Android 系列笔记 三

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单元测试

  • 新建一个类继承自AndroidTestCase，并实现自己的测试方法

  • 在配置清单文件中添加

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    <instrumentation
    	android:name="android.test.InstrumentationTestRunner" 
    	android:targetPackage="要测试程序的包名" />

  • 在application节点下添加

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    <uses-library android:name="android.test.runner" />

SQLite 数据库的创建

1.定义一个类继承自SQLiteOpenHelper
实现其构造函数及onCreate() onUpgrade()方法
super(Context context, String name, CursorFactory factory, int version)
分别为 上下文 数据库文件名 游标工厂(默认为空) 版本号
在onCreate()方法中初始化表 该方法在数据库第一次创建时调用
onUpgrade()方法在数据库版本升级时调用
2.定义一个Dao类实现数据库的管理
新建一个上面帮助类变量，实现自己的构造方法，然后实现数据库管理功能

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void insert(Person person){
	SQLiteDatabase db = openHelper.getWritableDatabase();
	if(db.isOpen()){ //如果数据库已打开 执行数据的插入
		//直接拼接SQL语句不安全，存在SQL注入
		String sql = "insert into person(name, age) values(?,?);";
		db.execSQL(sql, new Object[]{person.getName(), person.getAge()});
		Log.v("INFO", "已插入一条数据 " + person.toString());
		db.close();
}

void delete(int id){
	SQLiteDatabase db = openHelper.getWritableDatabase();
	if(db.isOpen()){
		db.execSQL("delete from person where _id = ?", new Object[]{id});
		db.close();
		Log.v("INFO", "已删除数据  id = " + id);
	}
}

void update(String name,int id){
	SQLiteDatabase db = openHelper.getWritableDatabase();
	if(db.isOpen()){
		db.execSQL("update person set name=? where _id=?", new Object[]{name,id});
		db.close();
		Log.v("INFO", "已更新数据  id="+id+", name=" + name);
	}
}

List<Person> queryAll(){
	List<Person> personList = null;
	SQLiteDatabase db = openHelper.getReadableDatabase();
	Cursor cursor = db.rawQuery("select _id, name, age from person", null);
	Person person = null;
		
	if(cursor != null && cursor.getCount() > 0){
		personList = new ArrayList<Person>();
		while(cursor.moveToNext()){
			person = new Person();
			person.setId(cursor.getInt(0));
			person.setName(cursor.getString(1));
			person.setAge(cursor.getInt(2));
			personList.add(person);
			Log.v("INFO", "查询数据:" + person.toString());
		}
		cursor.close();//数据库优化 使用完要记得关闭
		db.close();
	}
	return personList;
}

Person query(int id){
	Person person = null;
	SQLiteDatabase db = openHelper.getReadableDatabase();
	Cursor cursor = db.rawQuery("select _id, name, age from person where _id=?", new String[]{String.valueOf(id)});
		
	if(cursor != null && cursor.moveToFirst()){
		person = new Person();
		person.setId(cursor.getInt(0));
		person.setName(cursor.getString(1));
		person.setAge(cursor.getInt(2));
		Log.v("INFO", "查询数据:" + person.toString());
		cursor.close();
		db.close();
	}
	return person;
}

java API 实现数据库增删改查

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void insert(Person person){
	SQLiteDatabase db = openHelper.getWritableDatabase();
	ContentValues values = null;
	if(db.isOpen()){
		values = new ContentValues();
		values.put("name", person.getName());
		values.put("age", person.getAge());
		long row=db.insert("person", null, values);
		Log.v("INFO", "第"+row+"行受影响," + person.toString());
		db.close();
	}
}

void delete(int id){
	SQLiteDatabase db = openHelper.getWritableDatabase();
	if(db.isOpen()){
		long count = db.delete("person", "_id=?", new String[]{String.valueOf(id)});
		Log.v("INFO", "删除数据:" + count + "行受影响,");
		db.close();
	}
}

void update(String name,int id){
	SQLiteDatabase db = openHelper.getWritableDatabase();
	ContentValues values = null;
	if(db.isOpen()){
		values = new ContentValues();
		values.put("name", name);
		long count = db.update("person", values, "_id=?", new String[]{String.valueOf(id)});
		Log.v("INFO", "更新数据:" + count + "行受影响,");
		db.close();
	}
}

