Android考勤系统笔记（一）：SQLite数据库实现员工增删改查

简单的增删改查操作

最近一段时间完善了人脸识别考勤系统，做得大部分功能都比较简单，这里写一些笔记做一下记录。期间参考资料太多……也不记得参考过哪些博文，有些比较好的笔记，后期再贴出来

先写一下最基础的功能，对员工的增删改查操作。
先看一下界面，后面贴上主要代码，布局就不贴啦
后面等项目都完成，再上传整个项目源码

因为硬件配的屏幕是横版的所以界面就做横版了

员工实体类
EmployeeInfo.class

/*
 *@Author:Swallow
 *@Date:2019/2/22
 * 存放员工
 */
public class EmployeeInfo {
    private String emid;
    private String emname;
    private String imgurl;

    public EmployeeInfo() {
    }

    public EmployeeInfo(String emid, String emname, String imgurl) {
        this.emid = emid;
        this.emname = emname;
        this.imgurl = imgurl;
    }

    public String getEmid() {
        return emid;
    }

    public void setEmid(String emid) {
        this.emid = emid;
    }

    public String getEmname() {
        return emname;
    }

    public void setEmname(String emname) {
        this.emname = emname;
    }

    public String getImgurl() {
        return imgurl;
    }

    public void setImgurl(String imgurl) {
        this.imgurl = imgurl;
    }

    @Override
    public String toString() {
        return "EmployeeInfo{" +
                "emid=" + emid +
                ", emname='" + emname + '\'' +
                ", imgurl='" + imgurl + '\'' +
                '}';
    }
}

有做数据存储的，我习惯写一个类存放常用字段，这样平时写不容易写错
EmployeeTable.class

/*
 *@Author:Swallow
 *@Date:2019/2/22
 */
public class EmployeeTable {

    public static final String TAB_NAME = "tab_employee";
    public static final String EM_ID = "emid";
    public static final String EM_NAME = "emname";
    public static final String EM_URL = "imgurl";

    public static final String CREATE_TAB = "create table if not exists "
            + TAB_NAME + " ("
            + EM_ID + " VARCHAR(255) primary key,"
            + EM_NAME + " VARCHAR(255),"
            + EM_URL + " VARCHAR(255));";
}

然后是操作处理用到的DAO类，这个比较重要，方法封装进来，直接调用就行

EmployeeDao.class

/*
 *@Author:Swallow
 *@Date:2019/2/25
 */
public class EmployeeDao {
    private DBHelper dbHelper;
    private SQLiteDatabase sqliteDatabase;

    public EmployeeDao(Context context) {
        dbHelper = new DBHelper(context,"Data.db",null,1);
    }

    //根据工号查询
    public  EmployeeInfo  findemployeebyid(String emid){
        sqliteDatabase = dbHelper.getWritableDatabase();
        String sql = "select * from " + EmployeeTable.TAB_NAME + " where emid=?";
        String[] selectionArgs = new String[] { emid };
        Cursor cursor = sqliteDatabase.rawQuery(sql, selectionArgs);
        if(cursor.moveToNext())// 判断Cursor中是否有数据
        {
            EmployeeInfo employee = new EmployeeInfo();
            employee.setEmid(cursor.getString(cursor.getColumnIndex(EmployeeTable.EM_ID)));
            employee.setEmname(cursor.getString(cursor.getColumnIndex(EmployeeTable.EM_NAME)));
            employee.setImgurl(cursor.getString(cursor.getColumnIndex(EmployeeTable.EM_URL)));
            Log.v("imgpath>>>>>>",employee.getImgurl());
            return employee;
        }
        return null;
    }
    
    //添加员工信息
    public void addEmployee(String emid, String emname, String imgurl) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(EmployeeTable.EM_ID,emid);
        values.put(EmployeeTable.EM_NAME,emname);
        values.put(EmployeeTable.EM_URL,imgurl);
        db.insert(EmployeeTable.TAB_NAME,null,values);
        db.close();
    }

//根据员工编号检验员工是否存在
public boolean CheckIsDataAlreadyInDBorNot(String emid) {
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        String Query = "Select * from " + EmployeeTable.TAB_NAME +  " where emid =?";
        Cursor cursor = db.rawQuery(Query, new String[]{emid});
        if (cursor.getCount() > 0) {
            cursor.close();
            return true;
        }
        cursor.close();
        return false;
    }
//下面两个方法返回一个ArrayList>对象，是为了方便调用的时候数据传给listView进行展示
//根据输入的员工工号进行查找,查找单个员工
    private ArrayList> findemployeebyid(String getemid) {
        //String etemid = et_findbyemid.getText().toString();//获取输入的员工工号
        ArrayList> employees = new ArrayList>();

