数据库的增删改查

package com.bw.alice.aday14sqlite.db;

1. //封装数据库类名

/**
 * @author alice
 * @version 1.0
 * @Date 2017/8/16 10:38
 */
public class MySQLiteConlums {


    public static final String TABLE_NAME = "Student";
    public static  final String NAME="name";
    public static final String SEX="sex";

}

package com.bw.alice.aday14sqlite.db;


import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;


import com.bw.alice.aday14sqlite.domain.Student;


import java.util.ArrayList;




/**
 * 自己封装的工具类  主要的任务就是用来操作表的
 * @author alice
 * @version 1.0
 * @Date 2017/8/16 10:23
 */
public class MySQLiteUtils {
    private static  MySQLiteUtils mMySQLiteUtils;
    private MySQliteOpenHelper openHelper;//主要用途是获取SQLiteDatabase的对象


    private MySQLiteUtils(Context mContext){
        openHelper = new MySQliteOpenHelper(mContext);//
    }




    public static  synchronized MySQLiteUtils getInstance(Context mContext){
        if(mMySQLiteUtils==null){
            mMySQLiteUtils = new MySQLiteUtils(mContext);
        }
        return mMySQLiteUtils;
    }


    //自己封装一个方法   往student这个表中添加一个学生对象
    public void addStudent(Student student){
        SQLiteDatabase sqLiteDatabase = null;//操作表的
        try {
             sqLiteDatabase = openHelper.getReadableDatabase();//获取SQLiteDatabase的对象
            ContentValues contentValues = new ContentValues();
            contentValues.put(MySQLiteConlums.NAME,student.getName());
            contentValues.put(MySQLiteConlums.SEX,student.getSex());
             sqLiteDatabase.insert(MySQLiteConlums.TABLE_NAME,null,contentValues);//往表中插入一条数据
        }catch (Exception t){


        }finally {
            sqLiteDatabase.close();
        }
//        sqLiteDatabase.execSQL("");
    }






    //封装一个查询表的方法
    public ArrayList<Student> queyStudent(){
        ArrayList<Student> list = new ArrayList<>();
        SQLiteDatabase sqLiteDatabase = null;
        Cursor cursor = null;
        try{
            sqLiteDatabase = openHelper.getReadableDatabase();
            //查询表中的所有数据全部都存入到cursor中
            cursor = sqLiteDatabase.query(MySQLiteConlums.TABLE_NAME, new String[]{MySQLiteConlums.NAME, MySQLiteConlums.SEX}, null, null, null, null, null, null);
//            sqLiteDatabase.execSQL("");
            while (cursor.moveToNext()){
                int nameIndex = cursor.getColumnIndex(MySQLiteConlums.NAME);//列号
                int sexIndex = cursor.getColumnIndex(MySQLiteConlums.SEX);//列
               String name =  cursor.getString(nameIndex);
                String sex = cursor.getString(sexIndex);
                Student student = new Student(name,sex);
                list.add(student);
            }
            return  list;
        }catch (Exception t){


        }finally {
            cursor.close();
            sqLiteDatabase.close();


        }






        return  null;
    }


    //删除一条学生信息
    public  boolean deletStudent(String name){
        SQLiteDatabase sqLiteDatabase = null;
        sqLiteDatabase= openHelper.getReadableDatabase();
        int count = sqLiteDatabase.delete(MySQLiteConlums.TABLE_NAME, MySQLiteConlums.NAME + "='" + name+"'", null);
        if(count!=0){
            return true;
        }
        return false;
    }


    //修改一条学生信息
    public void upDateStudent(String name,Student stu){
        SQLiteDatabase sqlitedatabase = null;
        sqlitedatabase = openHelper.getReadableDatabase();
        ContentValues cv = new ContentValues();
        cv.put(MySQLiteConlums.NAME,stu.getName());
        cv.put(MySQLiteConlums.SEX,stu.getSex());
        int count = sqlitedatabase.update(MySQLiteConlums.TABLE_NAME, cv, MySQLiteConlums.NAME + "='" + name+"'", null);


