Json--Android中数据文件解析（Json解析--从服务器端获取数据并且解析，显示在客户端上面)

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前面学习过了使用SAX解析XML数据(点击进入:SAX解析XML数据),今天学习Json解析；

首先说一下Json数据的最基本的特点，Json数据是一系列的键值对的集合,和XML数据来比，Json数据的体积更加小，传输效率高，易解析，不过可读性不高;

因为这次要从服务器端得到Json数据，并且通过解析之后把解析后的数据显示在Android客户端中，首先部署服务器端代码(直接使用Jsp/Servlet):

构造的Json数据如下:

[{"name":"张三","address":"北京","age":20},{"name":"李四","address":"上海","age":30},{"name":"王五","address":"深圳","age":35}]

[一]服务器端(Person.java省略):

①:数据构造JsonService.java

public class JsonService {
public static List<Person> getListPerson() {
List<Person> mLists = new ArrayList<Person>();
mLists.add(new Person("张三", "北京", 20));
mLists.add(new Person("李四", "上海", 30));
mLists.add(new Person("王五", "深圳", 35));
return mLists;
}

②:Servlet的代码（包括构造Json数据，没有使用Json数据转换方法）JsonServlet.java

public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
response.setCharacterEncoding("UTF-8");
PrintWriter out = response.getWriter();
List<Person> persons = JsonService.getListPerson();
StringBuffer sb = new StringBuffer();
sb.append('[');
for (Person person : persons) {
sb.append('{').append("\"name\":").append("\""+person.getName()+"\"").append(
",");
sb.append("\"address\":").append("\""+person.getAddress()+"\"").append(",");
sb.append("\"age\":").append(person.getAge());
sb.append('}').append(",");
}
sb.deleteCharAt(sb.length() - 1);
sb.append(']');
out.write(new String(sb));
out.flush();
out.close();
}

③:部署到Tomact 浏览器输入http://localhost/JsonWeb/JsonServlet直接访问结果如下:

至此服务器端代码编码完成，下面进行客户端代码编写;

(二)客户端(Person类，和展示数据的布局文件因为简单省去)

①:获取服务器端的Json数据并且解析的工具类JsonParse.java

必要的需要导入的包省去

public class JsonParse {
/**
* 解析Json数据
*
* @param urlPath
* @return mlists
* @throws Exception
*/
public static List<Person> getListPerson(String urlPath) throws Exception {
List<Person> mlists = new ArrayList<Person>();
byte[] data = readParse(urlPath);
JSONArray array = new JSONArray(new String(data));
for (int i = 0; i < array.length(); i++) {
JSONObject item = array.getJSONObject(i);
String name = item.getString("name");
String address = item.getString("address");
int age = item.getInt("age");
mlists.add(new Person(name, address, age));
}
return mlists;
}
/**
* 从指定的url中获取字节数组
*
* @param urlPath
* @return 字节数组
* @throws Exception
*/
public static byte[] readParse(String urlPath) throws Exception {
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] data = new byte[1024];
int len = 0;
URL url = new URL(urlPath);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
InputStream inStream = conn.getInputStream();
while ((len = inStream.read(data)) != -1) {
outStream.write(data, 0, len);
}
inStream.close();
return outStream.toByteArray();
}
}

②:主Activity类

<pre code_snippet_id="216479" snippet_file_name="blog_20140304_5_9107204" name="code" class="java">public class MainActivity extends Activity {
private Button mButton;
private ListView mListView;
//使用IP不能使用localhost或者127.0.0.1，因为android模拟器默认绑定这个IP，这里应该访问局域网IP
private static final String urlPath = "http://10.16.31.207/JsonWeb/JsonServlet";
private static final String TAG = "MainActivity";
private List<Person> persons;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mButton = (Button) findViewById(R.id.button1);
mListView = (ListView) findViewById(R.id.listView1);
mButton.setOnClickListener(new MyOnClickListener());
}
private class MyOnClickListener implements OnClickListener {
@Override
public void onClick(View v) {
try {
// 得到Json解析成功之后数据
persons = JsonParse.getListPerson(urlPath);
List<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
for (int i = 0; i < persons.size(); i++) {
HashMap<String, Object> map = new HashMap<String, Object>();
map.put("name", persons.get(i).getName());
map.put("address", persons.get(i).getAddress());
map.put("age", persons.get(i).getAge());
data.add(map);
}
//初始化适配器，并且绑定数据
SimpleAdapter _Adapter = new SimpleAdapter(MainActivity.this,
data, R.layout.listview_item, new String[] { "name",
"address", "age" }, new int[] { R.id.textView1,
R.id.textView2, R.id.textView3 });
mListView.setAdapter(_Adapter);
} catch (Exception e) {
Toast.makeText(MainActivity.this, "解析失败", 2000).show();
Log.i(TAG, e.toString());
}
}
}</pre>