安卓sqlite数据库的使用

创建数据库逻辑代码：

<span style="font-size:18px;">package com.example.day14_work;import android.annotation.SuppressLint;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.database.sqlite.SQLiteOpenHelper;import android.util.Log;import android.widget.Toast;public class MySqlite extends SQLiteOpenHelper{static String NAME="work.db";static int VERSION=1;//上下文对象，数据库名称，游标工厂，数据库的版本public MySqlite(Context context, String name, CursorFactory factory,int version) {super(context, name, factory, version);// TODO Auto-generated constructor stub}public MySqlite(Context context){super(context,NAME,null,VERSION);}//数据库第一次创建时调用@Overridepublic void onCreate(SQLiteDatabase db) { String sql="create table myInformation(color varchar(10),contents varchar(100))"; db.execSQL(sql);}//数据库版本发生改变时调用，即数据库版本升级@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stub}//数据库版本发生改变时调用，即数据库版本降级，只有发生重大错误时才会调用@SuppressLint("NewApi") @Overridepublic void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {// TODO Auto-generated method stubsuper.onDowngrade(db, oldVersion, newVersion);}//每次打开数据库时调用，用于验证数据库打没打开@Overridepublic void onOpen(SQLiteDatabase db) {// TODO Auto-generated method stubsuper.onOpen(db);Log.i("===onOpen===", "数据库打开");}}</span>

第一个Activity的逻辑代码文件：

<span style="font-size:18px;">package com.example.day14_work;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import com.example.day14_work.adapter.MyAdapter;import android.app.Activity;import android.content.Intent;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.ArrayAdapter;import android.widget.BaseAdapter;import android.widget.GridView;import android.widget.SimpleAdapter;import android.widget.TextView;import android.widget.Toast;public class MainActivity extends Activity {GridView gv;List<Map<String,Object>> list;MySqlite helper;MyAdapter adapter;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        gv=(GridView) findViewById(R.id.gv);helper=new MySqlite(getApplicationContext());        getData();        adapter=new MyAdapter(list,MainActivity.this);        //SimpleAdapter adapter=new SimpleAdapter(getApplicationContext(), list, R.layout.style, new String[]{"content"},new int[]{R.id.tv});        gv.setAdapter(adapter);    }    @Override    protected void onRestart() {    super.onRestart();        getData();        gv.setAdapter(new MyAdapter(list,MainActivity.this));    }    public void click(View v)    {    Intent intent=new Intent(MainActivity.this,Second.class);    startActivity(intent);    }    public void getData()    {    list=new ArrayList<Map<String,Object>>();    SQLiteDatabase db=helper.getReadableDatabase();String sql="select * from myInformation";Cursor cursor = db.rawQuery(sql, null);while(cursor.moveToNext()){Map<String,Object> map=new HashMap<String, Object>();String color=cursor.getString(cursor.getColumnIndex("color"));String content=cursor.getString(cursor.getColumnIndex("contents"));map.put("color", color);map.put("content", content);list.add(map);//Toast.makeText(getApplicationContext(),color+"\n"+content, 0).show();}db.close();    }    }</span>

自定义适配器类逻辑代码：

<span style="font-size:18px;">package com.example.day14_work.adapter;import java.util.List;import java.util.Map;import android.content.Context;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.TextView;import com.example.day14_work.R;public class MyAdapter extends BaseAdapter{List<Map<String,Object>> list;Context context;public MyAdapter(List<Map<String, Object>> list, Context context) {super();this.list = list;this.context = context;}@Overridepublic int getCount() {return list.size();}@Overridepublic Object getItem(int position) {return list.get(position);}@Overridepublic long getItemId(int position) {return position;}@Overridepublic View getView(int position, View view, ViewGroup parent) {ViewHolder holder = null;if(view==null){holder=new ViewHolder();view=LayoutInflater.from(context).inflate(R.layout.style, null);holder.tv=(TextView) view.findViewById(R.id.tv);view.setTag(holder);}else{holder=(ViewHolder) view.getTag();}String data = list.get(position).get("content").toString();String mycolor = list.get(position).get("color").toString();holder.tv.setText(data);if("红色".equals(mycolor)){holder.tv.setTextColor(android.graphics.Color.RED);}else if("蓝色".equals(mycolor)){holder.tv.setTextColor(android.graphics.Color.BLUE);}return view;}class ViewHolder{TextView tv;}}</span>

第二个Activity的逻辑代码文件：

<span style="font-size:18px;">package com.example.day14_work;import android.app.Activity;import android.content.Intent;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.view.View;import android.widget.EditText;import android.widget.RadioButton;import android.widget.RadioGroup;import android.widget.RadioGroup.OnCheckedChangeListener;import android.widget.Toast;public class Second extends Activity{RadioGroup rg;EditText et;String content,selected;MySqlite helper;@Overrideprotected void onCreate(Bundle savedInstanceState) {// TODO Auto-generated method stubsuper.onCreate(savedInstanceState);setContentView(R.layout.second);rg=(RadioGroup) findViewById(R.id.rg);et=(EditText) findViewById(R.id.et);rg.setOnCheckedChangeListener(new OnCheckedChangeListener() {@Overridepublic void onCheckedChanged(RadioGroup group, int checkedId) {RadioButton rb=(RadioButton) findViewById(checkedId);selected=rb.getText().toString();if("红色".equals(selected)){et.setTextColor(android.graphics.Color.RED);}else if("蓝色".equals(selected)){et.setTextColor(android.graphics.Color.BLUE);}//Toast.makeText(getApplicationContext(), selected, 0).show();}});helper=new MySqlite(getApplicationContext());}public void click(View v){content=et.getText().toString();SQLiteDatabase db=helper.getReadableDatabase();String sql="insert into myInformation values('"+selected+"','"+content+"')";db.execSQL(sql);Intent intent=new Intent();finish();}}</span>

第一个Activity布局文件：

<span style="font-size:18px;"><RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" ><LinearLayout         android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal"        android:id="@+id/ll"        android:gravity="center">        <TextView         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="主页"        android:textSize="26sp"/>    <Button         android:id="@+id/add"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="添加"        android:onClick="click"        android:textSize="24sp"        android:layout_marginLeft="30dp"/>    </LinearLayout>    <GridView        android:id="@+id/gv"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:numColumns="3"        android:layout_below="@+id/ll"        android:layout_marginTop="20dp"/>    </RelativeLayout></span>

第二个Activity布局文件

<span style="font-size:18px;"><?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="vertical" >    <LinearLayout         android:layout_width="match_parent"    android:layout_height="wrap_content"   android:orientation="horizontal"   android:gravity="center_horizontal" >    <TextView         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="添加数据"        android:textSize="26sp"/>    <Button         android:id="@+id/finish"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="完成"        android:onClick="click"        android:textSize="24sp"        android:layout_marginLeft="20dp"/>    </LinearLayout>        <RadioGroup         android:id="@+id/rg"        android:layout_width="match_parent"        android:layout_height="wrap_content"        android:orientation="horizontal"        android:gravity="center"        android:layout_marginTop="20dp">        <RadioButton         android:id="@+id/red"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="红色"        android:textSize="24sp"/>        <RadioButton         android:id="@+id/blue"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="蓝色"        android:textSize="24sp"/>    </RadioGroup>    <EditText         android:id="@+id/et"        android:layout_width="match_parent"        android:layout_height="match_parent"        android:background="#00ff00"        android:hint="请输入内容"        android:gravity="center"/></LinearLayout></span>

自定义适配器用的样式布局文件：

<span style="font-size:18px;"><?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="vertical" >    <TextView         android:id="@+id/tv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"/></LinearLayout></span>