spinner 从数据库读取数据并实现二级联动。
这里主要实现了。省份和城市的二级关联。选择省份。二级对应的就是省份所有的城市

下面看代码；
        1.activity
        @Override
        protected void onCreate(Bundle savedInstanceState) {
                // TODO Auto-generated method stub
                super.onCreate(savedInstanceState);
                setContentView(R.layout.test_layout);
                this.mContext = this;
                Map<Integer,List> data = ProvinceDB.getProvince();//得到数据库数据
                provinceList = data.get(1);
                provinceData = data.get(0);
               
                ArrayAdapter provinceAdapter = new ArrayAdapter(mContext,android.R.layout.simple_spinner_item,provinceList);
                provinceAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); // 样式
               
                spProvince.setAdapter(provinceAdapter);
                spProvince.setOnItemSelectedListener(itemSelectedListener);
               
        }
       
        // 选择省份 联动 对应城市
        private OnItemSelectedListener itemSelectedListener = new OnItemSelectedListener() {
                @Override
                public void onItemSelected(AdapterView<?> parent, View view,
                                int position, long id) {
                        Spinner spProvince = (Spinner) parent;
                        String selProvince = (String) spProvince.getItemAtPosition(position);
                        ArrayAdapter cityAdapter = null;
                        Map<String,Integer> data = (Map)provinceData.get(position);//根据所选择的得到对应的省份id 然后得到城市
                        int pid = data.get(selProvince);//得到省份的id
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