    }




}

package com.bw.alice.aday14sqlite.db;


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


/**
 * @author alice
 * @version 1.0
 * @Date 2017/8/16 10:13
 */
public class MySQliteOpenHelper extends SQLiteOpenHelper {


    public static final int VEISION = 1;//数据库的版本号，即修改记录
    public static final String SQLITE_NAME = "student.db";//数据库的名称






    /**
     *
     * @param context  上下文对象
     * name   数据库的名称
     * factory   工厂   null
     * version   版本号  数据库的版本号
     */
    public MySQliteOpenHelper(Context context) {
        super(context, SQLITE_NAME, null, VEISION);
    }
    //创建表
    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        //创建Student表   字段  _id自增 ，name ，sex
        sqLiteDatabase.execSQL("create table if not exists Student(_id INTEGER primary key autoincrement,name varchar(20) not null,sex varchar(2))");
    }


    //更新数据库的
    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {


    }
}

package com.bw.alice.aday14sqlite.domain;


/**
 * @author alice
 * @version 1.0
 * @Date 2017/8/16 10:12
 */
public class Student {


    private String name;
    private String sex;
    public Student(String name, String sex) {
        super();
        this.name = name;
        this.sex = sex;
    }
    public Student() {
        super();
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getSex() {
        return sex;
    }
    public void setSex(String sex) {
        this.sex = sex;
    }
    @Override
    public String toString() {
        return "Student [name=" + name + ", sex=" + sex + "]";
    }






}

package com.bw.alice.aday14sqlite;


import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;


import com.bw.alice.aday14sqlite.db.MySQLiteUtils;
import com.bw.alice.aday14sqlite.domain.Student;


import java.util.ArrayList;


public class MainActivity extends AppCompatActivity implements AdapterView.OnItemClickListener, AdapterView.OnItemLongClickListener {
    private EditText et_name,et_sex;
    private Button btn_save,btn_select;
    private ListView listView;
    private ArrayList<String> list;
    private ArrayAdapter<String> mAdapter;
    private MySQLiteUtils mMySQLiteUtils;
    private ArrayList<Student> mStudents;//从表中查询到的所有的数据


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }
    //实例化所有控件
    private void initView() {
        mMySQLiteUtils = MySQLiteUtils.getInstance(this);
        et_name = (EditText) findViewById(R.id.et_name);
        et_sex = (EditText) findViewById(R.id.et_sex);
        btn_save = (Button) findViewById(R.id.btn_save);
        btn_select = (Button) findViewById(R.id.btn_select);
        listView = (ListView) findViewById(R.id.tv_msg);
        list = new ArrayList<>();
        mAdapter = new ArrayAdapter<String>(this,android.R.layout.simple_list_item_1,list);
        listView.setAdapter(mAdapter);
        listView.setOnItemClickListener(this);
        listView.setOnItemLongClickListener(this);


    }


    public void clickBtn(View view) {
        switch (view.getId()){
            case R.id.btn_save://保存数据
                saveStudent();
                break;
            case R.id.btn_select://查询数据
                queyStudent();
                break;


        }






    }
    //查询一张表
    private void queyStudent() {


        mStudents = mMySQLiteUtils.queyStudent();
        list.clear();
        for (int i = 0; i <mStudents.size() ; i++) {
            list.add(mStudents.get(i).toString());
        }
        mAdapter.notifyDataSetChanged();




    }


    private void saveStudent() {
       String name =  et_name.getText().toString();
        String sex = et_sex.getText().toString();
        Student student = new Student(name,sex);
        mMySQLiteUtils.addStudent(student);
    }
    //点击修改数据
    @Override
    public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
        mMySQLiteUtils.upDateStudent(mStudents.get(i).getName(),new Student("晕晕","男"));
        queyStudent();
    }




    @Override
    public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
        mMySQLiteUtils.deletStudent(mStudents.get(i).getName());
        queyStudent();


        return true;
    }
}