Json解析小案例

本文Json解析荔枝新闻

MainActivity中的代码：

package org.moblie.train.zday09_json;

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

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import org.moblie.train.zday09_json_MyUtils.HttpURLConnHelper;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ListView;
import android.widget.Toast;

public class MainActivity extends Activity {
private String jsonUrl = "http://litchiapi.jstv.com/api/GetFeeds?column=0&PageSize=20&pageIndex=";
private ListView listView;
private MyAdapter adapter;
private List<Map<String, String>> list = new ArrayList<Map<String, String>>();
private boolean isBottom;
private int currentPage = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// 初始化ListView
initViews();
// 完成网络请求，通过异步任务，在子线程完成
loadNetworkData();
}

private void loadNetworkData() {
new MyTask().execute(jsonUrl + currentPage);
}

private void initViews() {
listView = (ListView) findViewById(R.id.listView_Main);
adapter = new MyAdapter(list, this);
listView.setAdapter(adapter);
listView.setOnScrollListener(new OnScrollListener() {

@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
if (isBottom && scrollState == SCROLL_STATE_IDLE) {
// 已经滑动到最底部。此时需要将页数加1，再重新请求
currentPage++;
loadNetworkData();
}
}

@Override
public void onScroll(AbsListView view, int firstVisibleItem,
int visibleItemCount, int totalItemCount) {
isBottom = ((firstVisibleItem + visibleItemCount) == totalItemCount);
}
});
}

public List<Map<String, String>> jsonStringToList(String jsonString) {
try {
JSONObject jsonObject = new JSONObject(jsonString);
if (jsonObject.getString("status").equals("ok")) {
JSONObject jsonObject_paramz = jsonObject
.getJSONObject("paramz");
JSONArray jsonArray_feeds = jsonObject_paramz
.getJSONArray("feeds");
// 解析JSONArray要遍历
for (int i = 0; i < jsonArray_feeds.length(); i++) {
JSONObject jsonObject_feed = jsonArray_feeds
.getJSONObject(i);
JSONObject jsonObject_data = jsonObject_feed
.getJSONObject("data");
String jsonString_subject = jsonObject_data
.getString("subject");
String jsonString_summary = jsonObject_data
.getString("summary");
Map<String, String> map = new HashMap<String, String>();
map.put("subject", jsonString_subject);
map.put("summary", jsonString_summary);
list.add(map);
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return list;
}

class MyTask extends AsyncTask<String, Integer, List<Map<String, String>>> {

@Override
// 在子线程中完成的方法
protected List<Map<String, String>> doInBackground(String... params) {
// 网络请求返回的byte数组
// 参数即URL
/**
[此处用到的网络请求工具类详见博客](http://blog.csdn.net/iblade/article/details/50488749)
*/
byte[] data = HttpURLConnHelper.loadByteFromURL(params[0]);
if (data != null) {
String jsonString = new String(data);
List<Map<String, String>> li = jsonStringToList(jsonString);
return li;
} else {// 如果data为空，即网络数据请求失败
Toast.makeText(MainActivity.this, "网络异常，请检查网络",
Toast.LENGTH_SHORT);
}
return null;
}

@Override
protected void onPostExecute(List<Map<String, String>> li) {
super.onPostExecute(li);
list.addAll(li);
adapter.notifyDataSetChanged();
}
}
}

MyAdapter中的代码：

package org.moblie.train.zday09_json;

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

import android.app.Activity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.TextView;

public class MyAdapter extends BaseAdapter {
private List<Map<String, String>> list;
private Activity activity;

public MyAdapter(List<Map<String, String>> list, Activity activity) {
super();
this.list = list;
this.activity = activity;
}

@Override
public int getCount() {
return list.size();
}

@Override
public Object getItem(int position) {
return list.get(position);
}

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

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = null;
if (convertView == null) {
holder = new ViewHolder();
convertView = activity.getLayoutInflater().inflate(
R.layout.item_listview_main, parent, false);
holder.subjectView = (TextView) convertView
.findViewById(R.id.textSuject);
holder.summaryView = (TextView) convertView
.findViewById(R.id.textSummary);
convertView.setTag(holder);
} else {
holder = (ViewHolder) convertView.getTag();
}
holder.subjectView.setText(list.get(position).get("subject"));
holder.summaryView.setText(list.get(position).get("summary"));

return convertView;
}

class ViewHolder {
private TextView subjectView;
private TextView summaryView;

}
}

item_listview_activity.xml中的代码：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal" >

<TextView
android:id="@+id/textSuject"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="标题" />

<TextView
android:id="@+id/textSummary"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="内容" />

</LinearLayout>

activity_main.xml中代码：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<ListView
android:id="@+id/listView_Main"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</ListView>

</LinearLayout>

我们的数据源来自网络

所以一定不要忘了在清单文件中为其设置连接网络权限

清单文件中的代码：

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="14" />
<uses-permission android:name="android.permission.INTERNET"/>