SQLite小例子

来源：互联网发布：苹果下载不了淘宝编辑：程序博客网时间：2024/06/05 17:37

这是我在网站看到过一个网友做的SQLite一个小程序，觉得写的不错，以供提示参考，所以把转载下来了。其实就是一个小收藏夹。

代码如下：

ActivityMain_1.java

view plaincopy to clipboardprint?
01.public class ActivityMain_1 extends Activity {
02.    //声明EditText实例
03.    private EditText et1,et2,et3;
04.    //声明Button实例
05.    private Button button;
06.
07.    @Override
08.    protected void onCreate(Bundle savedInstanceState) {
09.        // TODO Auto-generated method stub
10.        super.onCreate(savedInstanceState);
11.        setContentView(R.layout.main_1);
12.
13.        //根据ID获得实例对象
14.        et1 = (EditText) findViewById(R.id.EditText01);
15.        et2 = (EditText) findViewById(R.id.EditText02);
16.        et3 = (EditText) findViewById(R.id.EditText03);
17.        button = (Button) findViewById(R.id.button);
18.
19.        //事件
20.        button.setOnClickListener(new View.OnClickListener() {
21.
22.            @Override
23.            public void onClick(View v) {
24.                String name=et1.getText().toString();
25.                String url =et2.getText().toString();
26.                String desc = et3.getText().toString();
27.
28.                ContentValues values = new ContentValues();
29.
30.                values.put("name", name);
31.                values.put("url", url);
32.                values.put("desc", desc);
33.
34.                //实例化数据库帮助类
35.                DBHelper helper = new DBHelper(getApplicationContext());
36.                //打开数据库
37.                helper.open();
38.
39.                //插入数据
40.                helper.insert(values);
41.                //实例化Intent
42.                Intent intent = new Intent(ActivityMain_1.this,QueryActivity.class);
43.                startActivity(intent);
44.                helper.close();
45.            }
46.        });
47.
48.    }
49.
50.
51.}

QueryActivity.java

view plaincopy to clipboardprint?
01.public class QueryActivity extends ListActivity {
02.
03.    private ListView listView;
04.    private Cursor c;
05.
06.    @Override
07.    protected void onCreate(Bundle savedInstanceState) {
08.        // TODO Auto-generated method stub
09.        super.onCreate(savedInstanceState);
10.        //setContentView(R.layout.row);
11.
12.        //实例化数据库帮助类
13.        final DBHelper help = new DBHelper(this);
14.        help.open();
15.        c= help.query();
16.         query();
17.        //提示对话框
18.        final AlertDialog.Builder builder = new AlertDialog.Builder(this);
19.        listView.setOnItemClickListener(new OnItemClickListener() {
20.            @Override
21.            public void onItemClick(AdapterView<?> parent, View view,
22.                    int position, long id) {
23.                final long temp = id;
24.                builder.setMessage("真的要删除该条记录吗？").setPositiveButton("是", new DialogInterface.OnClickListener() {
25.
26.                    @Override
27.                    public void onClick(DialogInterface dialog, int which) {
28.                        System.out.println("yes");
29.                        help.del((int)temp);
30.                        //重新查询
31.                        //query();
32.                        Cursor c = help.query();
33.                        //列表项数组
34.                        String[] from ={"_id","name","url","desc"};
35.                        //列表项ID
36.                        int[] to ={R.id.text0,R.id.text1,R.id.text2,R.id.text3};
37.                        //适配器
38.                        SimpleCursorAdapter adapter = new SimpleCursorAdapter(getApplicationContext(),R.layout.row,c,from,to);
39.                        ListView listView = getListView();
40.                        listView.setAdapter(adapter);
41.
42.
43.                    }
44.                }).setNegativeButton("否", new DialogInterface.OnClickListener() {
45.
46.                    @Override
47.                    public void onClick(DialogInterface dialog, int which) {
48.                        // TODO Auto-generated method stub
49.
50.                    }
51.                });
52.                builder.create();
53.                builder.show();
54.            }
55.        });
56.
57.    }
58.    @Override
59.    protected void onStop() {
60.        // TODO Auto-generated method stub
61.        super.onStop();
62.
63.    }
64.    public void query(){
65.        //列表项数组
66.        String[] from ={"_id","name","url","desc"};
67.        //列表项ID
68.        int[] to ={R.id.text0,R.id.text1,R.id.text2,R.id.text3};
69.
70.        //适配器
71.        SimpleCursorAdapter adapter = new SimpleCursorAdapter(this,R.layout.row,c,from,to);
72.        //adapter.notifyDataSetChanged();
73.        //列表视图
74.         listView = getListView();
75.        //为列表视图添加适配器
76.        listView.setAdapter(adapter);
77.
78.    }
79.
80.
81.}

