SQLite数据库——增删改查

Activity

package com.zdsoft.sqlite1207.activity;

import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;

import com.zdsoft.sqlite1207.adapter.MainListViewAdapter;
import com.zdsoft.sqlite1207.db.DBHelper;
import com.zdsoft.sqlite1207.R;
import com.zdsoft.sqlite1207.entity.Users;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
private EditText et_user, et_password, et_id;
private Button bt_add, bt_delete, bt_select, bt_update;
public DBHelper dbHelper;
private List<Users> list;
private ListView lv_show;
MainListViewAdapter adapter;
SQLiteDatabase sqLiteDatabase;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
initView();
listener();
initData();
sqLiteDatabase.close();

}

private void initView() {
et_user = (EditText) findViewById(R.id.et_user);
et_password = (EditText) findViewById(R.id.et_password);
bt_add = (Button) findViewById(R.id.bt_add);
bt_delete = (Button) findViewById(R.id.bt_delete);
bt_select = (Button) findViewById(R.id.bt_select);

bt_update = (Button) findViewById(R.id.bt_update);
lv_show = (ListView) findViewById(R.id.lv_show);
et_id = (EditText) findViewById(R.id.et_id);
dbHelper = new DBHelper(this);

}

private void listener() {
bt_add.setOnClickListener(this);
bt_delete.setOnClickListener(this);
bt_select.setOnClickListener(this);
bt_update.setOnClickListener(this);

}

private void initData() {
adapter = new MainListViewAdapter(this, getList());
lv_show.setAdapter(adapter);
}

private List<Users> getList() {
// 查询全部
list = new ArrayList<Users>();
sqLiteDatabase = dbHelper.getReadableDatabase();
Cursor cursor = sqLiteDatabase.rawQuery("select * from users", new String[]{});
while (cursor.moveToNext()) {
Users users = new Users();
int id = cursor.getInt(cursor.getColumnIndex("id"));
String username = cursor.getString(cursor.getColumnIndex("username"));
String password = cursor.getString(cursor.getColumnIndex("password"));
users.setId(id);
users.setUsername(username);
users.setPassword(password);
list.add(users);
}

return list;
}

private void refresh() {
list.clear();
list.addAll(getList());
initData();
}

@Override
public void onClick(View v) {

switch (v.getId()) {
case R.id.bt_add:
// 添加
sqLiteDatabase = dbHelper.getWritableDatabase();
sqLiteDatabase.execSQL("insert into users (username,password) values (?,?)", new String[]{et_user.getText().toString(), et_password.getText().toString()});
Toast.makeText(MainActivity.this, "添加成功", Toast.LENGTH_SHORT).show();
et_user.setText("");
et_password.setText("");
refresh();
break;

case R.id.bt_delete:
// 删除
sqLiteDatabase = dbHelper.getWritableDatabase();
sqLiteDatabase.execSQL("delete from users where id > " + et_id.getText().toString() + "");
Toast.makeText(MainActivity.this, "删除成功", Toast.LENGTH_SHORT).show();
et_id.setText("");
refresh();
break;

case R.id.bt_select:
// 查询单个
sqLiteDatabase = dbHelper.getReadableDatabase();
Cursor cursor = sqLiteDatabase.rawQuery("select * from users where id = " + et_id.getText().toString() + "", new String[]{});

if (cursor.moveToFirst()) {
Users users = new Users();
int id = cursor.getInt(cursor.getColumnIndex("id"));
String username = cursor.getString(cursor.getColumnIndex("username"));
String password = cursor.getString(cursor.getColumnIndex("password"));
users.setId(id);
users.setUsername(username);
users.setPassword(password);
Toast.makeText(MainActivity.this, users.getUsername(), Toast.LENGTH_SHORT).show();
}
et_id.setText("");
break;

case R.id.bt_update:
// 修改
sqLiteDatabase = dbHelper.getWritableDatabase();
String str = "update users set username = '" + et_user.getText().toString() + "' , password = '" + et_password.getText().toString() + " ' where id = " + et_id.getText().toString() + "";
sqLiteDatabase.execSQL(str);
Toast.makeText(MainActivity.this, "修改成功", Toast.LENGTH_SHORT).show();
et_id.setText("");
et_user.setText("");
et_password.setText("");
refresh();
break;

default:
break;
}
}
}

Adapter

package com.zdsoft.sqlite1207.adapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

import com.zdsoft.sqlite1207.R;
import com.zdsoft.sqlite1207.entity.Users;

import java.util.ArrayList;
import java.util.List;

