Android复习(十五)
SQLiteSQLiteActivity
package org.wp.activity;import org.wp.db.DatabaseHelper;import android.app.Activity;import android.content.ContentValues;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.os.Bundle;import android.util.Log;import android.view.View;import android.widget.Button;/** * adb访问SQLite * cmd --> adb * adb shell ** ls -l --> cd data --> ls -l --> cd data --> ls -l --> cd org.wp.activity --> ls * cd --> databases * SQLite sqlite_db * .schema * select * from user; ** @author wp **/public class SQLiteActivity extends Activity {private static final String TAG = "SQLiteActivity";private Button createDBButton;private Button updateDBButton;private Button insertButton;private Button updateButton;private Button deleteButton;private Button queryButton;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);createDBButton = (Button) findViewById(R.id.createDatabase);updateDBButton = (Button) findViewById(R.id.updateDatabase);insertButton = (Button) findViewById(R.id.insert);updateButton = (Button) findViewById(R.id.update);deleteButton = (Button) findViewById(R.id.delete);queryButton = (Button) findViewById(R.id.query);createDBButton.setOnClickListener(listener);updateDBButton.setOnClickListener(listener);insertButton.setOnClickListener(listener);updateButton.setOnClickListener(listener);deleteButton.setOnClickListener(listener);queryButton.setOnClickListener(listener);}private View.OnClickListener listener = new View.OnClickListener() {@Overridepublic void onClick(View arg0) {Button button = (Button) arg0;switch (button.getId()) {case (R.id.createDatabase):// 创建一个DatabaseHelper对象DatabaseHelper dbHelper1 = new DatabaseHelper(SQLiteActivity.this, "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 db1 = dbHelper1.getReadableDatabase();break;case (R.id.updateDatabase):DatabaseHelper dbHelper2 = new DatabaseHelper(SQLiteActivity.this, "sqlite_db", 2);SQLiteDatabase db2 = dbHelper2.getReadableDatabase();break;case (R.id.insert):DatabaseHelper dbHelper3 = new DatabaseHelper(SQLiteActivity.this, "sqlite_db");SQLiteDatabase db3 = dbHelper3.getWritableDatabase();// 生成ContentValues对象ContentValues values1 = new ContentValues();// 向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values1.put("id", 1);values1.put("name", "某某某1");values1.put("age", 25);// 调用insert方法，就可以将数据插入到数据库当中db3.insert("user", null, values1);values1.put("id", 2);values1.put("name", "某某某2");values1.put("age", 10);// 调用insert方法，就可以将数据插入到数据库当中db3.insert("user", null, values1);break;case (R.id.delete):DatabaseHelper dbHelper4 = new DatabaseHelper(SQLiteActivity.this, "sqlite_db");SQLiteDatabase db4 = dbHelper4.getWritableDatabase();db4.delete("user", "id = ?", new String[] { "1" });break;case (R.id.update):DatabaseHelper dbHelper5 = new DatabaseHelper(SQLiteActivity.this, "sqlite_db");SQLiteDatabase db5 = dbHelper5.getWritableDatabase();ContentValues values2 = new ContentValues();values2.put("name", "张三1");values2.put("age", 33);db5.update("user", values2, "id = ?", new String[] { "1" });values2.put("name", "张三2");values2.put("age", 15);db5.update("user", values2, "id = ?", new String[] { "2" });break;case (R.id.query):DatabaseHelper dbHelper6 = new DatabaseHelper(SQLiteActivity.this, "sqlite_db");SQLiteDatabase db6 = dbHelper6.getReadableDatabase();Cursor cursor = db6.query("user", new String[] { "id", "name","age" }, "id = ?", new String[] { "1" }, null, null,null);while (cursor.moveToNext()) {int id = cursor.getInt(cursor.getColumnIndex("id"));String name = cursor.getString(cursor.getColumnIndex("name"));int age = cursor.getInt(cursor.getColumnIndex("age"));Log.i(TAG, "count:" + cursor.getCount());Log.i(TAG, "columnCount:" + cursor.getColumnCount());Log.i(TAG, "id:" + id + ",name:" + name + ",age:" + age);}break;}}};}
DatabaseHelper
package org.wp.db;import android.content.Context;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.database.sqlite.SQLiteDatabase.CursorFactory;import android.util.Log;/** * DatabaseHelper作为一个访问SQLite的助手类，提供两个方面的功能* 第一: getReadableDatabase(),getWritableDatabase() * 可以获得SQLiteDatabse对象，通过该对象可以对数据库进行操作 * 第二: 提供了onCreate()和onUpgrade()两个回调函数 * 允许我们在创建和升级数据库时，进行自己的操作 ** @author wp **/public class DatabaseHelper extends SQLiteOpenHelper {private static final String TAG = "DatabaseHelper";private static final int VERSION = 1;public DatabaseHelper(Context context, String name) {this(context, name, VERSION);}public DatabaseHelper(Context context, String name, int version) {this(context, name, null, version);}// 在SQLiteOpenHelper的子类当中，必须有该构造函数public DatabaseHelper(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);}// 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@Overridepublic void onCreate(SQLiteDatabase db) {Log.i(TAG, "Create Database");db.execSQL("create table user(id int,name varchar(20),age int)");}@Overridepublic void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {Log.i(TAG, "Update Database");}}
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" ><Buttonandroid:id="@+id/createDatabase"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="createDatabase"/><Buttonandroid:id="@+id/updateDatabase"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="updateDatabase"/><Buttonandroid:id="@+id/insert"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="insert"/><Buttonandroid:id="@+id/update"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="update"/><Buttonandroid:id="@+id/delete"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="delete"/><Buttonandroid:id="@+id/query"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="query"/></LinearLayout>
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