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());   
    }   
    }   
    }