android中增删改查数据库数据并加载到ListView

public class MainActivity extends Activity {

private MyOpenHelper myOpenHelper;
private List<Person> lists;
private ListView lv;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

//[0]找到lv

lv = (ListView) findViewById(R.id.lv);

myOpenHelper = new MyOpenHelper(getApplicationContext());

//[1]定义一个集合用来存listview 要展示的数据
lists = new ArrayList<Person>();

//打开或者创建数据库  如果是第一次就是创建
//      SQLiteDatabase sqLiteDatabase = myOpenHelper.getWritableDatabase();
//打开或者创建数据库  如果是第一次就是创建     如果磁盘满了 返回只读的
//      SQLiteDatabase readableDatabase = myOpenHelper.getReadableDatabase();

}

//点击按钮增加一条记录
public void click1(View v){
//[1]获取数据库对象
SQLiteDatabase db = myOpenHelper.getWritableDatabase();
//[2]执行增加一条的sql语句
//      db.execSQL("insert into info(name,phone) values(?,?)", new Object[]{"张三","1388888"});
/**
* table 表名
* ContentValues 内部封装了一个map   key:  对应列的名字  value对应的值
*/
ContentValues values = new ContentValues();
values.put("name", "王五");
values.put("phone", "110");
//返回值代表插入新行的id
long insert = db.insert("info", null, values); //底层就在组拼sql语句
//[3]数据库用完需要关闭
db.close();

if (insert>0) {
Toast.makeText(getApplicationContext(), "添加成功", 1).show();
}else {
Toast.makeText(getApplicationContext(), "添加fail", 1).show();
}

}

//删除
public void click2(View v){
SQLiteDatabase db = myOpenHelper.getWritableDatabase();
//      db.execSQL("delete from info where name=?", new Object[]{"张三"});

//返回值代表影响的行数
int delete = db.delete("info", "name=?", new String[]{"王五"});
db.close();

Toast.makeText(getApplicationContext(), "删除了"+delete+"行", 0).show();

}

//更新
public void click3(View v){
SQLiteDatabase db = myOpenHelper.getWritableDatabase();

//      db.execSQL("update info set phone=? where name=? ", new Object[]{"138888888","张三"});

ContentValues values = new ContentValues();
values.put("phone", "114");
//代表更新了多少行
int update = db.update("info", values, "name=?", new String[]{"王五"});
db.close();

Toast.makeText(getApplicationContext(), "更新了"+update+"行", 0).show();
}

//查找
public void click4(View v){

SQLiteDatabase db = myOpenHelper.getReadableDatabase();

//columns 代表你要查询的列
//selection 根据什么查询phone
//      Cursor cursor = db.query("info", new String[]{"name","phone"}, "name=?", new String[]{"王五"}, null, null, null);
Cursor cursor = db.query("info", null,null, null, null, null, null);

//      Cursor cursor = db.rawQuery("select * from info", null);
if (cursor!= null&&cursor.getCount()>0) {
while(cursor.moveToNext()){
//columnIndex代表列的索引
String name = cursor.getString(1);
String phone = cursor.getString(2);

//把数据封装到javabean
Person person = new Person();
person.setName(name);
person.setPhone(phone);

//把javabena对象加入到集合
lists.add(person);

}

//设置数据适配器
lv.setAdapter(new MyAdapter());

}

}

//定义listview 的数据适配器
private class MyAdapter extends BaseAdapter{

@Override
public int getCount() {
return lists.size();
}

@Override
public Object getItem(int position) {
return null;
}

@Override
public long getItemId(int position) {
return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view;
if (convertView == null) {
//创建新的view 对象
view = View.inflate(getApplicationContext(), R.layout.item, null);

}else{
view = convertView;

}
//[找到控件用来显示数据]
TextView tv_name = (TextView) view.findViewById(R.id.tv_name);
TextView tv_phone = (TextView) view.findViewById(R.id.tv_phone);

//如何显示数据
Person person = lists.get(position);
tv_name.setText(person.getName());
tv_phone.setText(person.getPhone());

return view;
}

}

}

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class MyOpenHelper extends SQLiteOpenHelper {

/**
*
* @param context  上下文
* name:数据库的名字
* factory 目的创建cursor对象
*
* version 数据库的版本   从1开始
*/
public MyOpenHelper(Context context) {
super(context, "itheima.db", null,4);

}

/**
* Called when the database is created for the first time.
* 当数据库第一次创建的时候调用
* 那么这个方法特别适合做表结构的初始化  创建表就是写sql语句
*/
@Override
public void onCreate(SQLiteDatabase db) {

//id 一般以_id

db.execSQL("create table info(_id integer primary key autoincrement,name varchar(20),phone varchar(20))");

}
/**
* Called when the database needs to be upgraded
* 当数据库版本升级的时候调用
*
* 这个方法适合做   表结构的更新
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

db.execSQL("alter table info add phone varchar(20)");

}

}

public class Person {

private String name;
private String 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;
}

}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".MainActivity" >

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="click1"
android:text="add" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="click2"
android:text="delete" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="click3"
android:text="update" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:onClick="click4"
android:text="find" />

<ListView
android:id="@+id/lv"
android:layout_width="match_parent"
android:layout_height="match_parent"
></ListView>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TextView
android:id="@+id/tv_name"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="agagag"
android:textSize="20sp"
android:layout_weight="1" />

<TextView
android:id="@+id/tv_phone"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="agagag"
android:textSize="20sp"
android:textColor="#ff0000"
android:layout_weight="1" />

</LinearLayout>