Android Sqlite
作者：互联网
DBHelper
package com.example.ex_2;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
public class DbHelper extends SQLiteOpenHelper {
private static final String DATABASE_NAME = "test.db"; //数据库名字
private static final int DATABASE_VERSION = 1 ; //数据库版本号
private static final String TABLE_ = "remark";
private static final String TAG = "mydebug";
//创建 students 表的 sql 语句
private static final String CReate_SQL = "create table if not exists "+
TABLE_ + "("
+ "id integer primary key autoincrement,"
+ "title varchar(100) not null,"
+ "content varchar(1000),"
+ "creat_time datetime not null,"
+ "noti_time datetime not null"
+ ");";
public DbHelper(Context context){
super(context, "test.db", null, 1);
}
/*创建数据库
* id是主键自增*/
@Override
public void onCreate(SQLiteDatabase db) {
Log.d(TAG, "onCreate: ");
db.execSQL(CReate_SQL);
}
/**
* 当检测与前一次创建数据库版本不一样时，先删除表再创建新表
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS " + TABLE_);
onCreate(db);
}
/**
* 变更列名
* @param db
* @param oldColumn
* @param newColumn
* @param typeColumn
*/
public void updateColumn(SQLiteDatabase db, String oldColumn, String newColumn, String typeColumn){
try{
db.execSQL("ALTER TABLE " +
TABLE_ + " CHANGE " +
oldColumn + " "+ newColumn +
" " + typeColumn
);
}catch(Exception e){
e.printStackTrace();
}
}
}
View Code
增删改查
package com.example.ex_2;
import android.content.ContentValues;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.Cursor;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
public class Sql {
private static String TAG = "mydegbug";
private DbHelper dbHelper;
private SQLiteDatabase db;
public Sql(Context context)
{
Log.d(TAG, "Sql: init");
System.out.println("创建数据库");
/* 初始化并创建数据库 */
dbHelper = new DbHelper(context);
// dbHelper.getWritableDatabase();
}
//增
/*
* remark 要存入数据库的实体类
*/
public void add(BeanRemark remark)
{
dbHelper.updateColumn(db, "crea_time", "creat_time", "datetime");
Log.d(TAG, "add: zeng");
db = dbHelper.getWritableDatabase(); //调用SQLiteHelper.OnCreat()
//用容器存储
ContentValues values = new ContentValues();
values.put("title", remark.getTitle());
values.put("content", remark.getContent());
values.put("noti_time", remark.getNoti_time());
values.put("creat_time", remark.getCreat_time());
long result = db.insert("remark", null, values);
db.close();
Log.d(TAG, "add: " + result);
}
//删
//传入要删除对象的id 空的就全删
public void delete(List<String> remarksId) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
Log.d(TAG, "delete: " + remarksId);
int result = 0;
if(!remarksId.isEmpty()) {
for(String Id : remarksId)
result = db.delete("remark", "id = ?", new String[]{Id});
}
else
result = db.delete("remark", null,null);
db.close();
Log.d(TAG, "delete: res = " + result);
}
public void update(BeanRemark remark) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
ContentValues values = new ContentValues();
if(remark.getTitle() != null) values.put("title", remark.getTitle());
if(remark.getContent() != null) values.put("content", remark.getContent());
if(remark.getNoti_time() != null) values.put("noti_time", remark.getNoti_time());
if(remark.getCreat_time() != null)values.put("creat_time", remark.getCreat_time());
int result = db.update("remark", values, "id=?", new String[] {""+remark.getId()});
db.close();
Log.d(TAG, "update: res = " + result);
}
public List<BeanRemark> find(BeanRemark remark) {
SQLiteDatabase db = dbHelper.getWritableDatabase();
List<String> selections = new ArrayList();
List<String> vals = new ArrayList();
//判断 remark 里的哪些量不为空 以此来作为where 条件
if(remark.getId() != -1)
{
selections.add("id = ?");
vals.add((String) (""+remark.getId()));
}
if(remark.getTitle() != null)
{
selections.add("title = ?");
vals.add((String) remark.getTitle());
}
if(remark.getContent() != null)
{
selections.add("content = ?");
vals.add((String) remark.getContent());
}
if(remark.getNoti_time() != null)
{
selections.add("noti_time = ?");
vals.add((String) remark.getNoti_time());
}
if(remark.getCreat_time() != null)
{
selections.add("Creat_time = ?");
vals.add((String) remark.getCreat_time());
}
String selection = new String();
for(int i = 0; i < selections.size(); i++)
{
if(i != 0) selection += "and";
selection += selections.get(i);
}
if(selections.size() > 1)
{
selection += "and";
selection += selections.get(selections.size()-1);
}
Log.d(TAG, "find: " + selection);
Log.d(TAG, "find2: " + vals.toArray(new String[vals.size()]));
Cursor cursor = db.query("remark", null, selection, vals.toArray(new String[vals.size()]), null, null, null);
