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SQLite
主界面
<?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:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="cn.edu.niit.sqlite.MainActivity"> <EditText android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/et"/> <LinearLayout android:orientation="horizontal" android:layout_width="match_parent" android:layout_height="wrap_content"> <Button android:layout_weight="1" android:layout_width="0dp" android:layout_height="wrap_content" android:id="@+id/add" android:text="增加新纪录"/> <Button android:layout_weight="1" android:layout_width="0dp" android:layout_height="wrap_content" android:id="@+id/del" android:text="删除一条记录"/> </LinearLayout> <ListView android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/lv"></ListView> </LinearLayout>
新建一个item
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:id="@+id/name" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text=""/> </LinearLayout>
封装相关信息
package cn.edu.niit.sqlite; import java.io.Serializable; /** * Created by 10403 on 2017/5/16. */ public class Person implements Serializable { private int _id; private String name; public Person() { } public Person(String name){ this.name=name; } public int get_id() { return _id; } public void set_id(int _id) { this._id = _id; } public String getName() { return name; } public void setName(String name) { this.name = name; } }
创建数据库
package cn.edu.niit.sqlite; import android.content.Context; import android.database.sqlite.SQLiteDatabase; import android.database.sqlite.SQLiteOpenHelper; /** * Created by 10403 on 2017/5/16. */ public class MyDBHelper extends SQLiteOpenHelper { //person表的创建语句,字段包括:自增关键字id、姓名name private String sql = "create table person(_id integer primary key autoincrement, " + "name text not null)"; public MyDBHelper(Context context) { super(context, "personInfo", null, 1); } @Override public void onCreate(SQLiteDatabase db) { db.execSQL(sql); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("drop table if exists person"); onCreate(db); } }
加载listview
package cn.edu.niit.sqlite; import android.content.Context; import android.database.Cursor; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.CursorAdapter; import android.widget.TextView; /** * Created by 10403 on 2017/5/16. */ public class MyCursorAdapter extends CursorAdapter { public MyCursorAdapter(Context context, Cursor cursor) { super(context, cursor, 0); } // 加载listView的item的布局 @Override public View newView(Context context, Cursor cursor, ViewGroup viewGroup) { return LayoutInflater.from(context).inflate(R.layout.item,viewGroup,false); } //给item的每个主键赋值 @Override public void bindView(View view, Context context, Cursor cursor) { TextView name=(TextView)view.findViewById(R.id.name); name.setText(cursor.getString(cursor.getColumnIndex("name"))); } }
插入数据
package cn.edu.niit.sqlite; import android.content.Context; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; /** * Created by 10403 on 2017/5/16. */ public class PersonDAO { private Context context;//Activity上下文 private MyDBHelper helper;//创建、升级、打开数据库 private SQLiteDatabase db;//对表进行CRUD public PersonDAO(Context context) { helper = new MyDBHelper(context); } public void insert(Person person){ //1. 打开数据库 db = helper.getWritableDatabase(); // 2. 生成数据集合 String sql = "insert into person(name) values(?)"; db.execSQL(sql,new Object[]{person.getName()}); } public Cursor selectAll() { db = helper.getReadableDatabase(); Cursor cursor = db.query("person",null,null,null,null,null,null); return cursor; } public void delete(int id){ db = helper.getWritableDatabase(); db.delete("person", "_id=?", new String[] {String.valueOf(id)}); String sql = "delete from person where _id=?"; db.execSQL(sql, new Object[]{id}); } }
MainActivity
package cn.edu.niit.sqlite; import android.content.Intent; import android.database.Cursor; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.text.TextUtils; import android.view.View; import android.widget.AdapterView; import android.widget.Button; import android.widget.EditText; import android.widget.ListView; import android.widget.Toast; public class MainActivity extends AppCompatActivity implements View.OnClickListener{ private EditText writer; private ListView personList; private Button btnadd; private Button btndel; private PersonDAO personDAO; private MyCursorAdapter adapter; private Person person; private Cursor cursor; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); personList=(ListView)findViewById(R.id.lv); btnadd=(Button)findViewById(R.id.add); btnadd.setOnClickListener(this); btndel=(Button)findViewById(R.id.del); btndel.setOnClickListener(this); writer=(EditText)findViewById(R.id.et) ; //创建adapter personDAO=new PersonDAO(this); Cursor cursor=personDAO.selectAll(); if (cursor!=null){ adapter=new MyCursorAdapter(this,cursor); personList.setAdapter(adapter); } //ListView的item点击事件 personList.setOnItemClickListener(new AdapterView.OnItemClickListener(){ @Override public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) { Cursor cursor = (Cursor) adapterView.getItemAtPosition(i); if(cursor != null) { cursor.moveToPosition(i); person=new Person(); person.set_id(cursor.getInt(cursor.getColumnIndex("_id"))); person.setName(cursor.getString(cursor.getColumnIndex("name"))); } } }); } @Override public void onClick(View view) { switch (view.getId()) { case R.id.add: String name = writer.getText().toString(); if (TextUtils.isEmpty(name)) { Toast.makeText(this, "姓名不能为空", Toast.LENGTH_LONG).show(); return; }else { personDAO = new PersonDAO(this); person = new Person(name); personDAO.insert(person); cursor=personDAO.selectAll(); adapter.changeCursor(cursor); personList.setAdapter(adapter); Toast.makeText(this, "添加成功", Toast.LENGTH_SHORT).show(); } break; case R.id.del: if(person != null){ personDAO.delete(person.get_id()); personDAO=new PersonDAO(this); cursor = personDAO.selectAll(); adapter = new MyCursorAdapter(this, cursor); adapter.changeCursor(cursor); personList.setAdapter(adapter); Toast.makeText(this,"删除成功",Toast.LENGTH_LONG).show(); } } }
SQLite
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