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android SQLite 使用

https://www.cnblogs.com/ljy-1471914707/p/5444531.html

package com.example.sql1;

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

import androidx.annotation.Nullable;

public class Person extends SQLiteOpenHelper {

    public static final String CREATE_BOOK = "create table person("
            + "_id integer primary key autoincrement, "
            + "name text, "
            + "tel text)";

    public Person(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL(CREATE_BOOK);
    }

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

    }
}

package com.example.sql1;

import androidx.appcompat.app.AppCompatActivity;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    Button btn_add = null;
    Button btn_delete = null;
    Button btn_update = null;
    Button btn_search = null;
    EditText edit_name = null;
    EditText edit_tel = null;
    TextView txt_result = null;
    Person personHelper = null;
    SQLiteDatabase db;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        personHelper = new Person(this, "personDB.db", null, 1);//new一个类，注意*.db不能跟类重名
        btn_add = (Button) findViewById(R.id.btn_add);
        btn_delete = (Button) findViewById(R.id.btn_delete);
        btn_search = (Button) findViewById(R.id.btn_search);
        btn_update = (Button) findViewById(R.id.btn_update);
        edit_name = (EditText) findViewById(R.id.edit_name);
        edit_tel = (EditText) findViewById(R.id.edit_number);
        txt_result = (TextView) findViewById(R.id.txt_result);
        txt_result.setMovementMethod(new ScrollingMovementMethod());  //使得内容多时textview可以滚动

        db = personHelper.getWritableDatabase();
        btn_add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String str_name = edit_name.getText().toString();
                String str_tel = edit_tel.getText().toString();
//                ContentValues cv = new ContentValues();
//                cv.put("name", str_name);
//                cv.put("tel", str_tel);
//                db.insert("person",null,cv);
                String sql = "insert into person (name,tel) values (?,?)";
                Object[] args = {str_name,str_tel};
                db.execSQL(sql,args); //无返回值
                Log.e("sql", str_name);
                Log.e("sql", str_tel);
            }

        });

        btn_search.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String result = "";
                String sql ="select * from person";
                Cursor cursor = db.rawQuery(sql, null);
                cursor.moveToFirst();
                if (cursor.moveToFirst()){
                    do{
                        int id = cursor.getInt(0);
                        String nameString = cursor.getString(1);
                        String telString = cursor.getString(2);
                        result += "id="+id+"    name:"+nameString+"        tel:"+telString+"
";
                        Log.d("sql", nameString);
                        //Log.d("sql", id);
                        Log.e("sql", telString);
                    }while(cursor.moveToNext());
                }
                cursor.close();
                txt_result.setText(result);
            }
        });


        btn_delete.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String str_name = edit_name.getText().toString();
                String str_tel = edit_tel.getText().toString();
              //  db.delete("person", "name=? and tel=?", new String[]{str_name,str_tel});
                String sql = "delete from person where name = "+str_name +" and " + "tel=" + str_tel;
                db.execSQL(sql);

            }
        });
        btn_update.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String str_name = edit_name.getText().toString();
                String str_tel = edit_tel.getText().toString();
              //  ContentValues cv = new ContentValues();
              //  cv.put("tel", str_tel);
              //  db.update("person", cv, "name=?", new String[]{str_name});

                String sql = "update person set tel=? where name=?";
                Object[] args = {str_tel,str_name};
                db.execSQL(sql,args);

            }
        });

    }
}

<?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">

    <TextView
        android:id="@+id/txt_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="20dp"
        android:text="@string/name"
        android:textSize="20sp" />

    <EditText
        android:id="@+id/edit_name"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/txt_name"
        android:layout_alignBottom="@+id/txt_name"
        android:layout_marginLeft="21dp"
        android:layout_toRightOf="@+id/txt_name"
        android:ems="10"
        android:inputType="textPersonName" />

    <EditText
        android:id="@+id/edit_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/txt_number"
        android:layout_alignLeft="@+id/edit_name"
        android:ems="10"
        android:inputType="number" />

    <TextView
        android:id="@+id/txt_number"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/edit_name"
        android:layout_marginTop="18dp"
        android:layout_toLeftOf="@+id/edit_name"
        android:text="@string/phonenumber"
        android:textSize="20sp" />

    <ScrollView
        android:id="@+id/scrollView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/btn_update"
        android:layout_below="@+id/btn_update" >
    </ScrollView>

    <Button
        android:id="@+id/btn_add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignRight="@+id/edit_number"
        android:layout_below="@+id/edit_number"
        android:layout_marginRight="47dp"
        android:text="@string/add" />

    <Button
        android:id="@+id/btn_delete"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/btn_update"
        android:layout_toRightOf="@+id/txt_number"
        android:text="@string/delete" />

    <TextView
        android:id="@+id/txt_result"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_alignTop="@+id/scrollView1"
        android:layout_toRightOf="@+id/txt_number"
        android:maxLines = "1000"
    android:scrollbars = "vertical"
    android:text="@string/result" />

    <Button
        android:id="@+id/btn_update"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/btn_add"
        android:layout_below="@+id/btn_add"
        android:layout_marginTop="16dp"
        android:text="@string/update" />

    <Button
        android:id="@+id/btn_search"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_above="@+id/txt_result"
        android:layout_alignLeft="@+id/txt_result"
        android:text="@string/search" />

