >类型，该集合中的元素就是Map
         
          类型；                同理通过 SimpleCursorAdapter加载数据：                SimpleCursorAdapter simplecursoradapter = new SimpleCursorAdapter(this, R.layout.item,                        cursor, new String[]{"name", "phone"}, new int[]{R.id.name, R.id.phone});                其中cursor就是加载的数据集合，该集合中的元素也是cursor类型。*/            }        });    }/*方法三：使用自定义的适配器来加载数据*/    private void show2()    {        List
          
            persons = new ArrayList
           
            (); PersonService service = new PersonService(MyActivity.this); persons = service.getScrollData(0, 20); PersonAdapter personAdapter = new PersonAdapter(persons,R.layout.item,this); listView.setAdapter(personAdapter); } /*通过 SimpleCursorAdapter加装游标适配器来显示数据 * 这里是 new String[]{"name", "phone"}对应的是数据库表中的字段名称*/ private void show1() { PersonService service = new PersonService(MyActivity.this); Cursor cursor = service.getScrollCursorData(0, 20); SimpleCursorAdapter simplecursoradapter = new SimpleCursorAdapter(this, R.layout.item, cursor, new String[]{"name", "phone"}, new int[]{R.id.name, R.id.phone}); listView.setAdapter(simplecursoradapter); } /*方法一：通过适配器SimpleAdapter来显示ListView的数据*/ private void show() { List
            
              persons = new ArrayList
             
              (); PersonService service = new PersonService(MyActivity.this); persons = service.getScrollData(0, 20); List
              
               
                > datalist = new ArrayList
                
                 
                  >(); for (Person person : persons) { HashMap
                  
                    item = new HashMap
                   
                    (); item.put("name", person.getName()); item.put("phone", person.getPhone()); datalist.add(item); } /* //这里new String[]{"name", "phone"}中的name 以及phone 要和 item.put("name", person.getName()); item.put("phone", person.getPhone());中的对应起来*/ SimpleAdapter simpleAdapter = new SimpleAdapter(this, datalist, R.layout.item, new String[]{"name", "phone"}, new int[]{R.id.name, R.id.phone}); listView.setAdapter(simpleAdapter); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.my, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); }}

1 对应的这三种方式的总结：

调用SimpleCursorAdapter方式的时候，使用getItemAtPosition(position)函数返回List的数据集合中的元素是Cursor类型

//parent就是我们单击的Listview

ListView listView1 = (ListView)parent;

Cursor cursor = (Cursor)listView1.getItemAtPosition(position);

String name = cursor.getString(cursor.getColumnIndex("name"));

String phone =cursor.getString(cursor.getColumnIndex("phone"));

Toast.makeText(MyActivity.this,name+","+phone,Toast.LENGTH_LONG).show();

2、调用自定义适配器的时候，getItemAtPosition(position)函数返回的是Person类型，

ListView listView1 = (ListView)parent;

Person person= (Person)listView1.getItemAtPosition(position);

Toast.makeText(MyActivity.this,person.getName()+","+person.getPhone(),Toast.LENGTH_SHORT).show();

3、调用SimpleAdapter来显示ListView的数据，getItemAtPosition(position)返回的是HashMap的数据

ListView listView1 = (ListView)parent;

HashMap<String,String> map= (HashMap<String,String>)listView1.getItemAtPosition(position);
String name =map.get("name");
String phone = map.get("phone");
Toast.makeText(MyActivity.this,name+","+phone,Toast.LENGTH_LONG).show();

我们来看看界面的布局文件：