2014-10-31Android学习------SQLite数据库操作（四）-----数据库模块（二）增删改查实例展示

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class SQLHelper extends SQLiteOpenHelper {
	
	private final static String DATABASE_NAME = "todo_db";//数据库名
	private final static int DATABASE_VERSION = 1;//数据库版本号
	private final static String TABLE_NAME = "todo_table";//数据库表名
	public final static String FIELD_id = "_id";//
	public final static String FIELD_TEXT = "todo_text";//字段

	public SQLHelper(Context context) {
		super(context, DATABASE_NAME, null, DATABASE_VERSION);
		// TODO Auto-generated constructor stub
	}

	@Override
	public void onCreate(SQLiteDatabase db) {
		// TODO Auto-generated method stub
		String sql = "CREATE TABLE " + TABLE_NAME + " (" + FIELD_id
				+ " INTEGER primary key autoincrement, " + " " + FIELD_TEXT
				+ " text)";
		db.execSQL(sql);

	}

	@Override
	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
		// TODO Auto-generated method stub
		String sql = "DROP TABLE IF EXISTS " + TABLE_NAME;
		db.execSQL(sql);
		onCreate(db);
	}	
	
	
	public Cursor select() {
		SQLiteDatabase db = this.getReadableDatabase();
		Cursor cursor = db
				.query(TABLE_NAME, null, null, null, null, null, null);
		return cursor;
	}

	public long insert(String text) {
		SQLiteDatabase db = this.getWritableDatabase();
		ContentValues cv = new ContentValues();
		cv.put(FIELD_TEXT, text);
		long row = db.insert(TABLE_NAME, null, cv);
		return row;
	}

	public void delete(int id) {
		SQLiteDatabase db = this.getWritableDatabase();
		String where = FIELD_id + " = ?";
		String[] whereValue = { Integer.toString(id) };
		db.delete(TABLE_NAME, where, whereValue);
	}

	public void update(int id, String text) {
		SQLiteDatabase db = this.getWritableDatabase();
		String where = FIELD_id + " = ?";
		String[] whereValue = { Integer.toString(id) };
		ContentValues cv = new ContentValues();
		cv.put(FIELD_TEXT, text);
		db.update(TABLE_NAME, cv, where, whereValue);
	}

}

import com.wust.dbtest.R;

import android.app.Activity;
import android.database.Cursor;
import android.database.sqlite.SQLiteCursor;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.AdapterView;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;


public class DBActivity extends Activity {

	private SQLHelper mySQLHelper;
	private Cursor myCursor;
	private ListView myListView;
	private EditText myEditText;
	private int _id;
	protected final static int MENU_ADD = Menu.FIRST;
	protected final static int MENU_EDIT = Menu.FIRST + 1;
	protected final static int MENU_DELETE = Menu.FIRST + 2;

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		
		// 找到main.xml里面的控件
	    myListView = (ListView) this.findViewById(R.id.myListView);
	    myEditText = (EditText) this.findViewById(R.id.myEditText);
	    //连接数据库
	    mySQLHelper = new SQLHelper(this);
	    //取得数据库里面的内容
	    myCursor = mySQLHelper.select();
	    
	    //为ListView做数据处理
	    SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.list, myCursor, new String[]{ SQLHelper.FIELD_TEXT }, new int[]{ R.id.listTextView1 });
	    myListView.setAdapter(adapter);
	    myListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

			@Override
			public void onItemClick(AdapterView<?> arg0, View view, int position,
					long id) {
				// TODO Auto-generated method stub
		        /* 将myCursor移到所点击的值 */
		        myCursor.moveToPosition(position);
		        /* 取得字段_id的值 */
		        _id = myCursor.getInt(0);
		        /* 取得字段todo_text的值 */
		        myEditText.setText(myCursor.getString(1));
			}
		});
	    
	    myListView.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {

			@Override
			public void onItemSelected(AdapterView<?> arg0, View view,
					int position, long id) {
				// TODO Auto-generated method stub
		        /* getSelectedItem所取得的是SQLiteCursor */
		        SQLiteCursor sc = (SQLiteCursor) arg0.getSelectedItem();
		        _id = sc.getInt(0);
		        myEditText.setText(sc.getString(1));
			}

			@Override
			public void onNothingSelected(AdapterView<?> view) {
				// TODO Auto-generated method stub
				
			}
		});
	}

	//由当前的activity负责执行创建OptionMenu模式的菜单
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// TODO Auto-generated method stub
		super.onCreateOptionsMenu(menu);
	    menu.add(Menu.NONE, MENU_ADD, 0, R.string.strAddButton);
	    menu.add(Menu.NONE, MENU_EDIT, 0, R.string.strEditButton);
	    menu.add(Menu.NONE, MENU_DELETE, 0, R.string.strDeleteButton);

	    return true;
	}

	//菜单被选中的响应事件  参数是选中的那个菜单item
	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// TODO Auto-generated method stub
	    super.onOptionsItemSelected(item);
	    switch (item.getItemId())
	    {
	      case MENU_ADD:
	        this.addTodo();
	        break;
	      case MENU_EDIT:
	        this.editTodo();
	        break;
	      case MENU_DELETE:
	        this.deleteTodo();
	        break;
	    }
	    return true;
	}

	private void deleteTodo() {
		// TODO Auto-generated method stub
		if (_id == 0)
			return;
		/* 删除数据 */
		mySQLHelper.delete(_id);
		myCursor.requery();
		myListView.invalidateViews();// 刷新视图
		myEditText.setText("");
		_id = 0;
	}

	private void editTodo() {
		// TODO Auto-generated method stub
		if (myEditText.getText().toString().equals(""))
			return;
		/* 修改数据 */
		mySQLHelper.update(_id, myEditText.getText().toString());
		myCursor.requery();
		myListView.invalidateViews();// 刷新视图
		myEditText.setText("");
		_id = 0;
	}

	private void addTodo() {
		// TODO Auto-generated method stub
		if (myEditText.getText().toString().equals(""))
			return;
		/* 添加数据到数据库 */
		mySQLHelper.insert(myEditText.getText().toString());
		/* 重新查询 */
		myCursor.requery();
		/* 重新整理myListView */
		myListView.invalidateViews();// 刷新视图
		myEditText.setText("");
		_id = 0;
	}
	
	
	
	

}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/white"
    android:orientation="vertical" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello"
        android:textColor="@drawable/black" />

    <EditText
        android:id="@+id/myEditText"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:textColor="@drawable/black" >
        </EditText>

    <ListView
        android:id="@+id/myListView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/red" >
    </ListView>

</LinearLayout>