            SQLiteDatabase db = dbHelper.getReadableDatabase();//设置数据库为可读
            String findsql = "select * from " + EmployeeTable.TAB_NAME + " where emid=?";
            Cursor cursor = db.rawQuery(findsql,new String[]{getemid});
            if(cursor.moveToNext())// 判断Cursor中是否有数据
            {
                String emid = cursor.getString(0);
                String emname = cursor.getString(1);
                HashMap hash = new HashMap();
                hash.put("emid",emid);
                hash.put("emname",emname);
                employees.add(hash);

            }else {
                return null;
            }
        return employees;
    }

    //查询所有员工

    private ArrayList> Getemployees(String sql) {
        ArrayList> employeelist = new ArrayList>();
        ArrayList employeeInfos = new ArrayList<>();

        //dbHelper = new DBHelper(this,"Data.db",null,1);
        SQLiteDatabase db = dbHelper.getReadableDatabase();
        Cursor cursor = db.rawQuery(sql,null);
        while (cursor.moveToNext()){
            HashMap hash = new HashMap();
            //读取数据并且进行封装
            String emid = cursor.getString(0);
            String emname = cursor.getString(1);
            hash.put("emid",emid);
            hash.put("emname",emname);
            employeelist.add(hash);
            Log.v("list>>>>>",emid + emname);
        }
        return employeelist;
    }
//删除员工
	public void deleteEmployee(String emid){
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        String sql = "delete from " + EmployeeTable.TAB_NAME + " where emid=?";
        db.execSQL(sql,new String[]{emid});
    }
    
    //修改员工信息，这里我设定的是工号不可修改，根据工号修改员工的姓名和照片

    public void updataEmployee(String id,String name,String path){
        SQLiteDatabase db = dbHelper.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(EmployeeTable.EM_URL, path);
        values.put(EmployeeTable.EM_NAME, name);
        db.update(EmployeeTable.TAB_NAME, values,"emid='" + id +"'",null);
        //id是String类型，设置条件句要用 ' ' 包围
        db.close();
    }
}

另外，当时有一个坑，挺坑的
就是传入的sql语句一定要注意写得全不全，之前我就是少了个单引号折腾很久
一开始看别人写的传入的String类型没有单引号包围，但实际上是要写的，如果是int类型就可以不用

展示员工列表界面的Activity类

import android.app.Activity;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.inputmethod.InputMethodManager;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.LinearLayout;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

import com.taixueface.bean.EmployeeInfo;
import com.taixueface.dao.EmployeeDao;
import com.taixueface.dao.EmployeeTable;

import java.util.ArrayList;
import java.util.HashMap;

public class ManageActivity extends Activity implements View.OnClickListener {
    
    private EditText et_findbyemid;
    private ImageButton btn_findbyemid;
    private Button btn_record,btn_addem,btn_set,btn_back;
    private LinearLayout ly_manage;
    private ListView lv_employee;
    private EmployeeDao employeeDao;

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

        init();
        String selectsql = "select * from " + EmployeeTable.TAB_NAME + ";";
        showlist(selectsql);

        //设置点击List当中的某一项跳转到新界面的监听
        //新界面为该员工的详细信息界面MessageActivity
        lv_employee.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView adapterView, View view, int arg0, long arg1) {
                Log.v("arg0>>>>>>", String.valueOf(arg0));
                HashMap hashMap = (HashMap) adapterView.getItemAtPosition(arg0);
                final String emid = hashMap.get(EmployeeTable.EM_ID).toString() ;
                Log.v("click get>>>>>>>>>  ", emid);
                //获取点击信息传递到下一个页面
                Bundle bundle = new Bundle();
                bundle.putString(EmployeeTable.EM_ID,emid);
                Intent msg_intent = new Intent();
                msg_intent.putExtras(bundle);
                msg_intent.setClass(ManageActivity.this,MessageActivity.class);
                startActivity(msg_intent);
            }
        });

        lv_employee.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView arg0, View arg1, int arg2, final long arg3) {

                //长按弹出提示框进行删除数据操作
                HashMap hm = (HashMap) arg0.getItemAtPosition(arg2);
                final String emid = hm.get("emid").toString();// 长按时获取id，赋值给id
                Log.v("longgetemid>>>>>>>>>  ", emid);
                AlertDialog.Builder builder=new AlertDialog.Builder(ManageActivity.this);
                builder.setMessage("是否删除该员工信息？");
                builder.setTitle("提示");

