Android项目开发全程(四)-- 将网络返回的json字符串轻松转换成listview列表

  前面几篇博文介绍了从项目搭建到获取网络字符串,对一个项目的前期整体工作进行了详细的介绍,本篇接着上篇介绍一下怎么样优雅将网络返回的json字符串轻松转换成listview列表。

  先上图,看一下效果。

                

  包括下拉刷新和上拉加载更多两个功能,怎样还算可以吧~,比起前几篇博文中的那一大片一大片的“乱码”看起来是不是舒服多了。

一、对界面面布局

  1、Android默认的标题栏不太好看,咱们需要换成自己的。在AndroidManifest.xml文件中将APP主题设为NoTitleBar

1 <application
2         android:allowBackup="true"
3         android:icon="@drawable/ic_launcher"
4         android:label="@string/app_name"
5         android:theme="@android:style/Theme.NoTitleBar" >
6 </application>

  2、然后在每个局部文件中加上自己创建的标题,为了以后便于管理,最好将标题作为一个单独的布局文件(title_layout.xml),然后通过include引用。

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="44dp"
 5     android:orientation="horizontal" >
 6     <TextView
 7         android:id="@+id/app_title"
 8         android:layout_width="fill_parent"
 9         android:layout_height="44dp"
10         android:gravity="center"
11         android:background="#FFA500"
12         android:textColor="#FFF"
13         android:textSize="20dp"
14         android:text="@string/app_name" />
15 </LinearLayout>

  3、创建主界面(activity_main.xml)

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:background="#ededed"
 6     android:orientation="vertical" >
 7     <!--引用标题栏-->
 8     <include layout="@layout/title_layout"/>
 9     <!-- 第三方类库的listview,可下拉刷新,上拉加载更多 -->
10     <com.handmark.pulltorefresh.library.PullToRefreshListView
11         android:id="@+id/pull_refresh_list"
12         android:layout_width="fill_parent"
13         android:layout_height="fill_parent"
14         android:layout_weight="1.0"
15         android:layout_marginTop="3dp"
16         android:cacheColorHint="#00000000"
17         android:divider="@null"
18         android:fadingEdge="none"
19         android:fastScrollEnabled="false"
20         android:footerDividersEnabled="false"
21         android:headerDividersEnabled="false"
22         android:scrollbars="none"
23         android:smoothScrollbar="true"/>
24 </LinearLayout>

  这里通过include引用了title_layout.xml文件,listview控件使用的第三方类库PullToRefresh,下载时会一并给出。

  4、创建listview的item布局(item_main.xml)

 1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="wrap_content"
 5     android:paddingTop="3dp"
 6     android:paddingBottom="3dp"
 7     android:paddingLeft="8dp"
 8     android:paddingRight="8dp"
 9     android:orientation="vertical" >
10     
11     <LinearLayout 
12         android:layout_width="match_parent"
13         android:layout_height="wrap_content"
14         android:padding="10dp"
15         android:background="@drawable/bg_shape"
16         android:orientation="vertical" >
17 
18         <TextView
19             android:id="@+id/tv_title"
20             android:layout_width="fill_parent"
21             android:layout_height="wrap_content"
22             android:singleLine="true"
23             android:textColor="#3b3d42"
24             android:textSize="16dp" />
25 
26         <TextView
27             android:id="@+id/tv_time"
28             android:layout_width="fill_parent"
29             android:layout_height="wrap_content"
30             android:layout_marginTop="3dp"
31             android:textColor="#636251"
32             android:textSize="12dp" />
33         <TextView
34             android:id="@+id/tv_content"
35             android:layout_width="fill_parent"
36             android:layout_height="wrap_content"
37             android:textColor="#636251"
38             android:textSize="16dp"
39             android:layout_marginTop="8dp" />
40     </LinearLayout>
41 </LinearLayout>

二、创建Adapter(MainAdapter.java)

 1 public class MainAdapter extends BaseAdapter {
 2     private Context context;
 3     private List<Map<String, Object>> list;
 4     private LayoutInflater inflater;
 5     public MainAdapter(Context context, List<Map<String, Object>> list) {
 6         this.context = context;
 7         inflater = inflater.from(context);
 8         this.list = list;
 9     }
10     @Override
11     public int getCount() {
12         return list.size();
13     }
14 
15     @Override
16     public Object getItem(int arg0) {
17         return list.get(arg0);
18     }
19 
20     @Override
21     public long getItemId(int arg0) {
22         return arg0;
23     }
24 
25     @Override
26     public View getView(int position, View convertView, ViewGroup parent) {
27         Holder holder = null;
28         Map<String, Object> map = list.get(position);
29         if(holder == null){
30             holder = new Holder();
31             convertView = inflater.inflate(R.layout.item_main, null);
32             holder.title = (TextView) convertView.findViewById(R.id.tv_title);
33             holder.time = (TextView) convertView.findViewById(R.id.tv_time);
34             holder.content = (TextView) convertView.findViewById(R.id.tv_content);
35             convertView.setTag(holder);
36         }
37         holder.title.setText(map.get("title").toString());
38         holder.time.setText(map.get("publishDate").toString());
39         holder.content.setText(map.get("content").toString());
40         return convertView;
41     }
42     
43     class Holder {
44         public TextView title;
45         public TextView time;
46         public TextView content;
47     }
48 }

