Android系列之获取服务端json数据

末蓝、 2021-09-10 13:34 383阅读 0赞

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**Android从服务端获取json解析显示在客户端上面**

百度经验:jingyan.baidu.com

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:

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

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

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());

至此服务器端和客户端编码介绍，运行android应用结果截图:

Android系列之获取服务端json数据

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