/**
* Created by Administrator on 2016/12/7.
*/
public class MainListViewAdapter extends BaseAdapter {
private Context context;
private List<Users> list;

public MainListViewAdapter(Context context, List<Users> list) {
this.context = context;
this.list = list;

}

@Override
public int getCount() {
return list.size();
}

@Override
public Object getItem(int position) {
return null;
}

@Override
public long getItemId(int position) {
return 0;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if (convertView == null) {
viewHolder = new ViewHolder();
convertView = LayoutInflater.from(context).inflate(R.layout.listview_item, null);
viewHolder.tv_id_it = (TextView) convertView.findViewById(R.id.tv_id_it);
viewHolder.tv_user_it = (TextView) convertView.findViewById(R.id.tv_user_it);
viewHolder.tv_password_it = (TextView) convertView.findViewById(R.id.tv_password_it);
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.g
4000
etTag();
}
viewHolder.tv_id_it.setText(String.valueOf(list.get(position).getId()));
viewHolder.tv_user_it.setText(list.get(position).getUsername());
viewHolder.tv_password_it.setText(list.get(position).getPassword());

return convertView;
}

private class ViewHolder {
TextView tv_id_it;
TextView tv_user_it;
TextView tv_password_it;

}
}

App

package com.zdsoft.sqlite1207.app;

import android.app.Application;
import android.database.sqlite.SQLiteDatabase;

import com.zdsoft.sqlite1207.db.DBHelper;

/**
*
* Created by Administrator on 2016/12/7.
*/
public class App extends Application {
public DBHelper dbHelper;

@Override
public void onCreate() {
super.onCreate();
//程序启动，完成数据库的初始化工作。
dbHelper = new DBHelper(this);
SQLiteDatabase sb = dbHelper.getReadableDatabase();
sb.close();
}
}

DB

package com.zdsoft.sqlite1207.db;

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

/**
* Created by Administrator on 2016/12/7.
*/
public class DBHelper extends SQLiteOpenHelper {
/**
* 数据库名称
*/
private final static String DB_NAME = "User.db";

/**
* 写构造方法建库
* @param context
*/

public DBHelper(Context context) {
super(context, DB_NAME, null, 1);
}

/**
* 建表
* @param db
*/
@Override

public void onCreate(SQLiteDatabase db) {
db.execSQL("create table users ( id Integer primary key autoincrement , username varchar (100) , password varchar(100))");

}

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

}
}

实体类

package com.zdsoft.sqlite1207.entity;

/**
* 实体类
* Created by Administrator on 2016/12/7.
*/
public class Users {
private int id;
private String username;
private String password;

public int getId() {
return id;
}

public void setId(int id) {
this.id = id;
}

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}
}

layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<ListView
android:id="@+id/lv_show"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1" />

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
android:layout_width="50dp"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="id:" />

<EditText
android:id="@+id/et_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入id" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
android:layout_width="50dp"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="账号：" />

<EditText
android:id="@+id/et_user"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入用户名"
android:inputType="textPersonName" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
android:layout_width="50dp"
android:layout_height="wrap_content"
android:gravity="center_horizontal"
android:text="密码：" />

<EditText
android:id="@+id/et_password"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:hint="请输入密码"
android:inputType="textPassword" />
</LinearLayout>

<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">

<Button
android:id="@+id/bt_add"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="添加" />

<Button
android:id="@+id/bt_delete"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="删除" />

<Button
android:id="@+id/bt_select"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="查询" />

<Button
android:id="@+id/bt_update"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="修改" />
</LinearLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">

<TextView
android:id="@+id/tv_id_it"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" />

<TextView
android:id="@+id/tv_user_it"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" />

<TextView
android:id="@+id/tv_password_it"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1" />

</LinearLayout>