sqlite simple demo

crespo09

数据库操作类：
package com.amaker.sqlite;
import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;
/**
* 数据库操作Demo
* @author zzl
*
*/
public class MyDbAdapter {
//创建数据库
public static final String DB_NAME = "per.db";
//创建表
public static final String TABLE_NAME = "pertbl";
//表的一些字段
public static final String ID = "_id";
public static final String NAME = "name";
public static final String AGE = "age";
//数据库版本号
public static final int VERSION = 1;
private Context context;
private SQLiteDatabase db;
private MyDbHelper helper;
//无参构造方法
public MyDbAdapter(){
}
//需要传入上下文的构造方法
public MyDbAdapter(Context context) {
this.context = context;
}
class MyDbHelper extends SQLiteOpenHelper {
public MyDbHelper() {
super(context, DB_NAME, null, VERSION);
}
@Override
public void onCreate(SQLiteDatabase db) {
String sql = "create table PerTbl(_id integer" +
" primary key autoincrement, name text,age integer) ";
db.execSQL(sql);
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("drop table if exists PerTbl");
onCreate(db);
}
}
public MyDbHelper open(){
helper = new MyDbHelper();
db = helper.getWritableDatabase();
return helper;
}
public void close(){
if(helper!=null){
helper.close();
}
}
/**
* 根据sql语句查询
* @param sql
* @return
*/
public Cursor getCursorBysql(String sql){
Log.e("select", "getCursorBysql==========dbs");
return db.rawQuery(sql, null);
}
/**
* 添加
* @param table
* @param contvls
* @return
*/
public long insert(String table,ContentValues contvls){
long row=db.insert(table, null, contvls);
return row;
}
/**
* 更新
* @param id
* @param table
* @param contvls
*/
public int update(String table,ContentValues contvls,String where,String[] whereValue){
int result=db.update(table, contvls, where, whereValue);
return result;
}
/**
* 根据_Id删除
* @param table
*/
public void delete(int id){
String[] args = {String.valueOf(id)};
db.delete(TABLE_NAME, "_id=?", args);
}
}


Activity中的调用：
package com.amaker.sqlite;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import android.app.Activity;
import android.content.ContentValues;
import android.database.Cursor;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements OnClickListener {
private MyDbAdapter dbAdapter;
private Button btn_add;
private Button btn_delete;
private Button btn_update;
private Button btn_find;
private TextView tv;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
dbAdapter = new MyDbAdapter(this);
dbAdapter.open();
}
void init(){
tv = (TextView) findViewById(R.id.tv);
btn_add = (Button) findViewById(R.id.button1);
btn_delete = (Button) findViewById(R.id.button2);
btn_update = (Button) findViewById(R.id.button3);
btn_find = (Button) findViewById(R.id.button4);
btn_add.setOnClickListener(this);
btn_delete.setOnClickListener(this);
btn_update.setOnClickListener(this);
btn_find.setOnClickListener(this);
}
/**
* 添加按钮点击事件
*/
@Override
public void onClick(View v) {
switch (v.getId()) {
//添加按鈕
case R.id.button1:
add();
Toast.makeText(getApplicationContext(), "添加成功！", Toast.LENGTH_LONG).show();
break;
//刪除按鈕
case R.id.button2:
delete();
break;
//修改按鈕
case R.id.button3:
update();
break;
//查找按鈕
case R.id.button4:
query();
break;
default:
break;
}
}
//数据库的添加方法：
public void add(){
ContentValues cv = new ContentValues();
cv.put("name", "zzl");
cv.put("age", 25);
dbAdapter.insert(MyDbAdapter.TABLE_NAME, cv);
}
//数据库更新方法：
public void update(){
try {
ContentValues cv = new ContentValues();
cv.put("name", "li_cai_na");
String[] values ={"1"};
dbAdapter.update(MyDbAdapter.TABLE_NAME, cv, "_id=?", values);
} catch (Exception e) {
e.printStackTrace();
}
}
//数据库查找方法：
public void query(){
List<String> list_name = new ArrayList<String>();
try {
String sql = "select name from pertbl";
Cursor myCursor = dbAdapter.getCursorBysql(sql);
while (myCursor.moveToNext()) {
String str = myCursor.getString(0);
list_name.add(str);
}
myCursor.close();
} catch (Exception e) {
e.printStackTrace();
}
if(list_name.size()>0){
tv.setText(list_name.get(0));
Iterator<String> iterator = list_name.iterator();
while(iterator.hasNext()){
System.out.println(iterator.next()+"、");
}
}
}
//数据库删除方法：
public void delete(){
try {
dbAdapter.delete(3);
} catch (Exception e) {
e.printStackTrace();
}
}
}

未封装，只是简单学习下，因好久没看代码，都忘了，最近因要用到数据库就看下。