Android--数据库相关代码解读

在Android手机操作系统进行实际开发中，进场会应用到数据库。而且在这一平台中对数据库的应用方法比较简单灵活。我们在这里就为大家详细介绍了相关方法，希望可以给大家带来一些帮助。

昨天进行了GUI界面设计，感受了一下android初次设计的愉悦，今天接着学习其SQLite数据库试用，将昨天的例子中数据存到数库中，并读取查看一下。 具体看代码（原写的有点问题，再改写如下）：

1) Android数据库之库操作类：

package com.topsun;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
public class DBHelper {
private static final String TAG = "UserDB_DBHelper.java";
private static final String DataBaseName = "UserDB";
SQLiteDatabase db;
Context context;
public DBHelper(Context context) {
this.open(context);
}
private void createTabel() {
// TODO Auto-generated method stub
String sql = "";
try {
sql = "CREATE TABLE IF NOT EXISTS TestUser (ID INTEGER  PRIMARY KEY autoincrement, NAME TEXT, SEX TEXT, AGES INTEGER)";
this.db.execSQL(sql);
Log.v(TAG, "Create Table TestUser ok");
} catch (Exception e) {
Log.v(TAG, "Create Table TestUser fail");
} finally {
//this.db.close();
Log.v(TAG, "Create Table TestUser ");
}
}
public boolean save(String name, String sex, Integer ages) {
String sql = "insert into TestUser values (null,'" + name + "','" + sex
+ "'," + ages + ")";
try {
this.db.execSQL(sql);
Log.v(TAG, "insert Table TestUser 1 record ok");
return true;
} catch (Exception e) {
Log.v(TAG, "insert Table TestUser 1 record fail");
return false;
} finally {
//this.db.close();
Log.v(TAG, "insert Table TestUser ");
}
}
public Cursor loadAll() {
Cursor cur = db.query("TestUser", new String[]  { "ID", "NAME","SEX","AGES"}, null,
null, null, null, null);
return cur;
}
public void open(Context context){
if (null == db || !this.db.isOpen()){
this.context = context;
this.db = context.openOrCreateDatabase(this.DataBaseName,
context.MODE_PRIVATE, null);
createTabel();
Log.v(this.TAG, "create or Open DataBase。。。");
}
}
public void close() {
db.close();
}
}
package com.topsun;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.util.Log;
public class DBHelper {
private static final String TAG = "UserDB_DBHelper.java";
private static final String DataBaseName = "UserDB";
SQLiteDatabase db;
Context context;
public DBHelper(Context context) {
this.open(context);
}
private void createTabel() {
// TODO Auto-generated method stub
String sql = "";
try {
sql = "CREATE TABLE IF NOT EXISTS TestUser  (ID INTEGER PRIMARY KEY autoincrement,  NAME TEXT, SEX TEXT, AGES INTEGER)";
this.db.execSQL(sql);
Log.v(TAG, "Create Table TestUser ok");
} catch (Exception e) {
Log.v(TAG, "Create Table TestUser fail");
} finally {
//this.db.close();
Log.v(TAG, "Create Table TestUser ");
}
}
public boolean save(String name, String sex, Integer ages) {
String sql = "insert into TestUser values (null,'" + name + "','" + sex
+ "'," + ages + ")";
try {
this.db.execSQL(sql);
Log.v(TAG, "insert Table TestUser 1 record ok");
return true;
} catch (Exception e) {
Log.v(TAG, "insert Table TestUser 1 record fail");
return false;
} finally {
//this.db.close();
Log.v(TAG, "insert Table TestUser ");
}
}
public Cursor loadAll() {
Cursor cur = db.query("TestUser", new String[]  { "ID", "NAME","SEX","AGES"}, null,
null, null, null, null);
return cur;
}
public void open(Context context){
if (null == db || !this.db.isOpen()){
this.context = context;
this.db = context.openOrCreateDatabase(this.DataBaseName,
context.MODE_PRIVATE, null);
createTabel();
Log.v(this.TAG, "create or Open DataBase。。。");
}
}
public void close() {
db.close();
}
}

[/code]

2) Android数据库交互代码

package com.topsun;
import android.app.Activity;
import android.database.Cursor;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
public class guiwindows extends Activity  implements OnClickListener {
EditText TEditname;
EditText TEditsex;
EditText TEditages;
EditText TEditmerge;
Button TSavebutton;
Button TViewbutton;
DBHelper db;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.TEditname = (EditText) this.findViewById (R.id.widgeteditname);
this.TEditsex = (EditText) this.findViewById (R.id.widgeteditsex);
this.TEditages = (EditText) this.findViewById (R.id.widgeteditages);
TEditmerge = (EditText) this.findViewById (R.id.widgeteditmerge);
this.TSavebutton = (Button) this.findViewById (R.id.widgetSavebutton);
TViewbutton = (Button) this.findViewById (R.id.widgetViewbutton);
this.db = new DBHelper(this);
this.TSavebutton.setOnClickListener(this);
this.TViewbutton.setOnClickListener(this);
}
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
// this.TEditages.setText(this.TEditname.getText(). toString()+this.TEditsex.getText().toString());
if (v.getId() == R.id.widgetSavebutton) {
try {
this.db.open(this);
this.db.save(this.TEditname.getText().toString(), this.TEditsex
.getText().toString(), Integer.valueOf(this.TEditages
.getText().toString()));
} catch (Exception e) {
Log.v("save data", "save data fail");
} finally {
this.db.close();
}
} else if (v.getId() == R.id.widgetViewbutton && null != db) {
this.db.open(this);
// 浏览所有数据
Cursor cur = db.loadAll();
StringBuffer sf = new StringBuffer();
cur.moveToFirst();
while (!cur.isAfterLast()) {
sf.append(cur.getInt(0)).append(" : ").append(cur.getString(1))
.append(" : ").append(cur.getString(2)).append(" : ")
.append(cur.getInt(3)).append("\n");
cur.moveToNext();
}
db.close();
this.TEditmerge.setText(sf.toString());
}
}
}

[/code]