List<Person> queryAll(){
	List<Person> personList = null;
	Person person = null;
	SQLiteDatabase db = openHelper.getReadableDatabase();
	if(db.isOpen()){
		personList = new ArrayList<Person>();
		String[] columns = new String[]{"_id", "name", "age"};//需要查询的列
		String selection = null;//选择条件为空  查询所有 
		String[] selectionArgs = null;//选择条件参数
		String groupBy = "name";//分组查询 group by name
		String having = null;//过滤语句
		String orderBy = null;//排序
		Cursor cursor = db.query("person", columns, selection, selectionArgs, groupBy, having, orderBy);
		if(cursor != null && cursor.getCount() > 0){
			while(cursor.moveToNext()){
				person = new Person();
				person.setName(cursor.getString(1));
				person.setAge(cursor.getInt(2));
				personList.add(person);
			}
		}
		cursor.close();
		db.close();
	}
	return personList;
}

Person queryItem(int id){
	Person person = null;
	SQLiteDatabase db = openHelper.getReadableDatabase();
	if(db.isOpen()){
		String[] columns = new String[]{"_id", "name", "age"};//需要查询的列
		String selection = "_id=?";//选择条件为空  查询所有 
		String[] selectionArgs = new String[]{String.valueOf(id)};//选择条件参数
		String groupBy = "name";//分组查询 group by name
		String having = null;//过滤语句
		String orderBy = null;//排序
		Cursor cursor = db.query("person", columns, selection, selectionArgs, groupBy, having, orderBy);
		if(cursor != null && cursor.moveToFirst()){
			person = new Person();
			person.setName(cursor.getString(1));
			person.setAge(cursor.getInt(2));
		}
		cursor.close();
		db.close();
	}
	return person;
}

SQLite3的使用

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adb shell
ls //列出当前目录下文件与文件夹
cd /data/data/包名
cd databases

sqlite3 数据库文件名
select * from person;
delete from person where _id=3;

.table //列出数据库中表名
.mode column //更改输出模式
.exit //退出SQLite3

SQLite事务操作

要知道开启事务操作，效率要比不开启提升了10倍左右

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void testTransaction(){
	SQLiteDatabase db = openHelper.getWritableDatabase();
		
	if(db.isOpen()){
		try{
			//开启事务
			db.beginTransaction();
				
			String sql = "update person set balance=balance-1000 where name='ai';";
			db.execSQL(sql);
				
			//double i = 10/0;
				
			String sql2 = "update person set balance=balance+1000 where name='zhangsan';";
			db.execSQL(sql2);
				
			//标记事务成功
			db.setTransactionSuccessful();
		}catch(Exception e){
			e.printStackTrace();
		}finally{
			//关闭事务
			db.endTransaction();
			db.close();
		}
	}
}

ListView

自定义适配器一

getView()方法返回的为TextView

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class MyAdapter extends BaseAdapter{
	@Override
	public int getCount() {
		return personList.size();
	}

	@Override
	public Object getItem(int position) {
		return null;
	}

	@Override
	public long getItemId(int position) {
		return 0;
	}

    /**
	* 返回的是ListView中某一行view对象
	* position 当前返回的view的索引位置
	* convertView 缓存对象
	* parent ListView对象
	*/
	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		TextView tv = null;
			
		//向下滚动 上面内容消失后会被缓存
		if(convertView != null){//复用缓存对象优化ListView
			tv = (TextView) convertView;
			Log.v("INFO", "复用：" + position);
		}else{
			tv = new TextView(getApplicationContext());
			Log.v("INFO", "新建：" + position);
		}
			
		tv.setTextSize(30);
		tv.setTextColor(Color.BLACK);
		Person person = personList.get(position);
		tv.setText(person.toString());
		return tv;
	}
}

