增加改查——android数据库篇二

大家好，昨天晚上发布了数据库SQLITE第一篇，今天早上到现在为止，上班也没有什么心思(主要是过年了，大家都是这样子，人嘛总在公司总像一个样子)，所以我从早上到现在一直在写ANDROID，现在是数据库篇二。感觉一个字"累"！

对了，还有一件事，版主和我讲，用JAVA的HIBERNATE反射机制，能不能生成增加改查方法。我还在查看资料。估计能的话，我会在年后写出来。不行我也没办法。起码努力了就行。对吧。,感谢大家。

让我们看一下图，希望大家喜欢！





让我们看这里面所写的部份代码。

下面我们来看一下代码的实现业务方法。

package com.smart;

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteDatabase.CursorFactory;

import android.database.sqlite.SQLiteOpenHelper;

public class SqliteHelper extends SQLiteOpenHelper {

public static final String TB_NAME = "llb";

//构造方法

public SqliteHelper(Context context, String name, CursorFactory factory,

int version) {

super(context, name, null, 1);

}

/**

* 创建新数据库表

*/

@Override

public void onCreate(SQLiteDatabase db) {

db.execSQL("CREATE TABLE IF NOT EXISTS " +

TB_NAME + "(" +

Bean.ID + " integer primary key," +

Bean.CITY + " varchar(10)," +

Bean.CODE + " varcher(20)"+

")");

}

/**

* 当检测与前一次创建数据库版本不一样时，先删除表再创建新表

*/

@Override

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

db.execSQL("DROP TABLE IF EXISTS " + TB_NAME);

onCreate(db);

}

/**

* 变更列名

* @param db

* @param oldColumn

* @param newColumn

* @param typeColumn

*/

public void updateColumn(SQLiteDatabase db, String oldColumn, String newColumn, String typeColumn){

try{

db.execSQL("ALTER TABLE " +

TB_NAME + " CHANGE " +

oldColumn + " "+ newColumn +

" " + typeColumn

);

}catch(Exception e){

e.printStackTrace();

}

}

}

BEAN类

package com.smart;

public class Bean {

public static final String ID = "_id";

public static final String CITY = "city";

public static final String CODE = "code";

private String id;

private String city;

private String code;

public String getId() {

return id;

}

public void setId(String id) {

this.id = id;

}

public String getCity() {

return city;

}

public void setCity(String city) {

this.city = city;

}

public String getCode() {

return code;

}

public void setCode(String code) {

this.code = code;

}

}

Activity类

package com.smart;

import java.util.ArrayList;

import java.util.List;

import android.app.Activity;

import android.content.ContentValues;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

import android.view.View;

import android.view.ViewGroup;

import android.widget.AdapterView;

import android.widget.BaseAdapter;

import android.widget.Button;

import android.widget.EditText;

import android.widget.ListView;

import android.widget.TextView;

/**

* 本例实现SQLite数据库增加、删除、修改、模糊查询操作。这里不是最好的实现方法,

* *

* llb988@126.com

*/

public class Main extends Activity {

private static String DB_NAME = "smart.db";

private static int DB_VERSION = 1;

private static int POSTION;

private ListView listview;

private Cursor cursor;

private SQLiteDatabase db;

private SqliteHelper dbHelper;

private ListAdapter listAdapter;

private EditText etCity;

private EditText etCode;

private Button bt_add;

private Button bt_modify;

private Button bt_query;

private List<Bean> cityList = new ArrayList<Bean>();

/** Called when the activity is first created. */

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

etCity = (EditText) findViewById(R.id.etCity);

etCode = (EditText) findViewById(R.id.etCode);

bt_add = (Button) findViewById(R.id.bt_add);

bt_modify = (Button) findViewById(R.id.bt_modify);

bt_query = (Button) findViewById(R.id.bt_query);

try{

/* 初始化并创建数据库 */

dbHelper = new SqliteHelper(this, DB_NAME, null, DB_VERSION);

/* 创建表 */

db = dbHelper.getWritableDatabase(); //调用SQLiteHelper.OnCreate()

/* 查询表，得到cursor对象 */

cursor = db.query(SqliteHelper.TB_NAME, null, null, null, null, null, Bean.CODE + " DESC");

cursor.moveToFirst();

while(!cursor.isAfterLast() && (cursor.getString(1) != null)){

Bean city = new Bean();

city.setId(cursor.getString(0));

city.setCity(cursor.getString(1));

city.setCode(cursor.getString(2));

cityList.add(city);

cursor.moveToNext();

//得到数据。

}

}catch(IllegalArgumentException e){

//当用SimpleCursorAdapter装载数据时，表ID列必须是_id，否则报错column '_id' does not exist

e.printStackTrace();

//当版本变更时会调用SQLiteHelper.onUpgrade()方法重建表 注：表以前数据将丢失

++ DB_VERSION;

dbHelper.onUpgrade(db, --DB_VERSION, DB_VERSION);

