结合listview实现sqlite3数据库的增删改查

1.首先看一下界面效果和功能

点了Menu键后弹出增加和查询按钮

选中增加并增加一些内容，点确认即可显示到listview上

长按选中item会弹出删除和修改选项，删除就会删掉选中的item

点了编辑就会显示后会得到item的值，并可以修改它

2.实现思路

• 在oncreate方法中调用SQLiteOpenHelper创建数据库
• 创建一个数据库操作类，里面有曾删改等方法
• 在主界面调用增删改方法对界面上的数据进行操作

3.具体实现

数据库操作类的代码

package android.jim.com.dbstorage;

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

/**
 * Created by huangjim on 7/22/2015.
 */
public class DBStorageDemo {
    private Context mContext;
    private SQLiteDatabase mSQLiteDatabase;
    //public final String DATABASE_NAME="userInfo";
    public final static String TABLE_NAME="users2";
    public final static String USER_NAME="userName";
    public final static String USER_ADDRESS = "userAddress";


    public DBStorageDemo(Context _Context){
        this.mContext=_Context;
    }

    //创建和打开数据库
    public void openOrCreateDatabase(){

        MyDatabaseOpenHelper openHelper=new MyDatabaseOpenHelper(mContext,TABLE_NAME,null,1);
        mSQLiteDatabase=openHelper.getReadableDatabase();
    }

    //关闭数据库
    public void closeUser(){
        mSQLiteDatabase.close();
        //mSQLiteDatabase=null;
    }

    //添加用户
    public long insertUser(Users users){

        if (mSQLiteDatabase!=null&&users!=null) {

            ContentValues _ContentValues = new ContentValues();
            _ContentValues.put(USER_NAME, users.getUserName());
            _ContentValues.put(USER_ADDRESS, users.getUserAddress());

            return mSQLiteDatabase.insert(TABLE_NAME, "", _ContentValues);
        }
       /* mSQLiteDatabase.execSQL("insert into TABLE_NAME values(null,?.?)",
                new String[]{users.getUserName(),users.getUserAddress()});*/
        return -1;
    }

    //返回整个表的游标
    public Cursor selectAll(){
        //return mSQLiteDatabase.rawQuery("select * from TABLE_NAME",null);
        if (mSQLiteDatabase!=null) {
            return mSQLiteDatabase.query(TABLE_NAME, new String[]{"_id",USER_NAME, USER_ADDRESS}, null,
                    null, null, null, null);
        }else {
            return null;
        }
    }

    //查询用户用
    public Cursor selectUser( String selection, String[] selectionArgs, String groupBy, String having, String orderBy){
        if (mSQLiteDatabase!=null) {
            return mSQLiteDatabase.query(TABLE_NAME, new String[]{USER_NAME, USER_ADDRESS}, selection,
                    selectionArgs, groupBy, having, orderBy);
        }else {
            return null;
        }
    }

    //删除用户
    public void deleteUser(int itemId){

        if (mSQLiteDatabase!=null) {
            mSQLiteDatabase.execSQL("delete from "+ TABLE_NAME +" where _id= "+ Integer.toString(itemId));
            //closeUser();
           //mSQLiteDatabase.delete(TABLE_NAME, "_id =?", new String[]{String.valueOf(itemId)});
        }
    }

    //更新用户信息
    public void updateUser(int itemId,Users users){
        if (mSQLiteDatabase!=null){
            //mSQLiteDatabase.execSQL("update "+TABLE_NAME+" set userName= "+users.getUserName()+" set userAddress= "+users.getUserAddress()+" where _id= "+ Integer.toString(itemId));
            ContentValues contentValues=new ContentValues();
            contentValues.put(USER_NAME,users.getUserName());
            contentValues.put(USER_ADDRESS,users.getUserAddress());
            mSQLiteDatabase.update(TABLE_NAME,contentValues,"_id=?",new String[]{Integer.toString(itemId)});
        }
    }
}

其中在openOrCreateDatabase中调用了SQLiteOpenHelper类来初始化数据库，这个类的实现非常简单

package android.jim.com.dbstorage;

