ANDROID_MARS学习笔记_S01原始版_009_SQLite

一、代码
1.xml
(1)activity_main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     >
 <Button
     android:id="@+id/createDatabase"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="createDatabase"
     />

 <Button
     android:id="@+id/updateDatabase"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="updateDatabase"
     />

 <Button
     android:id="@+id/insert"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="insert"/>
 <Button
     android:id="@+id/update"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="update"/>
 <Button
     android:id="@+id/query"
     android:layout_width="fill_parent"
     android:layout_height="wrap_content"
     android:text="query"/>

 </LinearLayout>

2.java
(1)MainActivity.java

 package com.example.s01_original_e16_sqlite;

 import android.app.Activity;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteOpenHelper;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;

 public class MainActivity extends Activity {

     /** Called when the activity is first created. */
     private Button createButton;
     private Button insertButton;
     private Button updateButton;
     private Button updateRecordButton;
     private Button queryButton;
     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         createButton = (Button)findViewById(R.id.createDatabase);
         updateButton = (Button)findViewById(R.id.updateDatabase);
         insertButton = (Button)findViewById(R.id.insert);
         updateRecordButton = (Button)findViewById(R.id.update);
         queryButton = (Button)findViewById(R.id.query);
         createButton.setOnClickListener(new CreateListener());
         updateButton.setOnClickListener(new UpdateListener());
         insertButton.setOnClickListener(new InsertListener());
         updateRecordButton.setOnClickListener(new UpdateRecordListener());
         queryButton.setOnClickListener(new QueryListener());
     }
     class CreateListener implements OnClickListener{
         @Override
         public void onClick(View v) {
             //创建一个DatabaseHelper对象
             DBHelper dbHelper = new DBHelper(MainActivity.this, "my_sqlite_db");
             //只有调用了DatabaseHelper对象的getReadableDatabase()方法，或者是getWritableDatabase()方法之后，才会创建，或打开一个数据库
             SQLiteDatabase db = dbHelper.getReadableDatabase();
         }
     }
     class UpdateListener implements OnClickListener{

         @Override
         public void onClick(View v) {
             DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
             SQLiteDatabase db = dbHelper.getReadableDatabase();
         }

     }
     class InsertListener implements OnClickListener{

         @Override
         public void onClick(View v) {
             //生成ContentValues对象
             ContentValues values = new ContentValues();
             //想该对象当中插入键值对，其中键是列名，值是希望插入到这一列的值，值必须和数据库当中的数据类型一致
             values.put("id", 1);
             values.put("name","zhangsan");
             DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
             SQLiteDatabase db = dbHelper.getWritableDatabase();
             //调用insert方法，就可以将数据插入到数据库当中
             db.insert("user", null, values);
         }
     }
     //更新操作就相当于执行SQL语句当中的update语句
     //UPDATE table_name SET XXCOL=XXX WHERE XXCOL=XX...
     class UpdateRecordListener implements OnClickListener{

         @Override
         public void onClick(View arg0) {
             // TODO Auto-generated method stub
             //得到一个可写的SQLiteDatabase对象
             DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
             SQLiteDatabase db = dbHelper.getWritableDatabase();
             ContentValues values = new ContentValues();
             values.put("name", "zhangsanfeng");
             //第一个参数是要更新的表名
             //第二个参数是一个ContentValeus对象
             //第三个参数是where子句
             db.update("user", values, "id=?", new String[]{"1"});
         }
     }
     class QueryListener implements OnClickListener{

         @Override
         public void onClick(View v) {
             System.out.println("aaa------------------");
             Log.d("myDebug", "myFirstDebugMsg");

             DBHelper dbHelper = new DBHelper(MainActivity.this,"my_sqlite_db",2);
             SQLiteDatabase db = dbHelper.getReadableDatabase();
             Cursor cursor = db.query("user", new String[]{"id","name"}, "id=?", new String[]{"1"}, null, null, null);
             while(cursor.moveToNext()){
                 String name = cursor.getString(cursor.getColumnIndex("name"));
                 System.out.println("query--->" + name);
             }
         }
     }

 }

(2)DBHelper.java

 package com.example.s01_original_e16_sqlite;

 import android.content.Context;
 import android.database.sqlite.SQLiteDatabase;
 import android.database.sqlite.SQLiteDatabase.CursorFactory;
 import android.database.sqlite.SQLiteOpenHelper;

 public class DBHelper extends SQLiteOpenHelper {

     private static final int VERSION = 1;
     //在SQLiteOepnHelper的子类当中，必须有该构造函数
     public DBHelper(Context context, String name, CursorFactory factory,
             int version) {
         //必须通过super调用父类当中的构造函数
         super(context, name, factory, version);
         // TODO Auto-generated constructor stub
     }
     public DBHelper(Context context,String name){
         this(context,name,VERSION);
     }
     public DBHelper(Context context,String name,int version){
         this(context, name,null,version);
     }

     //该函数是在第一次创建数据库的时候执行,实际上是在第一次得到SQLiteDatabse对象的时候，才会调用这个方法
     @Override
     public void onCreate(SQLiteDatabase db) {
         // TODO Auto-generated method stub
         System.out.println("create a Database");
         //execSQL函数用于执行SQL语句
         db.execSQL("create table user(id int,name varchar(20))");
     }

     @Override
     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
         // TODO Auto-generated method stub
         System.out.println("update a Database");
     }

 }