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SQLite的简单使用

工具：

1. android studio
2. SQLite 3
   
   至于以上两种工具的下载以及安装，可以自行百度

首先打开android studio 创建一个新项目



以下模板中随便一个都行，在这里我选择了Empty Activity，取名任意。



先运行一下结果是这样的：

就是一个空白页，接下来我们让他实现从SQLite读取数据的功能，代码如下:

MainActivity.java

package com.example.sqlitetestdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    static final String db_name = "testDatabase";
    static final String tb_name = "testTable";
    SQLiteDatabase db;

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

        //数据库操作
        db = openOrCreateDatabase(db_name, Context.MODE_PRIVATE, null);
        String createTable = "CREATE TABLE IF NOT EXISTS " +
                tb_name +
                "(name VARCHAR(32), " +
                "birth_and_age VARCHAR(60), " +
                "job_date VARCHAR(60), " +
                "dang_date VARCHAR(60), " +
                "message VARCHAR(100))";
        db.execSQL(createTable);

        Cursor c = db.rawQuery("SELECT * FROM "+tb_name,null);

        //若数据库表中没有数据，则新增一条数据
        if(c.getCount() == 0){
            db.execSQL("INSERT INTO testTable VALUES('张三','1962.12出生，53岁，汉族','1984.08参加工作','1983.04中共党员','2011.12任现值')");
            c = db.rawQuery("SELECT * FROM "+tb_name,null);
        }
        if(c.moveToFirst()) {
            String str1,str2,str3,str4,str5;
            str1 = c.getString(0);
            str2 = c.getString(1);
            str3 = c.getString(2);
            str4 = c.getString(3);
            str5 = c.getString(4);
            TextView textView1 = (TextView) findViewById(R.id.textView2);
            TextView textView2 = (TextView) findViewById(R.id.textView3);
            TextView textView3 = (TextView) findViewById(R.id.textView4);
            TextView textView4 = (TextView) findViewById(R.id.textView5);
            TextView textView5 = (TextView) findViewById(R.id.textView6);
            textView1.setText(str1);
            textView2.setText(str2);
            textView3.setText(str3);
            textView4.setText(str4);
            textView5.setText(str5);
        }
        db.close();
    }
}

activity_main.xml

<?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">

    <TextView
        android:id="@+id/textView4"
        android:layout_width="235dp"
        android:layout_height="21dp"
        android:layout_marginTop="132dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:id="@+id/textView5"
        android:layout_width="235dp"
        android:layout_height="21dp"
        android:layout_marginTop="168dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:id="@+id/textView6"
        android:layout_width="235dp"
        android:layout_height="21dp"
        android:layout_marginStart="2dp"
        android:layout_marginLeft="2dp"
        android:layout_marginTop="202dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="79dp"
        android:layout_height="21dp"
        android:layout_marginTop="62dp"
        android:text="姓名"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="87dp"
        android:layout_height="21dp"
        android:layout_marginStart="97dp"
        android:layout_marginLeft="97dp"
        android:layout_marginTop="62dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="235dp"
        android:layout_height="21dp"
        android:layout_marginStart="2dp"
        android:layout_marginLeft="2dp"
        android:layout_marginTop="96dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        tools:ignore="MissingConstraints" />

</androidx.constraintlayout.widget.ConstraintLayout>

一个activity.java对应一个activity.xml文件，相当于一个控制器对应一个视图，这有些类似于spring mvc的逻辑。

这是视图:





最后点击上图的三角运行，运行结果如下图: