Fragment复习和Sqlite练习

最新推荐文章于 2023-11-28 20:56:08 发布

原创最新推荐文章于 2023-11-28 20:56:08 发布 · 277 阅读

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本文回顾了Android中的Fragment使用，强调了布局设计和主要代码实现。同时，进行了Sqlite数据库的操作练习，包括布局设计、SQLiteOpenHelper的继承以及增删改查的完整代码示例。

Day10.14作业

Fragment复习

重点布局

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <android.support.v4.view.ViewPager
        android:id="@+id/vp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

    </android.support.v4.view.ViewPager>

    <TextView
        android:id="@+id/daojishi"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="倒计时"
        android:textColor="#000"
        android:layout_alignParentRight="true"
        android:layout_marginTop="10dp"
        android:layout_marginRight="10dp"
        android:textSize="20sp"
        android:visibility="gone"/>

    <Button
        android:id="@+id/jump"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="点击跳转"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="400dp"
        android:visibility="gone"/>
</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Main2Activity">
                <android.support.design.widget.TabLayout
                    android:id="@+id/tl"
                    android:layout_width="match_parent"
                    android:layout_height="50dp">
                </android.support.design.widget.TabLayout>
                <android.support.v4.view.ViewPager
                    android:orientation="vertical"
                    android:id="@+id/vp"
                    android:layout_below="@+id/tl"
                    android:layout_width="match_parent"
                    android:layout_height="match_parent">
                </android.support.v4.view.ViewPager>
</RelativeLayout>

主要代码（Fragment代码省略）

package com.example.day1014homework;

import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

import com.example.day1014homework.MainFragment.OneFragment;
import com.example.day1014homework.MainFragment.ThreeFragment;
import com.example.day1014homework.MainFragment.TwoFragment;

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {

    private ViewPager vp;
    private TextView daojishi;
    private Button jump;




    private List<Fragment> fragmentList;
    private Timer timer1 = new Timer();//页面跳转用
    private Timer timer2 = new Timer();//倒计时用
    private int index = 0;
    private int time = 6;
    Handler handler = new Handler(){
        @Override
        public void handleMessage(Message msg) {
                if (msg.what == 100){
                    vp.setCurrentItem(index);
                    index++;
                    if (index == fragmentList.size()){
                        daojishi.setVisibility(View.VISIBLE);
                        jump.setVisibility(View.VISIBLE);
                        timer1.cancel();
                        timer2.schedule(new TimerTask() {
                            @Override
                            public void run() {
                                    handler.sendEmptyMessage(101);
                            }
                        },0,1000);
                    }
                }
                if (msg.what == 101){
                        daojishi.setText("倒计时"+(--time)+"秒");
                        if (time == 0){
                            timer2.cancel();
                            Intent intent = new Intent(MainActivity.this, Main2Activity.class);
                            startActivity(intent);
                            finish();
                        }
                }
        }
    };

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

        //初始化
        vp = (ViewPager) findViewById(R.id.vp);
        daojishi = (TextView) findViewById(R.id.daojishi);
        jump = (Button) findViewById(R.id.jump);

        fragmentList = new ArrayList<>();

        //三个Fragment
        OneFragment oneFragment = new OneFragment();
        TwoFragment twoFragment = new TwoFragment();
        ThreeFragment threeFragment = new ThreeFragment();

        fragmentList.add(oneFragment);
        fragmentList.add(twoFragment);
        fragmentList.add(threeFragment);

        //加载fragment
        vp.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int i) {
                return fragmentList.get(i);
            }

            @Override
            public int getCount() {
                return fragmentList.size();
            }
        });
        //页面跳转
        timer1.schedule(new TimerTask() {
            @Override
            public void run() {
                    handler.sendEmptyMessage(100);
            }
        },0,1000);

        jump.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                timer2.cancel();
                Intent intent = new Intent(MainActivity.this, Main2Activity.class);
                startActivity(intent);
                finish();
            }
        });

    }
}

package com.example.day1014homework;

import android.support.annotation.Nullable;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.LinearLayout;

import com.example.day1014homework.Main2Fragment.Blank1Fragment;
import com.example.day1014homework.Main2Fragment.Blank2Fragment;
import com.example.day1014homework.Main2Fragment.Blank3Fragment;

import java.util.ArrayList;
import java.util.List;

public class Main2Activity extends AppCompatActivity {
    private TabLayout tl;
    private ViewPager vp;
    private List<Fragment> fragmentList = new ArrayList<>();
    private List<String> page = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        tl = (TabLayout) findViewById(R.id.tl);
        vp = (ViewPager) findViewById(R.id.vp);