 

  这里的MainAdapter继承了BaseAdapter,为listview提供适配器。

三、在MainActivity操作数据(分步讲解)

  1、初始化pullRefreshList(是一个PullToRefreshListView,第三方类库PullToRefresh,可上拉刷新,下拉加载更多)

 1 //初始化pullRefreshList
 2     public void initListView(){
 3         pullRefreshList.setMode(Mode.BOTH);
 4         layoutProxy = pullRefreshList.getLoadingLayoutProxy(true, false);
 5         layoutProxy.setPullLabel("下拉刷新");
 6         layoutProxy.setReleaseLabel("松开立即刷新");
 7         layoutProxy.setRefreshingLabel("正在载入");
 8         layoutProxybottom = pullRefreshList.getLoadingLayoutProxy(false, true);
 9         layoutProxybottom.setPullLabel("上拉加载更多");
10         layoutProxybottom.setReleaseLabel("松开立即刷新");
11         layoutProxybottom.setRefreshingLabel("正在载入");
12         pullRefreshList.setOnRefreshListener(new MyRefresh());
13         listView = pullRefreshList.getRefreshableView();
14         lists = new ArrayList<Map<String,Object>>();
15         adapter = new MainAdapter(getApplicationContext(), lists);
16         listView.setAdapter(adapter);
17     }

  2、设置pullRefreshList的刷新监听器,当上拉是表示刷新,将参数page设为第一页,提交请求。当下拉时表示加载更多,将page+1,然后提交请求。

 1 class MyRefresh implements OnRefreshListener2<ListView>{
 2     //上拉是回调此方法
 3         @Override
 4         public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
 5             page = 1;
 6             getNetData.getLaughBy360(REQUEST_360LAUGH_CODE, page + "");
 7         }
 8     //下拉时回调此方法
 9         @Override
10         public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
11             if(page < 34){  //目前接口中一个有34页数据
12                 page += 1;
13                 getNetData.getLaughBy360(REQUEST_360LAUGH_CODE, page + "");
14                 mHandler.sendEmptyMessage(DIALOG_SHOW);
15             } else {
16                 pullRefreshList.onRefreshComplete();
17                 Toast.makeText(getApplicationContext(), "已经是最后一页了", Toast.LENGTH_SHORT).show();
18             }
19         }
20     }

  3、在网络请求的回调方法中,利用jackson工具的ObjectMapper可以很容易的将json字符串转换成Map(也可根据需要转换成List、对象等等)

 1 public void onCallBackSuccessed(int notify, String result) {
 2         if(notify == REQUEST_360LAUGH_CODE){
 3             try {
 4                 //使用Jackson工具的ObjectMapper直接将json字符串转换成Map格式
 5                 Map<String, Object> map = objectMapper.readValue(result, Map.class);
 6                 List<Map<String, Object>> list = (List<Map<String, Object>>) map.get("jokes");
 7                 if(page == 1) {
 8                     lists.clear();
 9                 }
10                 if(list.size() == 0){
11                     Toast.makeText(getApplicationContext(), "木有笑话了", Toast.LENGTH_SHORT).show();
12                 } else {
13                     lists.addAll(list);
14                     //改变adapter数据
15                     adapter.notifyDataSetChanged();
16                 }
17             } catch (JsonParseException e) {
18                 e.printStackTrace();
19             } catch (JsonMappingException e) {
20                 e.printStackTrace();
21             } catch (IOException e) {
22                 e.printStackTrace();
23             }
24         }
25         mHandler.sendEmptyMessage(DIALOG_CONCEL);
26         pullRefreshList.onRefreshComplete();
27     }

 

  分析一下,这里每次从网络上获取的结果转成后都先加入到一个临时的list中,当page=1时,说明此事是上拉刷新或者首次请求。这时候将直接将lists清空来接受最新数据,当page !=1 时说明是加载更多的请求,无需清空lists,如果新返回的数据不为空则将list加入到lists中,然后通知adapter数据改变。

  别忘了设置onRefreshComplete完成刷新状态。

  最后,整个的MainActivity.java如下:

