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)
2023-09-14 08:59:52 时间
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
- <span style="font-size: 16px; ">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;
- }</span>
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
- <span style="font-size: 16px; ">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();
- }</span>
- <span style="font-size: 16px; ">
- </span>
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
- <span style="font-size:18px;">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();
- }
- }</span>
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><br>
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