Android第七次作业

1.建立学生数据库student. db
2.创建学生表stu(id，姓名，年龄)
3.设计注册界面，界面上2个文本框1个按钮(姓名，年龄，注册按钮)
4.实现注册功能（插入)并在sqlite expert perfesonal中查看表数据。
5.更新数据库版本，新增一张表bj(id，班级名)
6.再次在sqlite expert perfesonal中查看表数据。

<?xml version="1.0" encoding="utf-8"?>

<androidx.constraintlayout.widget.ConstraintLayout 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:background="@mipmap/back"

    >

 

    <RelativeLayout

        android:layout_width="match_parent"

        android:layout_height="match_parent">

        <TextView

            android:layout_width="wrap_content"

            android:layout_height="50dp"

            android:layout_marginTop="12dp"

            android:text="姓名"

            android:textColor="#DE9898"

            android:id="@+id/tv1">

        </TextView>

 

        <EditText

            android:id="@+id/et1"

            android:layout_width="200dp"

            android:layout_height="wrap_content"

            android:layout_toRightOf="@id/tv1">

        </EditText>

 

        <TextView

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_marginTop="12dp"

            android:text="年龄"

            android:textColor="#DE9898"

            android:id="@+id/tv2"

            android:layout_below="@id/tv1">

        </TextView>

 

        <EditText

            android:id="@+id/et2"

            android:layout_width="200dp"

            android:layout_height="wrap_content"

            android:layout_below="@id/tv1"

            android:layout_toRightOf="@id/tv2">

        </EditText>

 

        <Button

            android:layout_width="wrap_content"

            android:layout_height="wrap_content"

            android:layout_marginTop="12dp"

            android:text="注册"

            android:textColor="#DE9898"

            android:background="#898888"

            android:layout_below="@id/tv2"

            android:layout_marginHorizontal="135dp"

            android:onClick="click1">

        </Button>

 

    </RelativeLayout>

 

</androidx.constraintlayout.widget.ConstraintLayout>

package com.example.myhomework5;

 

import androidx.appcompat.app.AppCompatActivity;

 

import android.content.ContentValues;

import android.content.Intent;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

import android.view.View;

import android.widget.EditText;

import android.widget.Toast;

 

public class MainActivity extends AppCompatActivity {

 

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        this.setTitle("注册界面");

        StudentDB studentDB = new StudentDB(this);

        studentDB.getWritableDatabase();

    }

 

    public void click1(View view){

        String username = ((EditText)findViewById(R.id.et1)).getText().toString();

        String age = ((EditText)findViewById(R.id.et2)).getText().toString();

        insert(username,age);

        Toast.makeText(MainActivity.this,"注册成功",Toast.LENGTH_LONG).show();

    }

 

    public void insert(String name , String age){

        StudentDB studentDB = new StudentDB(this);

        SQLiteDatabase sqLiteDatabase = studentDB.getWritableDatabase();

        ContentValues contentValues = new ContentValues();

        contentValues.put("name",name);

        contentValues.put("age",age);

        sqLiteDatabase.insert("Stu",null,contentValues);

        sqLiteDatabase.close();

    }

}

package com.example.myhomework5;

 

import android.content.Context;

import android.content.Intent;

import android.database.DatabaseErrorHandler;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

 

import androidx.annotation.Nullable;

 

 

public class StudentDB extends SQLiteOpenHelper{

 

    public StudentDB(Context context) {

        super(context, "stu.db", null, 1);

    }

 

    @Override

    public void onCreate(SQLiteDatabase sqLiteDatabase) {

        String sql = "CREATE TABLE Stu(id INTEGER PRIMARY KEY autoincrement, NAME VARCHAR(20), age VARCHAR(10))";

        sqLiteDatabase.execSQL(sql);

 

    }

 

    @Override

    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

 

    }

}

package com.example.myhomework5;

 

import android.content.Context;

import android.content.Intent;

import android.database.DatabaseErrorHandler;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteOpenHelper;

 

import androidx.annotation.Nullable;

 

 

public class StudentDB extends SQLiteOpenHelper{

 

    public StudentDB(Context context) {

        super(context, "stu.db", null, 3);

    }

 

    @Override

    public void onCreate(SQLiteDatabase sqLiteDatabase) {

        String sql = "CREATE TABLE Stu(id INTEGER PRIMARY KEY autoincrement, NAME VARCHAR(20), age VARCHAR(10))";

        sqLiteDatabase.execSQL(sql);

 

    }

     

    // 数据库版本更新被调用,版本只能升不能降

    @Override

    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

        String sql2 = "CREATE TABLE bj(id INTEGER PRIMARY KEY autoincrement, Class_NAME VARCHAR(20))";

        sqLiteDatabase.execSQL(sql2);

    }

}