从数据库里查询数据展示到listview上的案例

编写一个从数据库里查询数据展示到listview上的案例

运行结果：点击find按钮，会将数据库中添加的数据显示在List View上

结果如下：

创建如图所示：

代码如下：

PersonAdapter

package cn.edu.bzu.datashow.adapter;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.TextView;import java.util.List;import cn.edu.bzu.datashow.R;import cn.edu.bzu.datashow.entity.Person;public class PersonAdapter extends ArrayAdapter<Person> {   private int resourceId;   public PersonAdapter(Context context, int textViewResourceId,                   List<Person> objects) {      super(context, textViewResourceId, objects);      resourceId = textViewResourceId;   }   @Override   public View getView(int position, View convertView, ViewGroup parent) {      Person person= getItem(position);      View view;      ViewHolder viewHolder;      if (convertView == null) {         //任务 补充完整         view = LayoutInflater.from(getContext()).inflate(resourceId, null);         viewHolder = new ViewHolder();         viewHolder.tvName = (TextView) view.findViewById(R.id.tvName);         viewHolder.tvPhone = (TextView) view.findViewById(R.id.tvPhone);         view.setTag(viewHolder);      } else {         view = convertView;         viewHolder = (ViewHolder) view.getTag();      }      viewHolder.tvName.setText(person.getName());      viewHolder.tvPhone.setText(person.getPhone());      return view;   }      class ViewHolder {      TextView tvName;      TextView tvPhone;   }}

PersonDao:

package cn.edu.bzu.datashow.dao;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 cn.edu.bzu.datashow.db.PersonDBHelper;import cn.edu.bzu.datashow.entity.Person;/** * Created by fengj on 2017/5/10. */public class PersonDao {    private PersonDBHelper personDBHelper;    public PersonDao(Context context){        personDBHelper=new PersonDBHelper(context);    }    public void add(Person person){        SQLiteDatabase sqLiteDatabase=personDBHelper.getWritableDatabase();        ContentValues contentValues=new ContentValues();        contentValues.put("name",person.getName());        contentValues.put("phone",person.getPhone());        sqLiteDatabase.insert("info",null,contentValues);    }    public List<Person> getPersons(){        //任务 完成查询所有数据的方法        List<Person> persons=new ArrayList<Person>();        SQLiteDatabase sqLiteDatabase=personDBHelper.getWritableDatabase();        Cursor cursor=sqLiteDatabase.query("info",null,null,null,null,null,null);        while(cursor.moveToNext()){           int id= cursor.getInt(cursor.getColumnIndex("_id"));            String name=cursor.getString(cursor.getColumnIndex("name"));            String phone=cursor.getString(cursor.getColumnIndex("phone"));            Person person=new Person(name,phone);            person.setId(id);            persons.add(person);        }        return persons;    }} 

PersonDBHelper:

package cn.edu.bzu.datashow.db;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;/** * Created by fengj on 2017/5/10. *///任务：修正问题public class PersonDBHelper extends SQLiteOpenHelper {    //数据库的名称为person.db ,数据库的版本为1    public PersonDBHelper(Context context) {        super(context,"person.db", null, 1);    }    @Override    public void onCreate(SQLiteDatabase db) {        db.execSQL("create table info(_id integer primary key,name varchar(20),phone varchar(20))");    }    @Override    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {    }} 

MainActivity:

package cn.edu.bzu.datashow;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.widget.ListView;import java.util.List;import cn.edu.bzu.datashow.adapter.PersonAdapter;import cn.edu.bzu.datashow.dao.PersonDao;import cn.edu.bzu.datashow.entity.Person;public class MainActivity extends AppCompatActivity {    private PersonDao personDao;    private ListView lvPersons;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        lvPersons= (ListView) findViewById(R.id.lvPersons);        personDao=new PersonDao(this);        personDao.add(new Person("张三","13476089006"));        personDao.add(new Person("李四","13476089008"));    }    public void find(View view){        //任务 查询数据库中的所有person，显示在列表中        List<Person> persons=personDao.getPersons();        PersonAdapter personAdapter=new PersonAdapter(this,R.layout.item,persons);        lvPersons.setAdapter(personAdapter);    }}

Activity-main.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_main"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:orientation="vertical"    tools:context="cn.edu.bzu.datashow.MainActivity">    <ListView        android:id="@+id/lvPersons"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:divider="@color/colorPrimary"        android:layout_weight="1"       />    <Button        android:text="Find"        android:layout_gravity="center_horizontal"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:layout_below="@id/lvPersons"        android:onClick="find"        android:id="@+id/btnFind" /></LinearLayout> 

item.xml:

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/activity_shop"    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    android:orientation="vertical"    >    <TextView        android:text="名字"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/tvName"        android:textSize="24sp"        />    <TextView        android:text="电话"        android:layout_marginTop="10dp"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:textSize="18sp"        android:id="@+id/tvPhone"       /></LinearLayout>

运行出来就好啦！