Java Learning Summary (essay)--using JSON parsing to achieve network download

Using JSON for network download
1. Download the JSON string:
(1) Encapsulate URLs into URLs: url url=new url ("url");
(2) using the URL to open http:httpurlconnection conn= (httpurlconnection) ulr.openconnection ();
(3) Start connection: Conn.connect ();
(4) using the input stream to read the network data;
(5) Convert the downloaded data into a byte array;
2. Download the required resources: the same as the above steps, finally using the output stream, write to the destination address
Example 1 (we take the download image as an example (detailed instructions in the note)):
(1) First introduce JAR package
(2) Let's look at the target JSON we're going to download first.
Destination JSON address:
Http://open.qyer.com/qyer/recommands/index?client_id=qyer_android&client_secret=9fcaae8aefc4f9ac4915&v =1&track_deviceid=860806022766611&track_app_version=5.1.1&track_app_channel=360m&track_device_ info=mx2&track_os=android4.2.1&track_user_id=&app_installtime=1404882938883%20http/1.1
Using the online JSON check format allows us to see the composition of the JSON string
(3) Write code:
Download Tool Class (contains two methods for downloading JSON strings and pictures):

Package Org.download.photo;import Java.io.bytearrayoutputstream;import Java.io.fileoutputstream;import Java.io.ioexception;import Java.io.inputstream;import Java.io.outputstream;import java.net.HttpURLConnection;        Import Java.net.url;public class Downloadutil {///JSON string download public static string Downloadjson (string path) {        URL url = null;        InputStream input = null;        HttpURLConnection conn = null;        byte date[] = null; try {url = new URL (path);//1. Encapsulate URLs into URLs conn = (httpurlconnection) url.openconnection ();//2. Turn on HTT P Connect conn.connect ();//3. Start Connection input = Conn.getinputstream ();//4. Gets the network input stream for reading the content to download Bytearr            Ayoutputstream BOS = new Bytearrayoutputstream ();//5. Get byte conversion stream byte[] B = new byte[1024];            int len = 0;            while (len = Input.read (b))! =-1) {bos.write (b, 0, Len);        } date = Bos.tobytearray ();          } catch (Exception e) {  E.printstacktrace ();            } finally {try {input.close ();            } catch (IOException e) {e.printstacktrace ();    }} return new String (date);        }//Download picture public static void Downloadphoto (String photo,string dest) {URL url = null;        InputStream input = null;        HttpURLConnection conn = null;        OutputStream Out=null;        byte date[] = null;            try {out=new fileoutputstream (dest); url = new URL (photo);//1. Encapsulate URLs into URLs conn = (httpurlconnection) url.openconnection ();//2. Open HTTP connection C Onn.connect ();//3. Start Connection input = Conn.getinputstream ();//4. Gets the network input stream for reading the content to download Bytearrayoutputstream b            OS = new Bytearrayoutputstream ();//5. Get byte conversion stream byte[] B = new byte[1024];            int len = 0;            while (len = Input.read (b))! =-1) {bos.write (b, 0, Len); } date = Bos.tobytearray ();            Out.write (date); System.out.println (dest+ "Picture download succeeded to write to local disk:");}        catch (Exception e) {e.printstacktrace ();                } finally {try {input.close ();            Out.close ();            } catch (IOException e) {e.printstacktrace (); }        }    }}

Download Test Class (Main method):

Package Org.download.photo;import Java.io.file;import Org.json.jsonarray;import org.json.jsonexception;import Org.json.jsonobject;public class Downloadtest {public static void main (string[] args) {//1. Download the JSON string S Tring Path = "http://open.qyer.com/qyer/recommands/index?client_id=qyer_android&client_secret= 9fcaae8aefc4f9ac4915&v=1&track_deviceid=860806022766611&track_app_version=5.1.1&track_app_ Channel=360m&track_device_info=mx2&track_os=android4.2.1&track_user_id=&app_installtime=        1404882938883%20http/1.1 ";        String jsonstr = Downloadutil.downloadjson (path); System.out.println (JSONSTR);//test whether the JSON string was successfully downloaded//2. Parse the JSON string to get the photo data (used here for official parsing) try {//3.            JSON string converted to Java object jsonobject jsonobj = new Jsonobject (JSONSTR);  4. Obtain value values Jsonobject Jsondata = jsonobj.optjsonobject ("Data") based on the key value;//Get the data object (first-level directory) Jsonarray Jsonplace = Jsondata.optjsonarray ("PlacE ");//Get the array form of place (Level two directory)//array form jsonplace, get photo data for (int i = 0; i < jsonplace.length (); i+ +) {Jsonobject Jsonob = Jsonplace.optjsonobject (i);//Gets the individual objects in the array String photostr = JSONOB.O                Ptstring ("photo");//Gets the photo string string[] Picarray = Photostr.split ("/"); 5. Start to download the picture and name it Downloadutil.downloadphoto (Photostr, "e:" + File.separator + "Myph            Oto "+file.separator+ picarray[picarray.length-1]);        }} catch (Jsonexception e) {e.printstacktrace (); }    }}

(4) Operation result:

Example 2 (download network pictures, without JSON parsing, set up a download interface, callback interface):
(1) Write code:
Download interface:

package org.download.nettu;//回调接口public interface Load {    void load(byte[] b);}

Download Method Class:

Package Org.download.nettu;import Java.io.bytearrayoutputstream;import Java.io.ioexception;import  Java.io.inputstream;import Java.net.httpurlconnection;import Java.net.url;public class DownloadUtilPic {//Picture public        static void Downloadphoto (String path,load Load) {//1. URL is encapsulated in URL url=null;        InputStream Input=null;        HttpURLConnection Conn=null;             try {url=new URL (path); Conn= (HttpURLConnection) url.openconnection (); Get Network Connection object Conn.connect ();//Turn on network connection Input=conn.getinputstream ();//Get network input stream bytearrayoutputs            Tream bos=new Bytearrayoutputstream ();            int len=0;            Byte[] B=new byte[1024];            while ((Len=input.read (b))!=-1) {bos.write (b, 0, Len);            }//Convert the downloaded data into a byte array byte[] date= bos.tobytearray (); Load.load (date);        Callback Load Method} catch (Exception e) {e.printstacktrace (); }finally{try {                Input.close ();            } catch (IOException e) {e.printstacktrace (); }        }    }}

Test Download Class (Main method):

Package Org.download.nettu;import Java.io.bufferedoutputstream;import Java.io.file;import Java.io.FileOutputStream Import Java.io.ioexception;import Java.io.outputstream;public class Downloadtest {public static void main (string[] Ar        GS) {String path= "http://static.qyer.com/upload/mobile/operation/6e/e1/6ee105f770fe63f625422912b1465e2e.jpg"; Call the Download method Downloadutilpic.downloadphoto (path, new Load () {@Override public void Load (byte                [] b) {OutputStream out=null;                    try {out=new FileOutputStream ("F:" +file.separator+ "abcdgdh.jpg");                    Bufferedoutputstream bos=new Bufferedoutputstream (out);                    Bos.write (b); System.out.println ("Picture downloaded successfully.                ");                } catch (Exception e) {e.printstacktrace ();                    }finally{try {out.close ();      } catch (IOException e) {                  E.printstacktrace ();    }                }            }        }); }}

Operation Result:

Java Learning Summary (essay)--using JSON parsing to achieve network download