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

/**
 * Created by huangjim on 7/22/2015.
 */
public class MyDatabaseOpenHelper extends SQLiteOpenHelper {
    public MyDatabaseOpenHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {

        db.execSQL("create table " + DBStorageDemo.TABLE_NAME
                + "(_id integer primary key autoincrement,"
                + DBStorageDemo.USER_NAME + " varchar(50),"
                + DBStorageDemo.USER_ADDRESS + " varchar(250))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

    }
}

这里直接继承了ListActivity，其中长按删除和编辑用到的方法是根据当前item的id找到对应数据在数据库里的_id，然后删除数据库里的内容，再把数据库的内容显示出来。

package android.jim.com.dbstorage;

import android.app.AlertDialog;
import android.app.Dialog;
import android.app.ListActivity;
import android.content.DialogInterface;
import android.database.Cursor;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
import android.widget.TextView;
import android.widget.Toast;


public class MainActivity extends ListActivity {

    private DBStorageDemo dbStorageDemo;
    //private Users users;
    private final int USERDIALOG_ID = 2345;
    private final int ITEM_MODIFY = 1;
    private final int ITEM_DELETE = 2;
    private final int ITEM_ADD = 3;
    private final int ITEM_QUERY = 4;
    private int listPosition;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        dbStorageDemo = new DBStorageDemo(this);
        dbStorageDemo.openOrCreateDatabase();
        //启动时显示的内容
        displayList();

        //注册上下文菜单
        registerForContextMenu(getListView());
    }

    private void displayList() {
        Cursor cursor = dbStorageDemo.selectAll();
        if (cursor != null) {
            SimpleCursorAdapter adapter = new SimpleCursorAdapter(MainActivity.this, android.R.layout.simple_expandable_list_item_2
                    , cursor, new String[]{dbStorageDemo.USER_NAME, dbStorageDemo.USER_ADDRESS}, new int[]{android.R.id.text1, android.R.id.text2});
            setListAdapter(adapter);
        }
    }

    //创建菜单
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add(1, ITEM_ADD, 1, "增加");
        menu.add(2, ITEM_QUERY, 2, "查询");
        //getMenuInflater().inflate(R.menu.menu_main,menu);

        //return super.onCreateOptionsMenu(menu);
        return true;
    }

    //选中菜单事件
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        if (item.getItemId() == ITEM_ADD) {

            //显示一个dialog
            showDialog(USERDIALOG_ID);
        }
        //return super.onOptionsItemSelected(item);
        return true;
    }

    //创建一个dialog
    @Override
    protected Dialog onCreateDialog(int id) {
        if (id == USERDIALOG_ID) {
            AlertDialog dialog = new AlertDialog.Builder(MainActivity.this)
                    .setTitle("添加用户")
                    .setIcon(R.drawable.ic_launcher)
                    .setView(LayoutInflater.from(MainActivity.this).inflate(R.layout.activity_dialog, null))
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            AlertDialog alertDialog = (AlertDialog) dialog;
                            EditText editName = (EditText) alertDialog.findViewById(R.id.et_userName);
                            EditText editAddress = (EditText) alertDialog.findViewById(R.id.et_userAddress);
                            Users users = new Users();
                            users.setUserName(editName.getText().toString());
                            users.setUserAddress(editAddress.getText().toString());
                            dbStorageDemo.insertUser(users);
                            dialog.dismiss();
                            displayList();
                            editName.setText("");
                            editAddress.setText("");

                        }
                    })
                    .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                            showToast("你点了取消！");

                        }
                    })
                    .show();

            return dialog;
        }
        return null;
    }

    private void showToast(String msg) {

        Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
    }

    @Override
    protected Dialog onCreateDialog(int id, Bundle args) {
        if (id == 123) {
            View view = LayoutInflater.from(MainActivity.this).inflate(R.layout.activity_dialog, null);
            EditText editName = (EditText) view.findViewById(R.id.et_userName);
            EditText editAddress = (EditText) view.findViewById(R.id.et_userAddress);
            editName.setText(args.getString("name", "null"));
            editAddress.setText(args.getString("address", "null"));
            AlertDialog dialog = new AlertDialog.Builder(MainActivity.this)
                    .setTitle("修改内容")
                    .setIcon(R.drawable.ic_launcher)
                    .setView(view)
                    .setPositiveButton("确定", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {

