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
}
}
}

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