Litepal使用

在build.gradle里面添加下面依赖

dependencies {
    implementation 'org.litepal.guolindev:core:3.2.3'

}

在AndroidManifest.xml配置LitePalApplication

    ...
    

遇到litepal.LitePalApplication爆红解决：

在settings.gradle添加箭头指向的代码：

新建assets目录，在assets目录下面新建一个litepal.xml文件，加入以下配置

import org.litepal.crud.LitePalSupport;

public class Students extends LitePalSupport {

    private int id;
    private String name;
    //需要生成get set方法
}

所有实体类都需要继承LitePalSupport 

SQLiteDatabase db = Connector.getDatabase();

也可以不使用该语句，因为只要你对数据库有任何的操作，相对应的表就会被自动创建出来。

                Students students=new Students();
                students.setName(String.valueOf(editText.getText()));
                if (students.save()) {
                    Toast.makeText(this, "存储成功", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(this, "存储失败", Toast.LENGTH_SHORT).show();
                }

                //删除指定id的数据
                LitePal.delete(Students.class,Integer.parseInt(String.valueOf(editText.getText())));
                //删除表中所以数据
                LitePal.deleteAll(Students.class);
                //删除所以name为指定值的数据
                LitePal.deleteAll(Students.class,"name=?", String.valueOf(editText.getText()));

                //更改第一条字段为name的数据，将name改为输入的name
                ContentValues contentValues=new ContentValues();
                contentValues.put("name", String.valueOf(editText.getText()));
                LitePal.update(Students.class,contentValues,1);
                //修改全部name为指定值的数据(将name为123的数据全改为输入的name)
                ContentValues contentValues=new ContentValues();
                contentValues.put("name", String.valueOf(editText.getText()));
                LitePal.updateAll(Students.class,contentValues,"name=?", "123");
                //修改全部name数据为输入数据
                ContentValues contentValues=new ContentValues();
                contentValues.put("name", String.valueOf(editText.getText()));
                LitePal.updateAll(Students.class,contentValues);

                //单语句查询
                Students students1= LitePal.find(Students.class,Integer.parseInt(String.valueOf(editText.getText())));
                    textView.setText(students1.getId()+","+students1.getName());
                //所以语句查询
                List students2=LitePal.findAll(Students.class);
                System.out.println(students2.toString());
                textView.setText(students2.toString());

当实体类发生改变时，表的结构也需要同时改变：

 将数据库版本号在原来的基础上+1就会更新表。

package com.example.lab5exer01;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.ContentValues;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import org.litepal.LitePal;
import org.litepal.crud.LitePalSupport;

import java.util.List;

public class MainActivity extends AppCompatActivity {

    TextView textView;
    EditText editText;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textView=findViewById(R.id.text);
        editText=findViewById(R.id.text1);
        Button button1=findViewById(R.id.buttob1);
        Button button2=findViewById(R.id.buttob2);
        Button button3=findViewById(R.id.buttob3);
        Button button4=findViewById(R.id.buttob4);
        button1.setOnClickListener(this::onclick);
        button2.setOnClickListener(this::onclick);
        button3.setOnClickListener(this::onclick);
        button4.setOnClickListener(this::onclick);
    }

    @SuppressLint({"NonConstantResourceId", "SetTextI18n"})
    private void onclick(View view) {
        switch (view.getId()){
            case R.id.buttob1:
                Students students=new Students();
                students.setName(String.valueOf(editText.getText()));
                if (students.save()) {
                    Toast.makeText(this, "存储成功", Toast.LENGTH_SHORT).show();
                } else {
                    Toast.makeText(this, "存储失败", Toast.LENGTH_SHORT).show();
                }

                Log.d("TAG", "news id is " + students.getId());
                break;

            case R.id.buttob2:
                //删除指定id的数据
                LitePal.delete(Students.class,Integer.parseInt(String.valueOf(editText.getText())));
                
                
                break;

            case R.id.buttob3:
                
                //修改全部name为指定值的数据
                ContentValues contentValues=new ContentValues();
                contentValues.put("name", String.valueOf(editText.getText()));
                LitePal.updateAll(Students.class,contentValues,"name=?", "123");
                
                break;

            case R.id.buttob4:
                //单语句查询
                Students students1= LitePal.find(Students.class,Integer.parseInt(String.valueOf(editText.getText())));
                if(students1!=null){
                    textView.setText(students1.getId()+","+students1.getName());
                }else {
                    textView.setText("没有该数据");
                }


                
                break;

        }
    }


}

package com.example.lab5exer01;

import org.litepal.crud.LitePalSupport;

public class Students extends LitePalSupport {

    public String getName() {
        return name;
    }

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

    @Override
    public String toString() {
        return "Students{" +
                "id=" + id +
                ", name='" + name + ''' +
                '}';
    }

    public int getId() {
        return id;
    }

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

    private int id;
    private String name;


}