Gson的使用——Gson解析json陣列並展示在ListView控制元件上
阿新 • • 發佈：2019-02-05
類似於解析json資料的框架有很多，常用的就是Gson，使用起來特別的方便，同時，還擁有很好的可操作性，今天就來說說怎麼用Gson去解析一個json陣列。使用Gson之前，需要下載一個gson.jar的jar包。具體的自己去網上下載，有很多。
首先看看資料來源
{
"a": [
{
"numid": "1",
"name": "艾勇",
"abbreviation": "aiyong",
"photo": "/test/qingqixie/Public/Upload/niul7b2sdy.jpg" 這個是一個比較具有代表性的json資料。先大體的分析一下資料，最外面的是一個json物件，裡面有四個json陣列。那麼進行第一、步，先建立實體類，當然了，這麼多的資料，不可能讓我們一個個的去寫，我們這裡要引用一個工具，他會幫我生成實體類。
網址如下：http://www.bejson.com/json2javapojo/
這裡為了方便，我就把這個資料放在了assets目錄下，取名為text.txt 。
好了，資料來源有了，實體類也建好了，那麼就可以開始我們的編碼了。首先是從assets取出資料，程式碼如下：
try {
String data;
InputStream is;
is=getResources().getAssets().open("text.txt");
byte[] b = new byte[is.available()];
is.read(b);
data = new String(b);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}這個data就是我們的json資料了，接下來就是實現解析的操作了。這裡我寫成了一個方法。具體程式碼如下：
/*
* 解析資料
*/
public void analysisData(String data) {
try {
// Type listType = new TypeToken<List<Root>>() {
// }.getType();
oList = new ArrayList<Map<String, Object>>();
List<Root> appinfos = new ArrayList<Root>();
Root depts = gson.fromJson(data, Root.class);
appinfos.add(depts);
for (int i = 0; i < appinfos.size(); i++) {
root = appinfos.get(i);
List<A> listA = new ArrayList<A>();
List<B> listB = new ArrayList<B>();
listA = root.getA();
for (int j = 0; j < listA.size(); j++) {
Map<String, Object> map = new HashMap<String, Object>();
a = listA.get(j);
map.put("name", a.getName());
map.put("photo", a.getPhoto());
oList.add(map);
}
listB = root.getB();
oList2 = new ArrayList<Map<String, Object>>();
for (int j = 0; j < listB.size(); j++) {
Map<String, Object> map = new HashMap<String, Object>();
b = listB.get(j);
map.put("name", b.getName());
map.put("photo", b.getPhoto());
oList2.add(map);
}
oList.addAll(oList2);
}
mListView.setAdapter(new MyAdapter(oList, this));
} catch (Exception e) {
e.printStackTrace();
}
}截止目前，這些資料就解析完成了。當然，可能看起來雲裡霧裡，下面貼上所有的程式碼：
佈局檔案：activity_main.xml
<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<ListView
android:id="@+id/listview"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</ListView>
</RelativeLayout>item.xml
<?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="vertical"
android:padding="5dip" >
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="姓名："
android:textSize="20sp" />
<TextView
android:id="@+id/name"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
android:textSize="18sp" />
</LinearLayout>
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="照片："
android:textSize="20sp" />
<TextView
android:id="@+id/photo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=""
android:textSize="18sp" />
</LinearLayout>
</LinearLayout>1.MainActivity.java
public class MainActivity extends Activity {
private String data;
private Gson gson;
private Root root;
private A a;
private B b;
private ListView mListView;
private List<Map<String, Object>> oList;
private List<Map<String, Object>> oList2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mListView = (ListView) findViewById(R.id.listview);
gson = new Gson();
a = new A();
b = new B();
root = new Root();
try {
InputStream is = getResources().getAssets().open("text.txt");
byte[] b = new byte[is.available()];
is.read(b);
data = new String(b);
analysisData(data);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
/*
* 解析資料
*/
public void analysisData(String data) {
try {
// Type listType = new TypeToken<List<Root>>() {
// }.getType();
oList = new ArrayList<Map<String, Object>>();
List<Root> appinfos = new ArrayList<Root>();
Root depts = gson.fromJson(data, Root.class);
appinfos.add(depts);
for (int i = 0; i < appinfos.size(); i++) {
root = appinfos.get(i);
List<A> listA = new ArrayList<A>();
List<B> listB = new ArrayList<B>();
listA = root.getA();
for (int j = 0; j < listA.size(); j++) {
Map<String, Object> map = new HashMap<String, Object>();
a = listA.get(j);
map.put("name", a.getName());
map.put("photo", a.getPhoto());
oList.add(map);
}
listB = root.getB();
oList2 = new ArrayList<Map<String, Object>>();
for (int j = 0; j < listB.size(); j++) {
Map<String, Object> map = new HashMap<String, Object>();
b = listB.get(j);
map.put("name", b.getName());
map.put("photo", b.getPhoto());
oList2.add(map);
}
oList.addAll(oList2);
}
mListView.setAdapter(new MyAdapter(oList, this));
} catch (Exception e) {
e.printStackTrace();
}
}
}實體類的程式碼如下：
A.java
public class A {
private String numid;
private String name;
private String abbreviation;
private String photo;
public void setNumid(String numid) {
this.numid = numid;
}
public String getNumid() {
return this.numid;
}
public void setName(String name) {
this.name = name;
}
public String getName() {
return this.name;
}
public void setAbbreviation(String abbreviation) {
this.abbreviation = abbreviation;
}
public String getAbbreviation() {
return this.abbreviation;
}
public void setPhoto(String photo) {
this.photo = photo;
}
public String getPhoto() {
return this.photo;
}
}B、C、D的跟A一樣，就不再贅述了。
還有一個Roor.java:
public class Root {
private List<A> a;
private List<B> b;
private List<C> c;
private List<D> d;
public void setA(List<A> a) {
this.a = a;
}
public List<A> getA() {
return this.a;
}
public void setB(List<B> b) {
this.b = b;
}
public List<B> getB() {
return this.b;
}
public void setC(List<C> c) {
this.c = c;
}
public List<C> getC() {
return this.c;
}
public void setD(List<D> d) {
this.d = d;
}
public List<D> getD() {
return this.d;
}
}介面卡程式碼：MAdapter.java
public class MyAdapter extends BaseAdapter {
private List<Map<String, Object>> roots;
private Context mContext;
private LayoutInflater inflater;
private Root root;
public MyAdapter(List<Map<String, Object>> roots, Context mContext) {
this.roots = roots;
this.mContext = mContext;
inflater = LayoutInflater.from(mContext);
}
@Override
public int getCount() {
return roots.size();
}
@Override
public Object getItem(int position) {
return roots.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
viewHonder honder = null;
if (convertView == null) {
convertView = inflater.inflate(R.layout.item, null);
honder = new viewHonder();
honder.mName = (TextView) convertView.findViewById(R.id.name);
honder.mPhoto = (TextView) convertView.findViewById(R.id.photo);
convertView.setTag(honder);
} else {
honder = (viewHonder) convertView.getTag();
}
Map<String, Object> map = new HashMap<String, Object>();
map = roots.get(position);
honder.mName.setText(map.get("name") + "");
honder.mPhoto.setText(map.get("photo") + "");
return convertView;
}
class viewHonder {
TextView mName;
TextView mPhoto;
}
}好了。這時候已經可以實現這個功能了。