List<BeanRemark> remarks = new ArrayList<BeanRemark>();
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex("id"));
String title = cursor.getString(cursor.getColumnIndex("title"));
String content = cursor.getString(cursor.getColumnIndex("content"));
String noti_time = cursor.getString(cursor.getColumnIndex("noti_time"));
String creat_time = cursor.getString(cursor.getColumnIndex("creat_time"));
remarks.add(new BeanRemark(id, title, creat_time, noti_time, content));
}
db.close();
return remarks;
}
public List<BeanRemark> findAll()
{
SQLiteDatabase db = dbHelper.getWritableDatabase();
Cursor cursor = db.query("remark", null, null, null, null, null,null);
List<BeanRemark> remarks = new ArrayList<BeanRemark>();
BeanRemark remark = null;
while (cursor.moveToNext()) {
int id = cursor.getInt(cursor.getColumnIndex("id"));
String title = cursor.getString(cursor.getColumnIndex("title"));
String content = cursor.getString(cursor.getColumnIndex("content"));
String noti_time = cursor.getString(cursor.getColumnIndex("noti_time"));
String creat_time = cursor.getString(cursor.getColumnIndex("creat_time"));
remarks.add(new BeanRemark(id, title, creat_time, noti_time, content));
}
db.close();
return remarks;
}
}
View Code
使用
package com.example.ex_2;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;
import java.util.List;
public class Test extends AppCompatActivity {
private static String TAG = "mydebug";
private Sql sql;
private Button btn1,btn2,btn3,btn4;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_test);
sql = new Sql(this);
Log.d(TAG, "onCreate: " + new BeanRemark());
Log.d(TAG, "onCreate: " + sql);
btn1 = findViewById(R.id.zeng);
btn1.setOnClickListener(new mClick());
btn2 = findViewById(R.id.shan);
btn2.setOnClickListener(new mClick());
btn3 = findViewById(R.id.gai);
btn3.setOnClickListener(new mClick());
btn4 = findViewById(R.id.cha);
btn4.setOnClickListener(new mClick());
}
class mClick implements OnClickListener
{
@Override
public void onClick(View arg)
{
switch (arg.getId())
{
case R.id.zeng:
sql.add(new BeanRemark("wang", Time.CurTime(), "2019-12-20 16:32:00","sds"));
sql.add(new BeanRemark("wang", Time.CurTime(), "2019-12-20 16:32:00","sss"));
sql.add(new BeanRemark("li", Time.CurTime(), "2019-12-20 16:32:00","sds"));
Log.d(TAG, "onClick: zeng");
break;
case R.id.shan:
Log.d(TAG, "onClick: shan");
List<BeanRemark> list4 = sql.find(new BeanRemark(null, null, null, "sds"));
List<String> lisId = new ArrayList();
for(BeanRemark item : list4)
lisId.add(""+item.getId());
sql.delete(lisId);
break;
case R.id.gai:
Log.d(TAG, "onClick: gai");
sql.update(new BeanRemark(2,null,null,null,"你是傻逼"));
break;
case R.id.cha:
Log.d(TAG, "onClick: cha");
List<BeanRemark> list = sql.findAll();
Log.d(TAG, "onClick: " + list + "\n");
List<BeanRemark> list2 = sql.find(new BeanRemark(null, null, null, "sds"));
Log.d(TAG, "onClick: " + list2);
List<BeanRemark> list3 = sql.find(new BeanRemark(2,null,null,null,null));
Log.d(TAG, "onClick: find 2 : " + list3);
break;
}
}
}
}
View Code
实体类
package com.example.ex_2;
public class BeanRemark {
private int id = -1;
private String title;
private String creat_time;
private String noti_time;
private String content;
public BeanRemark() {
}
public BeanRemark(int id) {
this.id = id;
}
public BeanRemark(String title, String creat_time, String noti_time, String content) {
this.title = title;
this.creat_time = creat_time;
this.noti_time = noti_time;
this.content = content;
}
public BeanRemark(int id, String title, String creat_time, String noti_time, String content) {
this.id = id;
this.title = title;
this.creat_time = creat_time;
this.noti_time = noti_time;
this.content = content;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getCreat_time() {
return creat_time;
}
public void setCreat_time(String creat_time) {
this.creat_time = creat_time;
}
public String getNoti_time() {
return noti_time;
}
public void setNoti_time(String noti_time) {
this.noti_time = noti_time;
}
public String getContent() {
return content;
}
public void setContent(String content) {
this.content = content;
}
@Override
public String toString() {
return "BeanRemark{" +
"id=" + id +
", title='" + title + '\'' +
", creat_time='" + creat_time + '\'' +
", noti_time='" + noti_time + '\'' +
", content='" + content + '\'' +
'}';
}
}
View Code
标签：remark,String,Sqlite,public,time,Android,null,id 来源： https://www.cnblogs.com/zcfh/p/12076706.html