安卓數據庫——SQLite使用

在這里插入圖片描述

1.建數據庫，數據庫適配器，寫增刪改查方法：

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

import java.util.ArrayList;
import java.util.List;

public class MySQLiteOpenHelper extends SQLiteOpenHelper {
public MySQLiteOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
super(context, name, factory, version);
}
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(“msg”,“創建數據庫”);
String createStr = “create table student (id integer primary key autoincrement not null,” +
“name varchar not null,” +
“tell varchar not null,” +
“address varchar not null)”;
db.execSQL(createStr);

//插入學生信息
public void insert(String tableNm, Student student) {
    SQLiteDatabase sql = getWritableDatabase();
    ContentValues values = new ContentValues();
    values.put("name", student.getName());
    values.put("tell", student.getTell());
    values.put("address", student.getAddress() );
    sql.insert(tableNm, null, values);
}
public void delete(String tableNm, int id) {
    SQLiteDatabase sql = getWritableDatabase();
    String where = "id=?";
    sql.delete(tableNm, where, new String[]{id + ""});
}

public List selectAll(String tableNm) {
List students = new ArrayList<>();
SQLiteDatabase database = getReadableDatabase();
String selectstr = “select * from " + tableNm;
Cursor cursor = database.rawQuery(selectstr, null);
// Cursor cursor=database.query(tableNm,new String[]{“id”,“name”,“age”,“sex”},null,null,null,null,null);
cursor.moveToFirst();
do {
int id = cursor.getInt(cursor.getColumnIndex(“id”));
String name = cursor.getString(cursor.getColumnIndex(“name”));
String tell = cursor.getString(cursor.getColumnIndex(“tell”));
String address = cursor.getString(cursor.getColumnIndex(“address”));
students.add(new Student(id, name, tell, address));
}
while (cursor.moveToNext());
return students;
}
public void update(String tableNm,ContentValues values,int id)
{
SQLiteDatabase database = getWritableDatabase();
// String where = “id = ?”;
// database.update(tableNm,values,where,new String[]{id+”"});
// UPDATE newTable SET id = 0, name = ‘’, age = 0, sex = ‘’ WHERE id = ;
String sql = “update “+tableNm+” set name=?,tell=?,address=? where id = ?”;
database.execSQL(sql,new String[]{values.get(“name”).toString(),values.get(“tell”).toString(),values.get(“address”).toString(),id+""})
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

2.寫參數，建bean類
public class Student {
private int id;
private String name;
private String tell;
private String address;

public Student() {
}

public Student(String name, String tell, String address) {
    this.name = name;
    this.tell = tell;
    this.address = address;
}

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 getTell() {
    return tell;
}

public void setTell(String tell) {
    this.tell = tell;
}

public String getAddress() {
    return address;
}

public void setAddress(String address) {
    this.address = address;
}

@Override
public String toString() {
    return "Student{" +
            "id=" + id +
            ", name='" + name + '\'' +
            ", tell='" + tell + '\'' +
            ", address='" + address + '\'' +
            '}';
}

public Student(int id, String name, String tell, String address) {
    this.id = id;
    this.name = name;
    this.tell = tell;
    this.address = address;
}

}

3. mainactivity中的代碼

import android.content.ContentValues;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.RadioButton;
import android.widget.TextView;

import java.util.List;

public class MainActivity extends AppCompatActivity {
ListView lv;
private MySQLiteOpenHelper helper;
static String student_table = “student”;
Button ad_del,ad_xiu,main_add;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//數據庫表名，版本號
helper = new MySQLiteOpenHelper(getApplicationContext(), “studentdb”, null, 1);
lv=findViewById(R.id.lv);
ad_xiu=findViewById(R.id.ad_xiu);
ad_del=findViewById(R.id.ad_del);
main_add=findViewById(R.id.main_add);
//查詢全部并顯示到listview中
List SJ=helper.selectAll(student_table);
lv.setAdapter(new lvAdapter(SJ));
//點擊跳轉
main_add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent intent=new Intent(MainActivity.this,ADDActivity.class);
startActivity(intent);
}
});
}

//listview適配器
class lvAdapter extends BaseAdapter {
private List students;
//傳參類型
public lvAdapter(List students) {
this.students = students;
}

    @Override
    public int getCount() {
        return students.size();
    }

    @Override
    public Object getItem(int position) {
        return students.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view;
        if (convertView == null) {
            //把查詢數據填到listview 的item中
            view = LayoutInflater.from(getApplicationContext()).inflate(R.layout.lv_layout, null);
            Student student = students.get(position);
            TextView txt = view.findViewById(R.id.ad_name);
            txt.setText(student.getName());
            txt = view.findViewById(R.id.ad_tell);
            txt.setText(student.getTell());
            txt = view.findViewById(R.id.ad_adress);
            txt.setText(student.getAddress() + "");

        } else {
            view = convertView;
        }
        return view;
    }
}

}

*4.main布局：

5.跳轉界面：
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.RadioButton;
import android.widget.TextView;

public class ADDActivity extends AppCompatActivity {
EditText add_name,add_tel,add_adress;
private MySQLiteOpenHelper helper;
static String student_table = “student”;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_add);
helper = new MySQLiteOpenHelper(getApplicationContext(), “studentdb”, null, 1);
add_name=findViewById(R.id.add_name);
add_tel=findViewById(R.id.add_tel);
add_adress=findViewById(R.id.add_address);
Button btn=findViewById(R.id.add_qd);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String name = add_name.getText().toString();
String tel=add_tel.getText().toString();
String address=add_adress.getText().toString();
helper.insert(“student”, new Student(name, tel, address));
Intent intent=new Intent(ADDActivity.this,MainActivity.class);
startActivity(intent);
}
});
}
}

6.跳轉界面布局：

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

listview布局

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

<TextView
    android:id="@+id/ad_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="邱國忠"
    android:textSize="25dp"
    />
<TextView
    android:id="@+id/ad_tell"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_toRightOf="@id/ad_name"
    android:text="15770836531"
    android:textSize="22dp"
    android:layout_margin="2dp"
    />
<TextView
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="學校"
    android:layout_toRightOf="@id/ad_tell"
    android:layout_marginRight="3dp"
    android:layout_marginTop="5dp"
    />
<TextView
    android:id="@+id/ad_adress"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="紅紅火火恍恍惚惚哈哈"
    android:textSize="20dp"
    android:layout_below="@id/ad_name"/>
<RadioButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="設為默認"

    android:layout_below="@id/ad_adress"/>
<Button
    android:id="@+id/ad_xiu"
    android:layout_width="55dp"
    android:layout_height="35dp"
    android:text="編輯"

    android:layout_toLeftOf="@id/ad_del"
    android:layout_below="@id/ad_adress"
    />
<Button
    android:id="@+id/ad_del"
    android:layout_width="55dp"
    android:layout_height="35dp"
    android:text="刪除"
    android:layout_alignParentRight="true"
    android:layout_below="@id/ad_adress"
    />

本文鏈接：https://blog.csdn.net/weixin_44827506/article/details/101152386

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