DBHelper.java

view plaincopy to clipboardprint?
01.public class DBHelper extends SQLiteOpenHelper {
02.
03.    private static final String DB_NAME="coll.db";
04.    //表名
05.    private static final String TBL_NAME="logtable";
06.    //创建SQL语句
07.    private static final String CREATE_TBL = "create table logtable " +
08.            "(_id integer primary key autoincrement,name text,url text,desc text)";
09.    //SQLiteDatabase实例
10.    private SQLiteDatabase db;
11.
12.    public DBHelper(Context context) {
13.        super(context, DB_NAME, null, 2);
14.
15.    }
16.    @Override
17.    public void onCreate(SQLiteDatabase db) {
18.
19.        db.execSQL(CREATE_TBL);
20.    }
21.
22.    //打开数据库
23.    public void open(){
24.        db = getWritableDatabase();
25.    }
26.
27.    @Override
28.    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
29.        // TODO Auto-generated method stub
30.    }
31.
32.    //插入方法
33.    public void insert(ContentValues values){
34.
35.        db.insert(TBL_NAME, null, values);
36.    }
37.
38.    //查询方法
39.    public Cursor query(){
40.        Cursor c = db.query(TBL_NAME, null, null, null, null, null, null);
41.        return c;
42.    }
43.
44.    //删除方法
45.    public void del(int id){
46.        db.delete(TBL_NAME, "_id=?", new String[]{String.valueOf(id)});
47.    }
48.
49.    //关闭数据库
50.    public void close(){
51.        if (db != null){
52.            db.close();
53.        }
54.    }
55.}

main_1.xml

view plaincopy to clipboardprint?
01.<?xml version="1.0" encoding="UTF-8"?>
02.<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
03.    android:orientation="vertical"
04.    android:layout_width="fill_parent"
05.    android:layout_height="fill_parent"
06.    >
07.
08.    <TextView
09.        android:id="@+id/TextView01"
10.        android:layout_width="fill_parent"
11.        android:layout_height="wrap_content"
12.        android:text="网站名称"
13.    />
14.    <EditText
15.        android:id="@+id/EditText01"
16.        android:layout_width="fill_parent"
17.        android:layout_height="wrap_content"
18.
19.    />
20.    <TextView
21.        android:id="@+id/TextView02"
22.        android:layout_width="fill_parent"
23.        android:layout_height="wrap_content"
24.        android:text="URL"
25.    />
26.    <EditText
27.        android:id="@+id/EditText02"
28.        android:layout_width="fill_parent"
29.        android:layout_height="wrap_content"
30.    />
31.    <TextView
32.        android:id="@+id/TextView03"
33.        android:layout_width="fill_parent"
34.        android:layout_height="wrap_content"
35.        android:text="网站描述"
36.    />
37.    <EditText
38.        android:id="@+id/EditText03"
39.        android:layout_width="fill_parent"
40.        android:layout_height="wrap_content"
41.        android:height="100px"
42.    />
43.
44.    <Button
45.        android:id="@+id/button"
46.        android:layout_width="wrap_content"
47.        android:layout_height="wrap_content"
48.        android:text="添加"
49.    />
50.</LinearLayout>

自定义布局：row.xml

结果如图所示：