android自学之sqlitedatabase小例子

 功能实现单词本的添加与查询单词

查询结果图如下

 

代码如下：

查询结果使用的activity是dialog风格的activity，在manifest文件中如此配置

 

<activity android:name=".ResultActivity"
           android:label="查询结果"
           android:theme="@android:style/Theme.Dialog"></activity>

要实现数据库的增删改查，需要三步：

1.继承SQLiteOpenHelper复写onCreate方法，一般在里面实现创建表的工作。

2.通过SQLiteOpenHelper的getReadableDatabase或者getWriteableDatabase方法创建数据库

3.调用数据库增删改查方法进行数据操作

 

java代码如下

 

package com.example.mysqliitedatabase;

import android.provider.BaseColumns;
import android.provider.SyncStateContract.Columns;
//定义数据库表的名字及表的列名
public class Words {
    static class MyColumn implements BaseColumns{
        final static String TABLE_NAME="dict";
        final static String _ID="_id";
        final static String WORD="word";
        final static String DETAIL="detail";
    }
}

 

package com.example.mysqliitedatabase;

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

public class MySqliteDatabaseHelper extends SQLiteOpenHelper {

    String CreateTable="create table dict"+"("+Words.MyColumn._ID+"integer primary key ,"+Words.MyColumn.WORD+","+Words.MyColumn.DETAIL+")";

    public MySqliteDatabaseHelper(Context context, String name,
            CursorFactory factory, int version) {
        super(context, name, factory, version);
        // TODO Auto-generated constructor stub
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub
        db.execSQL(CreateTable);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub

    }

}

 

package com.example.mysqliitedatabase;


import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;
import java.util.Stack;

import android.os.Bundle;
import android.app.Activity;
import android.content.ContentValues;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.text.TextUtils;
//import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity {

    private EditText wordString;
    private EditText detailString;
    private EditText queryString;
    private SQLiteDatabase database;
    private Button addButton;
    private Button queryButton;
    String[] returnColums={Words.MyColumn.WORD,Words.MyColumn.DETAIL};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        final MySqliteDatabaseHelper datanaseHelper=new MySqliteDatabaseHelper(getApplicationContext(), "dict.db",null,1);
        wordString=(EditText) findViewById(R.id.editText1);
        detailString=(EditText) findViewById(R.id.editText2);
        queryString=(EditText) findViewById(R.id.editText3);
        addButton= (Button) findViewById(R.id.button1);
        queryButton=(Button) findViewById(R.id.button2);

        addButton.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                final String word=wordString.getText().toString();
                final String detail=detailString.getText().toString();

                database=datanaseHelper.getWritableDatabase();

                ContentValues contentValues=new ContentValues();
                contentValues.put(Words.MyColumn.WORD,word);
                contentValues.put(Words.MyColumn.DETAIL,detail);

                database.insert("dict", null,contentValues);

                Toast.makeText(getApplicationContext(), "add success",1000).show();
            }
        });

        queryButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                database=datanaseHelper.getWritableDatabase();
                String query=queryString.getText().toString();
                String[] selectionArgs = null;
                String selection = null;
                Cursor cursor;
                if (!TextUtils.isEmpty(query)) {
                    selectionArgs=new String[]{query};
                    selection=Words.MyColumn.WORD+"= ?";
                }

                cursor=database.query("dict", returnColums, selection, selectionArgs, null,null,null);
                ArrayList<Map<String,String>> list=new ArrayList<Map<String,String>>();
                if (cursor!=null) {
                    while (cursor.moveToNext()) {
                        Map<String,String> map=new HashMap<String, String>();
                        int wordIndex=cursor.getColumnIndex(Words.MyColumn.WORD);
                        int detailIndex=cursor.getColumnIndex(Words.MyColumn.DETAIL);
                        map.put(Words.MyColumn.WORD,cursor.getString(wordIndex));
                        map.put(Words.MyColumn.DETAIL,cursor.getString(detailIndex));
                        list.add(map);
                    }
                    Toast.makeText(getApplicationContext(), "query success",1000).show();
                    Intent intent=new Intent(getApplicationContext(), ResultActivity.class);
                    Bundle bundle=new Bundle();
                    bundle.putSerializable("data",list);
                    intent.putExtras(bundle);
                    startActivity(intent);
                }
                else {
                    Toast.makeText(getApplicationContext(), "cursor is null",1000).show();
                }
            }
        });
    }
}

 

package com.example.mysqliitedatabase;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.ListView;
import android.widget.SimpleAdapter;

public class ResultActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    ListView listView=new ListView(getApplicationContext());
    setContentView(listView);

    Intent intent=getIntent();
    ArrayList<Map<String,String>> list=(ArrayList<Map<String, String>>) intent.getSerializableExtra("data");
    SimpleAdapter adapter=new SimpleAdapter(getApplicationContext(), list, R.layout.main, new String[]{Words.MyColumn.WORD,Words.MyColumn.DETAIL},new int[]{R.id.text1,R.id.text2});
    listView.setAdapter(adapter);
}
}