Android-async-http Open source project processing of return JSON data on the server side

I. Building the environment in the Java EE project

1. Importing related JAR Packages

2. Build the relevant packages and classes

3. Simple implementation of the methods in the class

User:

Declares the following properties, implements the parameterless constructor and the parameter constructor, and the respective get and set methods

Userdao:

Userdaoimpl:

Jsonservlet:

<span style= "White-space:pre" ></span>protected void doget (HttpServletRequest request, HttpServletResponse response) throws Servletexception, IOException {//from database Userdao Daoimpl = new Userdaoimpl (); list<user> entities = Daoimpl.findall ();//Convert the list collection to a JSON data format Jsonarray Jsonarray = Jsonarray.fromobject ( entities); Response.setcontenttype ("Application/json");//Data Response.getwriter () of the response type JSON. Write ( Jsonarray.tostring ()); Response.getwriter (). Close (); protected void DoPost (HttpServletRequest request,httpservletresponse response) throws Servletexception, IOException { Doget (request, response);}

Second, the processing of the server-side return JSON data in the Android project

1. Importing the JAR Package

2. Add Permissions

3. Implementing the Layout file

<!--V-level in MVC mode--    <listview        android:id= "@+id/lv_users"        android:layout_width= "Match_parent"        android:layout_height= "wrap_content"        android:layout_alignparentbottom= "true"/>

The main contents of 4.mainactivity.java are shown in the following detail code:

Package Www.csdn.net.activity;import Java.util.arraylist;import Java.util.list;import org.apache.http.Header; Import Org.json.jsonarray;import org.json.jsonexception;import org.json.jsonobject;import android.app.Activity; Import Android.os.bundle;import Android.widget.arrayadapter;import Android.widget.listview;import Android.widget.toast;import Com.loopj.android.http.asynchttpclient;import Com.loopj.android.http.jsonhttpresponsehandler;public class Mainactivity extends Activity {private ListView lv_users; @Overrideprotected void OnCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate); Setcontentview ( R.layout.activity_main); lv_users = (ListView) Findviewbyid (r.id.lv_users); InitData ()//m layer//initdata itself is processed in a sub-thread} private void InitData () {//Access server-side get JSON data//Create client Object asynchttpclient = new Asynchttpclient (); String url = "Http://172.16.237.227:8080/video/JsonServlet"; Toast.maketext (this, "Send request to Server", Toast.length_long). Show (); Client.get (URL, new Jsonhttpresponsehandler () {// Return Jsonarray Object | Jsonobject object @overridepublic void onsuccess (int statusCode, header[] headers,jsonarray response) {super.onsuccess ( StatusCode, headers, response); if (StatusCode = = 200) {//Storage array variable list<string> objects = new arraylist<> (); for ( int i = 0; I < response.length (); i++) {try {//Get a specific Jsonobject object Jsonobject obj = Response.getjsonobject (i); Objects.add (obj.getstring ("name"));} catch (Jsonexception e) {//TODO auto-generated catch Blocke.printstacktrace ();}} C control layer is mainly for data processing arrayadapter<string> adapter = new Arrayadapter<string> (Mainactivity.this, Android. R.layout.simple_list_item_1, objects);//Set the displayed content Lv_users.setadapter (adapter);//C Vacant}});}}

5. The implementation effect is as follows:

Third, supplementary

1. Jsonobject objects can get property values for a specified property name by getting ("property name"), GetString ("property name"), GetInt ("property name"), and so on.

For example: In this case, you can pass System.out.println ("ordinal:" + obj.getint ("id") + "Name:" + obj.getstring ("name") + "---Password:" + obj.getstring ("Pass ") +"---"+ obj.get (" RegDate ") to verify the results.

2. The cause of the bug may be:

Internet permissions are not added, the server does not start, access to the server path is wrong, the control object is not acquired, the settings displayed should be the Lv_users.setadapter () method instead of the SetText () method, and so on.