                            AlertDialog alertDialog = (AlertDialog) dialog;
                            EditText editName = (EditText) alertDialog.findViewById(R.id.et_userName);
                            EditText editAddress = (EditText) alertDialog.findViewById(R.id.et_userAddress);
                            Users users = new Users();
                            users.setUserName(editName.getText().toString());
                            users.setUserAddress(editAddress.getText().toString());
                            int itemId = getDatabaseID(listPosition);
                            dbStorageDemo.updateUser(itemId, users);
                            dialog.dismiss();
                            displayList();

                        }
                    })
                    .setNegativeButton("取消", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int which) {
                            dialog.dismiss();
                            showToast("你点了取消！");
                        }
                    }).show();
        }

        return super.onCreateDialog(id, args);
    }

    //创建上下文菜单并指定itemId
    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenu.ContextMenuInfo menuInfo) {
        super.onCreateContextMenu(menu, v, menuInfo);
        menu.add(1, ITEM_MODIFY, 1, "编辑");
        menu.add(1, ITEM_DELETE, 2, "删除");
    }

    //长按菜单响应函数 并获取选中的listview行内容
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        ContextMenu.ContextMenuInfo info = item.getMenuInfo();
        AdapterView.AdapterContextMenuInfo contextMenuInfo = (AdapterView.AdapterContextMenuInfo) info;

        //选中行位置
        listPosition = contextMenuInfo.position;
        //响应事件
        switch (item.getItemId()) {
            //得到_id删除选中的item
            case ITEM_DELETE:
                dbStorageDemo.deleteUser(getDatabaseID(listPosition));
                //showToast(listPosition + "");
                displayList();
                break;
            //调用dialog，并在dialog中加入当前item的数据，修改item的内容
            case ITEM_MODIFY:
                ListView listView = getListView();
                View view = listView.getChildAt(listPosition);
                String name = ((TextView) view.findViewById(android.R.id.text1)).getText().toString();
                String address = ((TextView) view.findViewById(android.R.id.text2)).getText().toString();
                Bundle bundle = new Bundle();
                bundle.putString("name", name);
                bundle.putString("address", address);
                showDialog(123, bundle);
                break;
        }
        return super.onContextItemSelected(item);
    }

    //根据listview中item的id找到对应的数据库中的_id并返回
    private int getDatabaseID(int position) {

        ListView listView = getListView();
        View view = listView.getChildAt(position);

        //得到选中item的数据
        String name = ((TextView) view.findViewById(android.R.id.text1)).getText().toString();
        String address = ((TextView) view.findViewById(android.R.id.text2)).getText().toString();

        showToast(name);
        Cursor cursor = dbStorageDemo.selectAll();

        //遍历数据库找到跟item内容相同的信息
        while (cursor.moveToNext()) {

            //得到数据库的数据
            String deleteName = cursor.getString(cursor.getColumnIndex(dbStorageDemo.USER_NAME));
            String deleteAddress = cursor.getString(cursor.getColumnIndex(dbStorageDemo.USER_ADDRESS));
            if (name.equals(deleteName) && address.equals(deleteAddress)) {
                //返回第一列即_id
                return cursor.getInt(0);
            }
        }
        return -1;
    }
}

其中在增加用户的时候用了一个User类来传递内容

package android.jim.com.dbstorage;

/**
 * Created by huangjim on 7/22/2015.
 */
public class Users {

    private String userName;
    private String userAddress;

    public String getUserAddress() {
        return userAddress;
    }

    public void setUserAddress(String userAddress) {
        this.userAddress = userAddress;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }
}

在数据库操作类里已经把查询的方法写进去了，太耗时间就没写了。水平有限，如有不正确的地方请多多指出。