Android 从网络获取json格式的视频资讯

服务器采用json数据格式返回数据给客户端比xml数据格式性能更好；

json格式：

[{id:7,title:"xxxx",timelength:80},{},{}]

[{id:78,title:"喜羊羊与灰太狼全集",timelength:90},{id:78,title:"实拍舰载直升东海救援演习",timelength:20},{id:78,title:"喀

麦隆VS荷兰",timelength:30}]

http://192.168.1.100:8080/videowebjson/video/list.do?format=json

formbean接收请求参数；format

将json字符串解析为对象；

JSONArray array = new JSONArray(json);

for(int i=0 ; i < array.length() ; i++){

JSONObject item = array.getJSONObject(i); //得到json对象

int id = item.getInt("id");

String title = item.getString("title");

int timelength = item.getInt("timelength");

videos.add(new Video(id, title, timelength));

}

解析json的性能比解析xml的性能高很多！

下面是服务器端代码，采用struts1：

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> 
<servlet>
<servlet-name>struts</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>struts</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

struts-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts-config PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 1.3//EN"
"http://struts.apache.org/dtds/struts-config_1_3.dtd">
<struts-config>
<form-beans >
<form-bean name="videoForm" type="cn.itcast.formbean.VideoForm"></form-bean>
</form-beans>
<action-mappings>
<action path="/video/list" name="videoForm" scope="request" type="cn.itcast.action.VideoListAction">
<forward name="video" path="/WEB-INF/page/videos.jsp"/>
<forward name="jsonvideo" path="/WEB-INF/page/jsonvideos.jsp"/>
</action>

</action-mappings>
</struts-config>

jsonvideo.jsp

<%@ page language="java" contentType="text/plain; charset=UTF-8" pageEncoding="UTF-8"%>${json}

StreamTool.java

package cn.itcast.utils;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;

public class StreamTool {

/**
* 从输入流中获取数据
* @param inStream 输入流
* @return
* @throws Exception
*/
public static byte[] readInputStream(InputStream inStream) throws Exception{
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while( (len=inStream.read(buffer)) != -1 ){
outStream.write(buffer, 0, len);
}
inStream.close();
return outStream.toByteArray();
}
}

Video.java

package cn.itcast.domain;

public class Video {
private Integer id;
private String title;
private Integer time;

public Video(){}

public Video(Integer id, String title, Integer time) {
this.id = id;
this.title = title;
this.time = time;
}
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 getTime() {
return time;
}
public void setTime(Integer time) {
this.time = time;
}

}

VideoService.java

package cn.itcast.service;

import java.util.List;

import cn.itcast.domain.Video;

public interface VideoService {

/**
* 返回最新的视频资讯
* @return
* @throws Exception
*/
public List<Video> getLastVideos() throws Exception;

}

VideoServiceBean.java

package cn.itcast.service.impl;

import java.util.ArrayList;
import java.util.List;
import cn.itcast.domain.Video;
import cn.itcast.service.VideoService;

public class VideoServiceBean implements VideoService {

public List<Video> getLastVideos() throws Exception{
//查询数据库
List<Video> videos = new ArrayList<Video>();
videos.add(new Video(78, "喜羊羊与灰太狼全集", 90));
videos.add(new Video(78, "实拍舰载直升东海救援演习", 20));
videos.add(new Video(78, "喀麦隆VS荷兰", 30));
return videos;
}
}

VideoForm.java

package cn.itcast.formbean;

import org.apache.struts.action.ActionForm;
import org.apache.struts.upload.FormFile;

public class VideoForm extends ActionForm {
private String format;

public String getFormat() {
return format;
}

public void setFormat(String format) {
this.format = format;
}

}

VideoListAction.java

package cn.itcast.action;

import java.util.List;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

import cn.itcast.domain.Video;
import cn.itcast.formbean.VideoForm;
import cn.itcast.service.VideoService;
import cn.itcast.service.impl.VideoServiceBean;

public class VideoListAction extends Action {
private VideoService service = new VideoServiceBean();

public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
//list.do?format=json
List<Video> videos = service.getLastVideos();
VideoForm formbean = (VideoForm)form;
if("json".equals(formbean.getFormat())){
StringBuilder json = new StringBuilder();
json.append('[');	//[{id:7,title:"xxxx",timelength:80},{},{}]
for(Video video : videos){ // {id:76,title:"xxxx",timelength:80}
json.append('{');
json.append("id:").append(video.getId()).append(',');
json.append("title:\"").append(video.getTitle()).append("\",");
json.append("timelength:").append(video.getTime());
json.append('}').append(',');
}
json.deleteCharAt(json.length()-1);
json.append(']');
request.setAttribute("json", json.toString());
return mapping.findForward("jsonvideo");
}else{
request.setAttribute("videos", videos);
return mapping.findForward("video");
}
}

}

下面是Android获取json格式数据代码：

layout/main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<ListView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/listView"
/>
</LinearLayout>

layout/item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content">

<TextView
android:layout_width="250dip"
android:layout_height="wrap_content"
android:id="@+id/title"
/>