  1 package com.laughdemo.main;
  2 import java.io.IOException;
  3 import java.util.ArrayList;
  4 import java.util.List;
  5 import java.util.Map;
  6 import net.tsz.afinal.annotation.view.ViewInject;
  7 import org.codehaus.jackson.JsonParseException;
  8 import org.codehaus.jackson.map.JsonMappingException;
  9 import android.os.Bundle;
 10 import android.widget.ListView;
 11 import android.widget.Toast;
 12 import com.handmark.pulltorefresh.library.ILoadingLayout;
 13 import com.handmark.pulltorefresh.library.PullToRefreshBase;
 14 import com.handmark.pulltorefresh.library.PullToRefreshBase.Mode;
 15 import com.handmark.pulltorefresh.library.PullToRefreshBase.OnRefreshListener2;
 16 import com.handmark.pulltorefresh.library.PullToRefreshListView;
 17 import com.laughdemo.adapter.MainAdapter;
 18 import com.laughdemo.http.DataCallBack;
 19 import com.laughdemo.http.GetNetData;
 20 import com.laughdemo.utils.Constants;
 21 /**
 22  * 主窗体类
 23  * @author 刘伟 2015.7.3
 24  */
 25 public class MainActivity extends BaseActivity implements Constants, DataCallBack{
 26     final String TAG = "MainActivity";
 27     GetNetData getNetData;
 28     MainAdapter adapter;
 29     private int page = 1;
 30     ListView listView;
 31     List<Map<String, Object>> lists;
 32     private ILoadingLayout layoutProxy;
 33     private ILoadingLayout layoutProxybottom;
 34     @ViewInject(id=R.id.pull_refresh_list) PullToRefreshListView pullRefreshList;
 35     @Override
 36     protected void onCreate(Bundle savedInstanceState) {
 37         super.onCreate(savedInstanceState);
 38         setContentView(R.layout.activity_main);
 39         initListView();
 40         getNetData = new GetNetData(this);
 41         getNetData.getLaughBy360(REQUEST_360LAUGH_CODE, page + "");
 42         mHandler.sendEmptyMessage(DIALOG_SHOW);
 43     }
 44     
 45     //初始化pullRefreshList
 46     public void initListView(){
 47         pullRefreshList.setMode(Mode.BOTH);
 48         layoutProxy = pullRefreshList.getLoadingLayoutProxy(true, false);
 49         layoutProxy.setPullLabel("下拉刷新");
 50         layoutProxy.setReleaseLabel("松开立即刷新");
 51         layoutProxy.setRefreshingLabel("正在载入");
 52         layoutProxybottom = pullRefreshList.getLoadingLayoutProxy(false, true);
 53         layoutProxybottom.setPullLabel("上拉加载更多");
 54         layoutProxybottom.setReleaseLabel("松开立即刷新");
 55         layoutProxybottom.setRefreshingLabel("正在载入");
 56         pullRefreshList.setOnRefreshListener(new MyRefresh());
 57         listView = pullRefreshList.getRefreshableView();
 58         lists = new ArrayList<Map<String,Object>>();
 59         adapter = new MainAdapter(getApplicationContext(), lists);
 60         listView.setAdapter(adapter);
 61     }
 62     
 63     class MyRefresh implements OnRefreshListener2<ListView>{
 64 
 65         @Override
 66         public void onPullDownToRefresh(PullToRefreshBase<ListView> refreshView) {
 67             page = 1;
 68             getNetData.getLaughBy360(REQUEST_360LAUGH_CODE, page + "");
 69         }
 70 
 71         @Override
 72         public void onPullUpToRefresh(PullToRefreshBase<ListView> refreshView) {
 73             if(page < 34){
 74                 page += 1;
 75                 getNetData.getLaughBy360(REQUEST_360LAUGH_CODE, page + "");
 76                 mHandler.sendEmptyMessage(DIALOG_SHOW);
 77             } else {
 78                 pullRefreshList.onRefreshComplete();
 79                 Toast.makeText(getApplicationContext(), "已经是最后一页了", Toast.LENGTH_SHORT).show();
 80             }
 81         }
 82     }
 83     @Override
 84     public void onCallBackSuccessed(int notify, String result) {
 85         if(notify == REQUEST_360LAUGH_CODE){
 86             try {
 87                 //使用Jackson工具的ObjectMapper直接将json字符串转换成Map格式
 88                 Map<String, Object> map = objectMapper.readValue(result, Map.class);
 89                 List<Map<String, Object>> list = (List<Map<String, Object>>) map.get("jokes");
 90                 if(page == 1) {
 91                     lists.clear();
 92                 }
 93                 if(list.size() == 0){
 94                     Toast.makeText(getApplicationContext(), "木有笑话了", Toast.LENGTH_SHORT).show();
 95                 } else {
 96                     lists.addAll(list);
 97                     //改变adapter数据
 98                     adapter.notifyDataSetChanged();
 99                 }
100             } catch (JsonParseException e) {
101                 e.printStackTrace();
102             } catch (JsonMappingException e) {
103                 e.printStackTrace();
104             } catch (IOException e) {
105                 e.printStackTrace();
106             }
107         }
108         mHandler.sendEmptyMessage(DIALOG_CONCEL);
109         pullRefreshList.onRefreshComplete();
110     }
111     @Override
112     public void onCallBackFailed(int notify) {
113         mHandler.sendEmptyMessage(DIALOG_CONCEL);
114         pullRefreshList.onRefreshComplete();
115         Toast.makeText(getApplicationContext(), "网络连接失败", Toast.LENGTH_LONG).show();
116     }
117 }

 

 

到这里,这个小项目的整个流程也可以算是介绍完了。有需要项目源码的可以直接留下邮箱索要,也可以去下载:http://download.csdn.net/detail/u012950035/8871581

本篇博文是在前几篇的基础上接着做的,如有不明白的地方还需参考前几篇:

posted @ 2015-07-05 23:22  codingblock  阅读(3043)  评论(9编辑  收藏  举报