</RelativeLayout>

可以进行一次封装，把数据库操作封装成一个类。在activity直接调用数据库类，进行操作。

package com.example.sql1;

public class personData {
    private int id;

    public personData(int id, String name, String tel) {
        this.id = id;
        this.name = name;
        this.tel = tel;
    }

    private String name;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getTel() {
        return tel;
    }

    public void setTel(String tel) {
        this.tel = tel;
    }

    private String tel;




}

View Code

package com.example.sql1;

import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;

public  class PersonDao {
    private static SQLiteDatabase db;
    Person personHelper = null;

    public PersonDao(Context ctx) {

    personHelper =new Person(ctx, "personDB.db",null,1);//new一个类，注意*.db不能跟类重名
    db = personHelper.getWritableDatabase();

}
    static void add(personData data){
        //        ContentValues cv = new ContentValues();
//                cv.put("name", str_name);
//                cv.put("tel", str_tel);
//                db.insert("person",null,cv);

        String sql = "insert into person (name,tel) values (?,?)";
        Object[] args = {data.getName(),data.getTel()};
        db.execSQL(sql,args); //无返回值

    }
    static void delete(String name,String tel){
        //db.delete("person", "name=? and tel=?", new String[]{name,tel});
      //  String sql = "delete from person where name ="+name +" and " + "tel=" + tel;
        String sql = "delete from person where name =? and tel = ?";
        Object[] args = {name,tel};
        db.execSQL(sql,args);

    }
    static void deleteAll(){
        //  db.delete("person", "name=? and tel=?", new String[]{str_name,str_tel});
        String sql = "delete from person ";
        db.execSQL(sql);

    }

    static void update(personData data){
        //  ContentValues cv = new ContentValues();
        //  cv.put("tel", str_tel);
        //  db.update("person", cv, "name=?", new String[]{str_name});


        String sql = "update person set name=? where tel=?";
        Object[] args = {data.getName(),data.getTel()};
        db.execSQL(sql,args);

    }

    static public Cursor getData(){
        String sql ="select * from person";
        Cursor cursor = db.rawQuery(sql, null);
        return cursor;
    }

}

View Code

package com.example.sql1;

import androidx.appcompat.app.AppCompatActivity;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.text.method.ScrollingMovementMethod;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    Button btn_add = null;
    Button btn_delete = null;
    Button btn_update = null;
    Button btn_search = null;
    EditText edit_name = null;
    EditText edit_tel = null;
    TextView txt_result = null;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        PersonDao personDao = new PersonDao(this);//new一个类，注意*.db不能跟类重名
        btn_add = (Button) findViewById(R.id.btn_add);
        btn_delete = (Button) findViewById(R.id.btn_delete);
        btn_search = (Button) findViewById(R.id.btn_search);
        btn_update = (Button) findViewById(R.id.btn_update);
        edit_name = (EditText) findViewById(R.id.edit_name);
        edit_tel = (EditText) findViewById(R.id.edit_number);
        txt_result = (TextView) findViewById(R.id.txt_result);
        txt_result.setMovementMethod(new ScrollingMovementMethod());  //使得内容多时textview可以滚动


        btn_add.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String str_name = edit_name.getText().toString();
                String str_tel = edit_tel.getText().toString();
                if(!str_name.isEmpty() || !str_tel.isEmpty()){
                    personData data = new personData(1,str_name,str_tel);
                    PersonDao.add(data);
                }else{
                    Log.e("sql", "no data");
                }

            }

        });

        btn_search.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String result = "";

                Cursor cursor = PersonDao.getData();
                cursor.moveToFirst();
                if (cursor.moveToFirst()){
                    do{
                        int id = cursor.getInt(0);
                        String nameString = cursor.getString(1);
                        String telString = cursor.getString(2);
                        result += "id="+id+"    name:"+nameString+"        tel:"+telString+"
";
                       // Log.e("sql", nameString);
                      //  Log.e("sql", telString);
                    }while(cursor.moveToNext());
                }
                cursor.close();
                txt_result.setText(result);
            }
        });


        btn_delete.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String str_name = edit_name.getText().toString();
                String str_tel = edit_tel.getText().toString();

                PersonDao.delete(str_name,str_tel);
               // PersonDao.deleteAll();
            }
        });
        btn_update.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                String str_name = edit_name.getText().toString();
                String str_tel = edit_tel.getText().toString();

                personData data = new personData(1,str_name,str_tel);
                PersonDao.update(data);
            }
        });


    }
}

View Code

package com.example.sql1;

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

import androidx.annotation.Nullable;

public class Person extends SQLiteOpenHelper {

    public static final String CREATE_BOOK = "create table person("
            + "_id integer primary key autoincrement, "
            + "name text, "
            + "tel text)";

    public Person(@Nullable Context context, @Nullable String name, @Nullable SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL(CREATE_BOOK);
    }

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

    }

}

View Code

static public Cursor getOneData(int id){

　　String sql ="select * from person where _id = ?";

　　String[]args = {Integer.toString(id)};

　　Cursor cursor = db.rawQuery(sql, args );

　　return cursor;

}

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原文地址：https://www.cnblogs.com/yuguangyuan/p/13263194.html