// dbHelper.updateColumn(db, SQLiteHelper.ID, "_"+SQLiteHelper.ID, "integer");

}

listview = (ListView)findViewById(R.id.listView);

listAdapter = new ListAdapter();

listview.setAdapter(listAdapter);

listview.setOnItemClickListener(new ListView.OnItemClickListener(){

@Override

public void onItemClick(AdapterView<?> parent, View view, int postion,

long arg3) {

setSelectedValues(postion);

}

});

/* 插入表数据并ListView显示更新 */

bt_add.setOnClickListener(new Button.OnClickListener(){

@Override

public void onClick(View arg0) {

if(etCity.getText().length() > 1 && etCode.getText().length() >1){

ContentValues values = new ContentValues();

values.put(Bean.CITY, etCity.getText().toString().trim());

values.put(Bean.CODE, etCode.getText().toString().trim());

//插入数据 用ContentValues对象也即HashMap操作,并返回ID号

Long cityID = db.insert(SqliteHelper.TB_NAME, Bean.ID, values);

Bean city = new Bean();

city.setId(""+cityID);

city.setCity(etCity.getText().toString().trim());

city.setCode(etCode.getText().toString().trim());

cityList.add(city);

listview.setAdapter(new ListAdapter());

resetForm();

}

}

});

/* 查询表，模糊条件查询 */

bt_query.setOnClickListener(new Button.OnClickListener(){

@Override

public void onClick(View view) {

cityList.removeAll(cityList);

String sql = null;

String sqlCity = etCity.getText().length() > 0 ? Bean.CITY + " like '%" + etCity.getText().toString().trim() + "%'" : "";

String sqlCode = etCode.getText().length() > 0 ? Bean.CITY + " like '%" + etCity.getText().toString().trim() + "%'" : "";

if( (!"".equals(sqlCity)) && (!"".equals(sqlCode)) ){

sql = sqlCity + " and" + sqlCode;

}else if(!"".equals(sqlCity)){

sql = sqlCity;

}else if(!"".equals(sqlCode)){

sql = sqlCode;

}

cursor = db.query(true, SqliteHelper.TB_NAME,

new String[]{Bean.ID, Bean.CITY, Bean.CODE},

sql,

null, null, null, null, null);

cursor.moveToFirst();

while(!cursor.isAfterLast() && (cursor.getString(1) != null)){

Bean city = new Bean();

city.setId(cursor.getString(0));

city.setCity(cursor.getString(1));

city.setCode(cursor.getString(2));

cityList.add(city);

cursor.moveToNext();

}

listview.setAdapter(new ListAdapter());

resetForm();

}

});

/* 修改表数据 */

bt_modify.setOnClickListener(new Button.OnClickListener(){

@Override

public void onClick(View arg0) {

ContentValues values = new ContentValues();

values.put(Bean.CITY, etCity.getText().toString().trim());

values.put(Bean.CODE, etCode.getText().toString().trim());

db.update(SqliteHelper.TB_NAME, values, Bean.ID + "=" + cityList.get(POSTION).getId(), null);

cityList.get(POSTION).setCity(etCity.getText().toString().trim());

cityList.get(POSTION).setCode(etCode.getText().toString().trim());

listview.setAdapter(new ListAdapter());

resetForm();

}

});

}

/* 设置选中ListView的值 */

public void setSelectedValues(int postion){

POSTION = postion;

etCity.setText(cityList.get(postion).getCity());

etCode.setText(cityList.get(postion).getCode());

}

/* 重值form */

public void resetForm(){

etCity.setText("");

etCode.setText("");

}

@Override

protected void onDestroy() {

db.delete(SqliteHelper.TB_NAME, null, null);

super.onDestroy();

}

private class ListAdapter extends BaseAdapter{

public ListAdapter(){

super();

}

@Override

public int getCount() {

// TODO Auto-generated method stub

return cityList.size();

}

@Override

public Object getItem(int postion) {

// TODO Auto-generated method stub

return postion;

}

@Override

public long getItemId(int postion) {

// TODO Auto-generated method stub

return postion;

}

@Override

public View getView(final int postion, View view, ViewGroup parent) {

view = getLayoutInflater().inflate(R.layout.listview, null);

TextView tv = (TextView) view.findViewById(R.id.tvCity);

tv.setText("" + cityList.get(postion).getCity());

TextView bu = (TextView) view.findViewById(R.id.btRemove);

bu.setText(R.string.delete);

bu.setId(Integer.parseInt(cityList.get(postion).getId()));

/* 删除表数据 */

bu.setOnClickListener(new Button.OnClickListener(){

@Override

public void onClick(View view) {

try{

db.delete(SqliteHelper.TB_NAME, Bean.ID + "=" + view.getId(), null);

cityList.remove(postion);

listview.setAdapter(new ListAdapter());

}catch(Exception e){

e.printStackTrace();

}

}

});

return view;

//返回

}

}

}

本文出自 “技术成就梦想” 博客，请务必保留此出处http://llb988.blog.51cto.com/1940549/486700