android 之json对象解析并展示(含json解析源码)
具体处理思路以及使用到的知识点:
1.使用android的异步处理
2.将要使用的功能(方法)进行封装,以便主类进行调用
3.前台展示要使用适配器模型(这里使用简单适配器(SimpleAdapter))
主类的代码：
package com.example.lenovo.asynctask_json;
import android.graphics.Bitmap;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import com.example.lenovo.asynctask_json.domin.NetUtils;
import java.io.InputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.util.List;
import java.util.Map;
/**
* {}代表 json对象
* []:代表时json 数组
*
* {key:value,key:value,key:value.....}
*
* {
* name:"张三",
*
* age:20,
*
* tel:[111,222,333,444],
*
* loves:[
* {ball:"球"},
* {game:"游戏"}
*
* ]
*
* }
*/
public class MainActivity extends AppCompatActivity {
private ListView listView_movie;
private SimpleAdapter adapter;
private List> list;
//private String path="http://lib.wap.zol.com.cn/ipj/docList.php?class_id=0&page=1&vs=and380&retina=1
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.listView_movie= (ListView) this.findViewById(R.id.listView_movie);
String path= null;
try {
//URLEncoder.encode("热门","utf-8"):将汉字进行Unicode编码
path = "https://movie.douban.com/j/search_subjects?type=movie&tag="+ URLEncoder.encode("热门","utf-8")+"&sort=recommend&page_limit=20&page_start=21";
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
new NetDownLoadAsyncTask().execute(path);
}
private final class NetDownLoadAsyncTask extends AsyncTask>>{
@Override
protected List> doInBackground(String... params) {
//调用NetUtils类的方法,将网址对应的数据以InputStream的形式返回.
InputStream inputStream=NetUtils.getInputStreamByPath(params[0]);
if(inputStream!=null){
//调用NetUtils类的方法,将输入流转换成字符串.
String json=NetUtils.getStringByInputStream(inputStream);
System.out.println("json="+json);
if(json!=null){
//调用NetUtils类的方法,对json对象进行处理
list= NetUtils.getListMapByJsonString(json);
return list;
}
}
return null;
}
@Override
protected void onPostExecute(List> maps) {
if(maps!=null){
System.out.println("maps="+maps);
adapter=new SimpleAdapter(
MainActivity.this,//上下文对象
maps,//数据源
R.layout.movie_item,//前台要展示的，这里是(自己定义到格式)对应点击条目的样式
new String[]{"title","cover"},//键值"title"与"cover"
new int[]{R.id.textView_title,R.id.imageView_cover}//控件对应id的int型数组
){
/**
* 当每绘制一条条目对象时自动调用的方法
* @param position
* @param convertView
* @param parent
* @return
*/
@Override
public View getView(int position, View convertView, ViewGroup parent) {
//System.out.println("===getView(int position="+position+", View convertView="+convertView+", ViewGroup parent="+parent+")===");
//得到当前绘制的条目对象
View view=super.getView(position, convertView, parent);
//System.out.println("view="+view);
ImageView imageView_cover= (ImageView) view.findViewById(R.id.imageView_cover);
Map map=list.get(position);
Bitmap bitmap= (Bitmap) map.get("cover");
//手工设置imageView对应的bitmap对象
imageView_cover.setImageBitmap(bitmap);
return view;
}
};
listView_movie.setAdapter(adapter);
System.out.println("=======");
}else {
System.out.println("从网络上获取数据失败!");
}
}
}
}
封装好的代码：
package com.example.lenovo.asynctask_json.domin;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Created by hsjwcf on 2018/5/29.
*/
public class NetUtils {
/**
* 将给你的网址对应的数据以InputStream的形式返回
* @param path
* @return
*/
public static InputStream getInputStreamByPath(String path){
try {
URL url=new URL(path);
HttpURLConnection httpURLConnection= (HttpURLConnection) url.openConnection();
httpURLConnection.setConnectTimeout(3000);
/*
httpURLConnection.getResponseCode()干了两件事:
A:根据指定的网址向服务器发送请求并得到服务器的回应
B:在回应中包含状态码:200表示访问成功
*/
int responseCode=httpURLConnection.getResponseCode();
if(responseCode==200){//说明本次访问成功
//以输入流的形式得到服务器返回的数据
InputStream inputStream=httpURLConnection.getInputStream();
return inputStream;
}
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
/**
* 根据输入流得到字节数组
* @param inputStream
* @return
*/
public static byte[] getBytesByInputStream(InputStream inputStream){
ByteArrayOutputStream byteArrayOutputStream=new ByteArrayOutputStream();
byte[] buffer=new byte[1024];
int len=0;
try {
while ((len=inputStream.read(buffer))!=-1){
byteArrayOutputStream.write(buffer,0,len);
}
return byteArrayOutputStream.toByteArray();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 根据输入流得到字符串
* @param inputStream
* @return
*/
public static String getStringByInputStream(InputStream inputStream){
ByteArrayOutputStream byteArrayOutputStream=new ByteArrayOutputStream();
byte[] buffer=new byte[1024];
int len=0;
try {
while ((len=inputStream.read(buffer))!=-1){
byteArrayOutputStream.write(buffer,0,len);
}
return byteArrayOutputStream.toString();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
/**
* 通过解析json 字符串得到List>类型的对象
*
*
* {
"subjects": [
{
"rate": "8.3",
"cover_x": 3578,
"title": "暴裂无声",
"url": "https://movie.douban.com/subject/26647117/",
"playable": true,
"cover": "https://img3.doubanio.com/view/photo/s_ratio_poster/public/p2517333671.jpg",
"id": "26647117",
"cover_y": 5078,
"is_new": false
},
{
"rate": "7.0",
"cover_x": 1500,
"title": "负重前行",
"url": "https://movie.douban.com/subject/26793157/",
"playable": false,
"cover": "https://img1.doubanio.com/view/photo/s_ratio_poster/public/p2518648419.jpg",
"id": "26793157",
"cover_y": 2222,
"is_new": false
}
]
}
* @param json
* @return
*/
public static List> getListMapByJsonString(String json){
List> list=new ArrayList<>();
try {
//1.将json 字符串转换成Json对象
JSONObject jsonObject=new JSONObject(json);
//2.根据键得到json 数组
JSONArray jsonArray=jsonObject.getJSONArray("subjects");
//得到数组中元素的个数
int len=jsonArray.length();
for(int i=0;i map=new HashMap<>();
jsonObject= jsonArray.getJSONObject(i);
String title=jsonObject.getString("title");
String cover=jsonObject.getString("cover");
System.out.println("cover="+cover);
//String cover=jsonArray.getString(0);
map.put("title",title);
//将数据源中cover 对应的网址转换成Bitmap 对象
InputStream inputStream=getInputStreamByPath(cover);
byte[] data=getBytesByInputStream(inputStream);
Bitmap bitmap=BitmapFactory.decodeByteArray(data,0,data.length);
map.put("cover",bitmap);
list.add(map);
}
} catch (JSONException e) {
e.printStackTrace();
}
return list;
}
}
前台展示：
<1>
<2>