自定义适配器二

getView()方法返回的为Layout布局

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class MyAdapter_2 extends BaseAdapter{
	@Override
	public int getCount() {
		return personList.size();
	}

	@Override
	public Object getItem(int position) {
		return null;
	}

	@Override
	public long getItemId(int position) {
		return 0;
	}

	/**
	* 返回的是ListView中某一行view对象
	* position 当前返回的view的索引位置
	* convertView 缓存对象
	* parent ListView对象
	*/
	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		View view = null;
		LayoutInflater inflater = null;
		if(convertView != null){
			view = convertView;
			Log.v("INFO", "复用：" + position);
		}else{
			//将布局文件转换为一个对象
			inflater = MainActivity.this.getLayoutInflater();
			view = inflater.inflate(R.layout.adapter2_itemlist, null);
			Log.v("INFO", "新建：" + position);
		}
			
		TextView name_textview = (TextView)view.findViewById(R.id.name_view);
		TextView age_textview = (TextView)view.findViewById(R.id.age_view);
		Person person = personList.get(position);
		name_textview.setText(person.getName());
		age_textview.setText(person.getAge() + "");
		return view;
	}
}

ListView 绑定ArrayAdapter适配器

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String[] persons = new String[]{"A","B","C","D","E","F","G","H"};
arrayAdapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_list_item_1, persons);

ListView 绑定SimpleAdapter适配器

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data = new ArrayList<Map<String,Object>>();
for(Person person : personList){
	Map<String,Object> map = new HashMap<String, Object>();
	map.put("name", person.getName());
	map.put("age", person.getAge());
	data.add(map);
}
String[] from = new String[]{"name", "age"};
int[] to = new int[]{R.id.title_textview, R.id.subtitle_textview};
adapter = new SimpleAdapter(getApplicationContext(), data, R.layout.item_list, from, to);

ListView动态更新

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adapter.notifyDataSetChanged();

对话框

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AlertDialog.Builder builder = new Builder(this);
builder.setIcon(android.R.drawable.alert_dark_frame)
    .setTitle("Title")
    .setMessage("message")
    .setPositiveButton("确定", new OnClickListener(){
        @Override
        public void onClick(DialogInterface dialog, int which){
            Toast.makeText(MainActivity.this, "确定", Toast.LENGTH_SHORT).show();
        }
    })
    .setNegativeButton("取消", new OnClickListener(){
        @Override
        public void onClick(DialogInterface dialog, int which){
            Toast.makeText(MainActivity.this, "取消", Toast.LENGTH_SHORT).show();
        }
    });
builder.create().show();

单选对话框

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final String[] items = new String[]{"男", "女"};
AlertDialog.Builder builder = new Builder(this);
builder.setTitle("请选择性别")
    .setSingleChoiceItems(items, -1, new OnClickListener(){
        @Override
        public void onClick(DialogInterface dialog, int which){
            Toast.makeText(MainActivity.this, "您选择的是" + items[which], Toast.LENGTH_SHORT).show();
            dialog.dismiss();
        }
    });
builder.create().show();

多选会话框

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final String[] items = new String[]{"蓝莓", "西瓜", "香蕉", "苹果"};
boolean[] checkedItems = new boolean[]{true, true, true, false};
AlertDialog.Builder builder = new Builder(this);
builder.setTitle("请选择你喜欢的水果")
    .setMultiChoiceItems(items, checkedItems, new OnMultiChoiceClickListener(){
        @Override
        public void onClick(DialogInterface dialog, int which, boolean isChecked){
            checkedItems[which] = isChecked;
        }
    })
    .setPositiveButton("确定", new OnClickListener(){
        @Override
        public void onClick(DialogInterface dialog, int which){
            Toast.makeText(MainActivity.this, "你选择的是：", Toast.LENGTH_SHORT).show();
            dialog.dismiss();
        }
    });
builder.create().show();