Android Studio实例:绿豆通讯录

步骤一：

了解项目结构

步骤二：

首先是继承SQLiteOpenHelper的数据库自定义类

创建Java文件MyHelper.java

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

public class MyHelper extends SQLiteOpenHelper {
    public MyHelper(Context context) {
//上下文、数据库名、工厂、版本
        super(context, "itcast.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
//创建数据表 db.execSQL执行建表语句
        db.execSQL("CREATE TABLE information(_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR(20), phone VARCHAR(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    }
}

步骤三：主界面的界面代码的创建

1.主界面：

效果

代码：activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<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:background="@drawable/bg"
    android:paddingLeft="16dp"
    android:paddingTop="16dp"
    android:paddingRight="16dp"
    android:paddingBottom="16dp"
    tools:context=".MainActivity">

    <LinearLayout
        android:id="@+id/ll_name"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/ll_phone"
        android:layout_alignStart="@+id/ll_btn"
        android:layout_alignLeft="@+id/ll_btn">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="姓  名 ："
            android:textSize="18sp" />

        <EditText
            android:id="@+id/et_name"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入姓名"
            android:textSize="16sp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/ll_phone"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/ll_btn"
        android:layout_alignStart="@+id/ll_name"
        android:layout_alignLeft="@+id/ll_name"
        android:layout_marginBottom="10dp">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="电  话 ："
            android:textSize="18sp" />

        <EditText
            android:id="@+id/et_phone"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="请输入手机号码"
            android:textSize="16sp" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/ll_btn"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true">

        <Button
            android:id="@+id/btn_add"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginRight="2dp"
            android:layout_weight="1"
            android:background="#B9B9FF"
            android:text="添加"
            android:textSize="18sp" />

        <Button
            android:id="@+id/btn_query"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginRight="2dp"
            android:layout_weight="1"
            android:background="#DCB5FF"
            android:text="查询"
            android:textSize="18sp" />

        <Button
            android:id="@+id/btn_update"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginRight="2dp"
            android:layout_weight="1"
            android:background="#E6CAFF"
            android:text="修改"
            android:textSize="18sp" />

        <Button
            android:id="@+id/btn_delete"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:background="#ACD6FF"
            android:text="删除"
            android:textSize="18sp" />
    </LinearLayout>
    <ListView
        android:id="@+id/lv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@+id/ll_btn"
        android:layout_margin="5dp"
        android:divider="#d9d9d9"
        android:dividerHeight="2dp">
    </ListView>

</RelativeLayout>

2.列表功能页:

代码：

<?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="wrap_content">
    <ImageView
        android:id="@+id/item_image"
        android:layout_width="100px"
        android:layout_height="100px"
        android:layout_margin="8dp"
        android:background="@drawable/tx" />
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical">

        <TextView
            android:id="@+id/item_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginTop="3sp"
            android:text="姓名"
            android:textColor="#00FFFF"
            android:textSize="17sp" />

        <TextView
            android:id="@+id/item_phone"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="电话"
            android:textColor="#7FFFAA"
            android:textSize="16sp" />
    </LinearLayout>
</LinearLayout>

步骤四： 逻辑代码MainActivity

import androidx.appcompat.app.AppCompatActivity;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.provider.ContactsContract;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    MyHelper myHelper;
    private EditText mEtName;
    private EditText mEtPhone;
    private Button mBtnAdd;
    private Button mBtnQuery;
    private Button mBtnUpdate;
    private Button mBtnDelete;

    private ListView mList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //new创建对象  传递上下文this
        myHelper = new MyHelper(this);
        init();//初始化控件 绑定控件
    }

    private void init() {
        mEtName = (EditText) findViewById(R.id.et_name);
        mEtPhone = (EditText) findViewById(R.id.et_phone);
        mBtnAdd = (Button) findViewById(R.id.btn_add);
        mBtnQuery = (Button) findViewById(R.id.btn_query);
        mBtnUpdate = (Button) findViewById(R.id.btn_update);
        mBtnDelete = (Button) findViewById(R.id.btn_delete);
        mBtnAdd.setOnClickListener(this);
        mBtnQuery.setOnClickListener(this);
        mBtnUpdate.setOnClickListener(this);
        mBtnDelete.setOnClickListener(this);
        mList = (ListView) findViewById(R.id.lv);
    }

    @Override
    public void onClick(View v) {
        String name;
        String phone;
        SQLiteDatabase db;
        ContentValues values;
        int id = v.getId();
        if (id == R.id.btn_add) { //添加数据
            name = mEtName.getText().toString();
            phone = mEtPhone.getText().toString();
            db = myHelper.getWritableDatabase();//获取可读写SQLiteDatabse对象
            values = new ContentValues();       // 创建ContentValues对象
            values.put("name", name);           // 将数据添加到ContentValues对象
            values.put("phone", phone);         // 将数据添加到ContentValues对象
            db.insert("information", null, values);//执行方法insert向数据表添加数据
            Toast.makeText(this, "信息已添加", Toast.LENGTH_SHORT).show();//提示框
            db.close();//关闭db
        } else if (id == R.id.btn_query) { //查询数据
            Toast.makeText(this, "query", Toast.LENGTH_SHORT).show();
            db = myHelper.getReadableDatabase();
            if (mEtName.getText().toString().isEmpty()) {
                Cursor cursor = db.query("information", null, null, null, null, null, null);//Cursor作为一种游标的存储类型，来存储获取到的数据
                SimpleCursorAdapter spcAdapter = new SimpleCursorAdapter(this, R.layout.list_item, cursor,
                        new String[]{"name", "phone"}, new int[]{R.id.item_name, R.id.item_phone});
                mList.setAdapter(spcAdapter);
            } else {
                Cursor cursor = db.rawQuery("select * from information where name=?", new String[]{mEtName.getText().toString()});
                SimpleCursorAdapter spcAdapter = new SimpleCursorAdapter(this, R.layout.list_item, cursor,
                        new String[]{"name", "phone"}, new int[]{R.id.item_name, R.id.item_phone});
                mList.setAdapter(spcAdapter);
            }
            //cursor.close();
            //db.close();
        } else if (id == R.id.btn_update) { //修改数据
            db = myHelper.getWritableDatabase();
            values = new ContentValues();       // 要修改的数据
            values.put("phone", phone = mEtPhone.getText().toString());
            db.update("information", values, "name=?",
                    new String[]{mEtName.getText().toString()}); // 更新并得到行数
            Toast.makeText(this, "信息已修改", Toast.LENGTH_SHORT).show();
            db.close();
        } else if (id == R.id.btn_delete) { //删除数据
            db = myHelper.getWritableDatabase();
            db.delete("information", "name=?", new String[]{mEtName.getText().toString()});
            Toast.makeText(this, mEtName.getText().toString() + "信息已删除", Toast.LENGTH_SHORT).show();
            db.close();
        }
    }
}