                //设置确定按钮的监听器，以下为删除操作
                builder.setPositiveButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {
                        employeeDao.deleteEmployee(emid);
                        String afteraql = "select * from " + EmployeeTable.TAB_NAME + ";";
                        showlist(afteraql);
                        //Log.v("id>>>>>",i+ "long" + l);
                    }
                });
                builder.setNegativeButton("取消", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialogInterface, int i) {

                    }
                });

                builder.create().show();
                return false;
            }
        });

    }

//初始化控件
    private void init() {
        et_findbyemid = findViewById(R.id.et_findbyemid);
        btn_findbyemid = findViewById(R.id.btn_findbyemid);
        btn_record = findViewById(R.id.btn_record);
        btn_addem = findViewById(R.id.btn_addem);
        btn_set = findViewById(R.id.btn_set);
        btn_back = findViewById(R.id.btn_back);
        lv_employee = findViewById(R.id.lv_employee);
        ly_manage = findViewById(R.id.ly_manage);
        ly_manage.setOnClickListener(this);

        btn_findbyemid.setOnClickListener(this);
        btn_record.setOnClickListener(this);
        btn_addem.setOnClickListener(this);
        btn_set.setOnClickListener(this);
        btn_back.setOnClickListener(this);

    }

    @Override
    public void onClick(View view) {
        switch (view.getId()){
            case R.id.btn_back:
                Intent back_intent = new Intent(this,MainActivity.class);
                startActivity(back_intent);
                break;

            case R.id.ly_manage:
                InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
                imm.hideSoftInputFromWindow(view.getWindowToken(), 0);
                break;

            case R.id.btn_findbyemid:
                checkEmployee();
                break;

            case R.id.btn_record:
                Intent record_intent = new Intent(ManageActivity.this,
                        RecordActivity.class);
                startActivity(record_intent);
                break;

            case R.id.btn_addem:
                Intent add_intent = new Intent(ManageActivity.this,
                        AddActivity.class);
                startActivity(add_intent);
                break;

            case R.id.btn_set:
                Intent set_intent = new Intent(ManageActivity.this,
                        SetActivity.class);
                startActivity(set_intent);
                break;

        }
    }

    //根据输入的员工工号进行查找
    private void checkEmployee() {
        String etemid = et_findbyemid.getText().toString();//获取输入的员工工号
        if(!etemid.isEmpty()){
            ArrayList> employees = employeeDao.findemployeebyid(etemid);
            if(!employees.isEmpty())// 判断是否有数据
            {
                //显示数据
                SimpleAdapter lv_ems = new SimpleAdapter(this,
                        employees,
                        R.layout.employeelist,
                        new String[] { "emid", "emname" },
                        new int[]{R.id.tv_emid,R.id.tv_emname});
                lv_employee.setAdapter(lv_ems);
            }else {
                Toast.makeText(this,"该员工不存在",Toast.LENGTH_SHORT).show();
            }
        }else {
            Toast.makeText(this,"请输入员工编号",Toast.LENGTH_SHORT).show();
        }
    }


//显示数据
    public void showlist(String sql){
        ArrayList> employeelist = employeeDao.Getemployees(sql);
        //ListView适配器
        SimpleAdapter lv_ems = new SimpleAdapter(this,
                employeelist,
                R.layout.employeelist,
                new String[] { "emid", "emname" },
                new int[]{R.id.tv_emid,R.id.tv_emname});
        lv_employee.setAdapter(lv_ems);
    }
}

添加员工，这里先写一下添加按钮的监听方法

case R.id.btn_addem:
                String emid = dt_emid.getText().toString();
                String emname = et_emname.getText().toString();
                String imgurl = url;
                Log.v("add>>>",emid + emname + imgurl);

                if (employeeDao.CheckIsDataAlreadyInDBorNot(emid)) {
                    Toast.makeText(this,
                            "该工号已存在，添加失败", Toast.LENGTH_SHORT).show();
                }else {
                    if((!emid.trim().equals(""))
                            && (!emname.trim().equals(""))
                            && (urlmsg == MsgTable.SUCCESS)){
                        employeeDao.addEmployee(emid,emname,imgurl);
                        Toast.makeText(this,
                                "添加员工成功！", Toast.LENGTH_SHORT).show();
                        Message message = new Message();
                        message.what = MsgTable.REFRESH;
                        handler.sendMessage(message);
                    }else {
                        //switch (v.getId())
                        Toast.makeText(this,
                                "信息不能为空", Toast.LENGTH_SHORT).show();
                    }
                }

         break;