android使用Thread实现json数据的传递，并且使用ListView显示
浏览数：16 /
时间：2015年06月11日
在android 4.0以后，不能在主线程中使用网路资源。所以对于使用json传递的数据，我们要用它直接生成Listview会报一个android.os.NetworkOnMainThreadException的异常，那么要如何处理这些网络资源呢？实际上有很多种方法来处理这些网络资源，这里介绍一种使用新线程（new Thread(){}）的方式进行处理。
这里我要实现通过接收JSON来生成ListView的操作。
一、建立Web Service
1.启动Java EE，建立一个Dynamic Web Project
选上自动创建xml文件。
2.新建一个Servlet，并在xml文件中配置。
web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>MyServer</display-name>
<servlet>
<display-name>MyServer</display-name>
<servlet-name>MyServer</servlet-name>
<servlet-class>org.zyh.server.xml.MyServer</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MyServer</servlet-name>
<url-pattern>/MyServer</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>3.建立业务Bean，实现业务方法。
MyService.java
package org.zyh.server.service;
import java.util.List;
public interface MyService {
public List<News> getLastNews();
}MyServiceBean.java
package org.zyh.server.impl;
import java.util.ArrayList;
import java.util.List;
import org.zyh.server.entity.News;
import org.zyh.server.service.MyService;
public class MyServerImpl implements MyService {
@Override
public List<News> getLastNews() {
List<News> list = new ArrayList<>();
list.add(new News(22,"二狗子",45));
list.add(new News(23,"三胖子",46));
list.add(new News(24,"狗剩子",47));
return list;
}
}这里就直接写一下虚拟的数据，就不链接数据库了。
4.实体类 Info.java
package org.zyh.server.entity;
public class Info {
Integer id;
String title;
Integer age;
public Info(Integer id, String title, Integer age) {
this.id = id;
this.title = title;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public Integer getTimelenght() {
return age;
}
public void setTimelenght(Integer age) {
this.age = age;
}
}5. MyServlet.java
package org.zyh.server.xml;
import java.io.IOException;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.zyh.server.entity.Info;
import org.zyh.server.impl.MyServerImpl;
import org.zyh.server.service.MyService;
public class MyServlet extends HttpServlet {
/**
*
*/
private static final long serialVersionUID = 1L;
private MyService myService = new MyServerImpl();
public void doGet(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
doPost(request,response);
}
public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException{
List<Info> info = myService.getLastInfo();
StringBuilder json = new StringBuilder();
json.append(‘[‘);
for(Info i : info){
json.append("{");
json.append("id:").append(i.getId()).append(",");
json.append("title:\"").append(i.getTitle()).append("\",");
json.append("age:").append(i.getAge());
json.append("},");
}
json.deleteCharAt(json.length()-1);
json.append(‘]‘);
request.setAttribute("json", json.toString());
request.getRequestDispatcher("/WEB-INF/page/info.jsp").forward(request, response);
}
}6.在WEB-INF下建立page/info.jsp
<%@ page language="java" contentType="text/plain; charset=utf-8"
pageEncoding="utf-8"%>${json}7.将工程run on server
二、在android上读取json数据，并生成listview。
1.建立工程 JSONToListView
布局文件
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
tools:context=".MainActivity" >
<ListView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/listView" />
</LinearLayout>item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal" >
<TextView
android:layout_width="200dp"
android:layout_height="wrap_content"
android:id="@+id/name"
/>
<TextView
android:layout_width="200dp"
android:layout_height="wrap_content"
android:id="@+id/age"
/>
</LinearLayout>Info.java
package org.zyh.jsontolistvew;
public class Info {
Integer id;
String name;
Integer age;
public Info(){};
public Info(Integer id, String name, Integer age) {
this.id = id;
this.name = name;
this.age = age;
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
}MyService.java
package org.zyh.jsontolistvew;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import org.json.JSONArray;
import org.json.JSONObject;
import android.util.Log;
public class InfoService {
public static List<Info> getLastInfo() throws Exception{
String path = "http://10.10.1.81:8080/MyServer/MyServlet";
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setConnectTimeout(5000);
conn.setRequestMethod("GET");
if(conn.getResponseCode() == 200){
InputStream input = conn.getInputStream();
return JSONParse(input);
}
return null;
}
private static List<Info> JSONParse(InputStream input) throws Exception {
List<Info> list = new ArrayList<Info> ();
byte[] data = StreamTool.read(input);
String stringInfo = new String(data);
JSONArray jsonArray = new JSONArray(stringInfo);
for(int i = 0;i<jsonArray.length();i++){
JSONObject jsonObject = jsonArray.getJSONObject(i);
Info info = new Info(jsonObject.getInt("id"),
jsonObject.getString("title"),
jsonObject.getInt("age"));
list.add(info);
}
return list;
}
}StreamTool.java
package org.zyh.jsontolistvew;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
public class StreamTool {
public static byte[] read(InputStream inStream) throws Exception{
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
if((len=inStream.read(buffer))!=1){
outStream.write(buffer,0,len);
}
inStream.close();
return outStream.toByteArray();
}
}MainActivity.java
package org.zyh.jsontolistvew;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.widget.ListView;
import android.widget.SimpleAdapter;
public class MainActivity extends Activity {
protected static final int ADD_ADPATER = 1;
private ListView listView ;
private Handler handler = new Handler(){
public void handleMessage(android.os.Message msg){
if(msg.what == ADD_ADPATER){
SimpleAdapter adpater = (SimpleAdapter) msg.obj;
listView.setAdapter(adpater);
}
}
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) this.findViewById(R.id.listView);
new Thread(){
public void run(){
try{
List<Info> list = InfoService.getLastInfo();
List<HashMap<String,Object>> data = new ArrayList<HashMap<String,Object>>();
for(Info info : list){
HashMap<String,Object> item = new HashMap<String,Object>();
item.put("id", info.getId());
item.put("name", info.getName());
item.put("age", info.getAge());
data.add(item);
}
SimpleAdapter adapter = new SimpleAdapter(MainActivity.this, data, R.layout.item, new String[]{"name","age"}, new int[]{R.id.name,R.id.age});
Message msg = new Message();
msg.what = ADD_ADPATER;
msg.obj = adapter;
handler.sendMessage(msg);
}catch(Exception e){
e.getStackTrace();
}
}
}.start();
}
}最后别忘了在AnaroidManifest.xml中加入Internet权限<uses-permission andriod:name="android.permission.INTERNET">
效果如如下
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