        Blank1Fragment blank1Fragment = new Blank1Fragment();
        Blank2Fragment blank2Fragment = new Blank2Fragment();
        Blank3Fragment blank3Fragment = new Blank3Fragment();

        fragmentList.add(blank1Fragment);
        fragmentList.add(blank2Fragment);
        fragmentList.add(blank3Fragment);
        for (int i = 0; i < 3; i++) {
            page.add("第"+(i+1)+"页");
        }

        vp.setAdapter(new FragmentPagerAdapter(getSupportFragmentManager()) {
            @Override
            public Fragment getItem(int i) {
                return fragmentList.get(i);
            }

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

            @Nullable
            @Override
            public CharSequence getPageTitle(int position) {
                return page.get(position);
            }
        });

        tl.setupWithViewPager(vp);


    }



}

Sqlite练习

布局

<?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:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:orientation="vertical">

   <Button
       android:id="@+id/zeng"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="增加"
       android:onClick="click"/>
    <Button
        android:id="@+id/shan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="删除"
        android:onClick="click"/>
    <Button
        android:id="@+id/gai"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="修改"
        android:onClick="click"/>
    <Button
        android:id="@+id/cha"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="查询"
        android:onClick="click"/>

</LinearLayout>

创建一个类继承 SQLiteOpenHelper

package com.example.app2.sql;

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

public class MySqlHelp  extends SQLiteOpenHelper {
    /**
     *
     * @param context  上下文对象
     * @param name      数据库的名字
     * @param factory   工厂
     * @param version   数据库版本
     */
    public MySqlHelp(Context context,  String name,  SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    //用户数据库的创建  有数据库的时候  不会再执行
    @Override
    public void onCreate(SQLiteDatabase db) {
        //db用于对数据库的增、删、改、查
        db.execSQL("create table student (id integer primary key autoincrement,name varchar(20),address varchar(20))");
        db.beginTransaction();
        for (int i = 0; i < 10; i++) {
            db.execSQL("insert into student values(null,'过江龙遇下山虎','小伙不由你做主')");
        }
        //成功
        db.setTransactionSuccessful();
        //结束
        db.endTransaction();
    }

    //更新数据库用的
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

增删改查的代码（两种方法）

package com.example.app2;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

import com.example.app2.sql.MySqlHelp;

public class MainActivity extends AppCompatActivity {

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

        MySqlHelp mySqlHelp = new MySqlHelp(this, "person.db", null, 1);

        //可读可写，当磁盘满了，会重新尝试打开
        db= mySqlHelp.getReadableDatabase();

    }

    public void click(View view) {
        switch (view.getId()){
            case R.id.zeng:
                    //方法
//                ContentValues contentValues = new ContentValues();
//                contentValues.put("name","卤蛋");
//                contentValues.put("address","烟台");
//                db.insert("student",null,contentValues);
                    //原生
                String sql = "insert into student(name,address) values (?,?)";
                db.execSQL(sql,new Object[]{"大金牙","上海滩"});
                break;
            case R.id.shan:
                    String sql2 ="delete from student where id = ?";
                    db.execSQL(sql2,new Object[]{2});
                break;

            case R.id.gai:
                //原生
//                String sql3 = "update student set name = ? where id = ?";
//                db.execSQL(sql3,new Object[]{"精神小伙",3});

                //方法
                ContentValues contentValues = new ContentValues();
                contentValues.put("address","不知道");
                db.update("student",contentValues,"id=?",new String[]{"1"});
                break;

            case R.id.cha:
                    //原生
//                String sql = "select * from student where id =?";
//                Cursor cursor = db.rawQuery(sql, new String[]{"2"});
//                if (cursor !=null){
//                    while (cursor.moveToNext()){
//                        String id = cursor.getString(cursor.getColumnIndex("id"));
//                        String name = cursor.getString(cursor.getColumnIndex("name"));
//                        String address = cursor.getString(cursor.getColumnIndex("address"));
//                        Toast.makeText(this, id+"--"+name+"--"+address, Toast.LENGTH_SHORT).show();
//                    }
//
//                }
//                cursor.close();
                //方法
                Cursor cursor = db.query("student", null, null, null, null, null, null);
                if (cursor != null){
                    while (cursor.moveToNext()){
                        String id = cursor.getString(cursor.getColumnIndex("id"));
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String address = cursor.getString(cursor.getColumnIndex("address"));
                        Toast.makeText(this, id+"--"+name+"--"+address, Toast.LENGTH_SHORT).show();
                    }
                }
                cursor.close();
                break;
        }
    }
}