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();      }      } 

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());       }       }       }