Android实验6：数据存储和访问

  分别使用sqlite3工具和Android代码的方式建立SQLite数据库。在数据库建立完成后，编程实现基本的数据库添加和删除功能。创建一个学生管理的APP，基本信息包含学生姓名，班级，学号。采用数据库存储这些信息。应用应该至少包含信息录入和删除功能。数据显示考虑采用ListView。

MainActivity.java

import android.app.Activity;
import android.os.Bundle;
import android.view.MenuItem;
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 android.widget.PopupMenu;
import java.util.ArrayList;
import java.util.List;

public  class MainActivity extends Activity {

    private DBAdapter dbAdapter;

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

        final Button btnAdd = (Button) findViewById(R.id.btnAdd);
        final ListView lv1 = (ListView) findViewById(R.id.lv1);
        final EditText addClassEditText = (EditText) findViewById(R.id.addClass);
        final EditText addSnoEditText = (EditText) findViewById(R.id.addSno);
        final EditText addSnameEditText = (EditText) findViewById(R.id.addSname);

        dbAdapter = new DBAdapter(this);
        dbAdapter.open();

        List list = new ArrayList();
        list.add("ID" + "         " + "班级" + "           " + "学号" + "            " + "姓名");
        ArrayAdapter adapter = new ArrayAdapter(this, android.R.layout.simple_list_item_1, list);
        lv1.setAdapter(adapter);

        btnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Student ss = new Student();
                String sno = addSnoEditText.getText().toString();
                String sname = addSnameEditText.getText().toString();
                String classes = addClassEditText.getText().toString();
                ArrayAdapter temp_adp = (ArrayAdapter) lv1.getAdapter();
                temp_adp.add(dbAdapter.insert(ss) + "  " + classes + "  " + sno + "   " + sname);
            }
        });

        lv1.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
            @Override
            public boolean onItemLongClick(AdapterView parent, View view, final int position, long id) {
                if (id > 0) {
                    PopupMenu popup = new PopupMenu(MainActivity.this, view);
                    popup.getMenuInflater().inflate(R.menu.main, popup.getMenu());
                    popup.show();
                    popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                        @Override
                        public boolean onMenuItemClick(MenuItem item) {
                            switch (item.getItemId()) {
                                case R.id.menu1:
                                    ArrayAdapter temp_adp = (ArrayAdapter) lv1.getAdapter();
                                    temp_adp.remove(temp_adp.getItem(position));
                                    return true;
                                default:
                                    return false;
                            }
                        }
                    });
                }
                return true;
            }
        });

    }
}

DBAdapter.java

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteOpenHelper;

public class DBAdapter {

    private final Context context;
    private SQLiteDatabase db;
    private DBHelper dbHelper;
    private final static String DB_TABLE="studentinfo";
    private final static String DB_NAME="student.db";
    private final static int DB_VERSION=1;
    private final static String KEY_ID="id";
    private final static String KEY_SNO="sno";
    private final static String KEY_SNAME="sname";
    private final static String KEY_CLASSES="classes";

    public DBAdapter(Context _cContext) {
        context = _cContext;
    }

    public void close()
    {
        if(db!=null)
        {
            db.close();
            db=null;
        }
    }

    public void open() throws SQLiteException
    {
        dbHelper = new DBHelper(context, DB_NAME, null, DB_VERSION);
        try
        {
            db = dbHelper.getWritableDatabase();
        }
        catch(Exception e)
        {
            db  = dbHelper.getReadableDatabase();
        }
    }

    public long insert(Student s)
    {

        ContentValues cv = new ContentValues();
        cv.put(KEY_SNO,s.getSno() );
        cv.put(KEY_SNAME, s.getSname());
        cv.put(KEY_CLASSES, s.getClasses());
        return db.insert(DB_TABLE, null, cv);
    }


    public Student[] convertToStudent(Cursor c)
    {
        int resultsCount = c.getCount();
        if(resultsCount==0||!c.moveToFirst())
        {
            return null;
        }

        Student []stu = new Student[resultsCount];
        for (int i = 0; i < stu.length; i++) {

            stu[i] = new Student();
            String sno  = c.getString(c.getColumnIndex("sno"));
            String sname = c.getString(c.getColumnIndex("sname"));
            String classes = c.getString(c.getColumnIndex("classes"));
            stu[i].id=c.getInt(0);
            stu[i].setSno(sno);
            stu[i].setSname(sname);
            stu[i].setClasses(classes);
            c.moveToNext();
        }
        return stu;
    }

    private   static class DBHelper extends SQLiteOpenHelper{

        public DBHelper(Context context, String name, CursorFactory factory, int version) {
            super(context, name, factory, version);
        }
        private static final String SQL="CREATE TABLE studentinfo ("
                + "id INTEGER PRIMARY KEY AUTOINCREMENT,"
                + "sno TEXT DEFAULT NONE,"
                + "sname TEXT DEFAULT NONE,"
                + "classes TEXT DEFAULT NONE"
                + ")";

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL(SQL);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS"+DB_TABLE);
            onCreate(db);

        }
    }
}

Student.java

import java.io.Serializable;

public class Student implements Serializable{

    public  int id=-1;
    public String sno;
    public  String sname;
    public String classes;

    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getSno() {
        return sno;
    }
    public void setSno(String sno) {
        this.sno = sno;
    }
    public String getSname() {
        return sname;
    }
    public void setSname(String sname) {
        this.sname = sname;
    }
    public String getClasses() {
        return classes;
    }
    public void setClasses(String classes) {
        this.classes = classes;
    }
    @Override
    public String toString() {
        return "id：" + id +"  " + "学号：" + sno +"  "+ "姓名：" + sname +"  "+ "班级：" + classes ;
    }
}

activity_main.xml