<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:id="@+id/timelength"
/>
</LinearLayout>

values/strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="hello">Hello World, MainActivity!</string>
<string name="app_name">视频客户端</string>
</resources>

StreamTool.java

package cn.itcast.utils;

import java.io.ByteArrayOutputStream;
import java.io.InputStream;

public class StreamTool {

/**
* 从输入流中获取数据
* @param inStream 输入流
* @return
* @throws Exception
*/
public static byte[] readInputStream(InputStream inStream) throws Exception{
ByteArrayOutputStream outStream = new ByteArrayOutputStream();
byte[] buffer = new byte[1024];
int len = 0;
while( (len=inStream.read(buffer)) != -1 ){
outStream.write(buffer, 0, len);
}
inStream.close();
return outStream.toByteArray();
}
}

Video.java

package cn.itcast.domain;

public class Video {
private Integer id;
private String title;
private Integer time;

public Video(){}

public Video(Integer id, String title, Integer time) {
this.id = id;
this.title = title;
this.time = time;
}
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 getTime() {
return time;
}
public void setTime(Integer time) {
this.time = time;
}

}

VideoService.java ----------------服务层代码

package cn.itcast.service;

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 org.xmlpull.v1.XmlPullParser;

import android.util.Xml;

import cn.itcast.domain.Video;
import cn.itcast.utils.StreamTool;

public class VideoService {
/**
* 获取最新的视频资讯
* @return
* @throws Exception
*/
public static List<Video> getLastVideos() throws Exception{
String path = "http://192.168.1.100:8080/videoweb/video/list.do";
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setReadTimeout(5*1000);
conn.setRequestMethod("GET");
InputStream inStream = conn.getInputStream();
return parseXML(inStream);
}

public static List<Video> getJSONLastVideos() throws Exception{
List<Video> videos = new ArrayList<Video>();
String path = "http://192.168.1.100:8080/videoweb/video/list.do?format=json";
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection)url.openConnection();
conn.setReadTimeout(5*1000);
conn.setRequestMethod("GET");
InputStream inStream = conn.getInputStream();
byte[] data = StreamTool.readInputStream(inStream);
String json = new String(data);
JSONArray array = new JSONArray(json);
for(int i=0 ; i < array.length() ; i++){
JSONObject item = array.getJSONObject(i);
int id = item.getInt("id");
String title = item.getString("title");
int timelength = item.getInt("timelength");
videos.add(new Video(id, title, timelength));
}
return videos;
}
/**
* 解析服务器返回的协议，得到视频资讯
* @param inStream
* @return
* @throws Exception
*/
private static List<Video> parseXML(InputStream inStream) throws Exception{
List<Video> videos = null;
Video video = null;
XmlPullParser parser = Xml.newPullParser();
parser.setInput(inStream, "UTF-8");
int eventType = parser.getEventType();//产生第一个事件
while(eventType!=XmlPullParser.END_DOCUMENT){//只要不是文档结束事件
switch (eventType) {
case XmlPullParser.START_DOCUMENT:
videos = new ArrayList<Video>();
break;

case XmlPullParser.START_TAG:
String name = parser.getName();//获取解析器当前指向的元素的名称
if("video".equals(name)){
video = new Video();
video.setId(new Integer(parser.getAttributeValue(0)));
}
if(video!=null){
if("title".equals(name)){
video.setTitle(parser.nextText());//获取解析器当前指向元素的下一个文本节点的值
}
if("timelength".equals(name)){
video.setTime(new Integer(parser.nextText()));
}
}
break;

case XmlPullParser.END_TAG:
if("video".equals(parser.getName())){
videos.add(video);
video = null;
}
break;
}
eventType = parser.next();
}
return videos;
}
}

MainActivity.java

package cn.itcast.videoclient;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import cn.itcast.domain.Video;
import cn.itcast.service.VideoService;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.Toast;

public class MainActivity extends Activity {
private ListView listView;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

listView = (ListView)this.findViewById(R.id.listView);
try {
List<Video> videos = VideoService.getJSONLastVideos();

//			List<Video> videos = VideoService.getLastVideos();

List<HashMap<String, Object>> data = new ArrayList<HashMap<String,Object>>();
for(Video video : videos){
HashMap<String, Object> item = new HashMap<String, Object>();
item.put("id", video.getId());
item.put("title", video.getTitle());
item.put("timelength", "时长:"+ video.getTime());
data.add(item);
}
SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.item,
new String[]{"title", "timelength"}, new int[]{R.id.title, R.id.timelength});
listView.setAdapter(adapter);
} catch (Exception e) {
Toast.makeText(MainActivity.this, "获取最新视频资讯失败", 1).show();
Log.e("MainActivity", e.toString());
}
}
}

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cn.itcast.videoclient"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk android:minSdkVersion="8" />

<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<!-- 访问网络的权限 -->
<uses-permission android:name="android.permission.INTERNET"/>

</manifest>