Java数据解析---JSON

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发布于 2018-05-18 04:50:12

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一、Java数据解析分为：XML解析和JSON解析

XML解析即是对XML文件中的数据解析，而JSON解析即对规定形式的数据解析,比XML解析更加方便

JSON解析基于两种结构：

1、键值对类型

1          {
2             “name”:”Alice”,
3             “age”:19
4          }

2、数组类型（有序列表）

1  {
2         “students”:
3         [
4             {“name”:”Alice”,“age”:19},
5             {“name”:”Ben”,”age”:11}
6         ]
7      }

JSON解析依赖于外部jar包。

首先、服务器端项目要导入json的jar包和json所依赖的jar包至builtPath路径下（这些可以到JSON-lib官网下载：http://json-lib.sourceforge.net/）

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二、JSON解析字符串

1、先看一个最简单的字符串数据

1 String json = "{name:'Alice',age:19,sex:'gril'}";

例如，对于这样一个字符串数据进行JSON解析，要解析的数据即是冒号（:）后面的数据 Alice 19 gril

把{}包含的所有看作是一个对象，把[]包含的看作为一个数组，分清JSONObject 和JSONArray 多练习就掌握了

 1 package demo;
 2 
 3 import org.json.JSONException;
 4 import org.json.JSONObject;
 5 
 6 public class Demo01 {
 7     public static void main(String[] args) throws JSONException {
 8         String json = "{name:'Alice',age:19,sex:'gril'}";
 9         //将{}里面的整体看作一个对象
10         JSONObject obj = new JSONObject(json);
11         //根据键名（:前面的）获得值（：后面的）
12         String name = obj.getString("name");
13         int age = obj.getInt("age");
14         String sex = obj.getString("sex");
15         
16         System.out.println("name:"+name+",age:"+age+",sex:"+sex);
17     }
18 }

2、再看一个对象中含对象的

1         String json = "{student:{name:'Lucy',age:19,sex:'gril'}}";

 1 package demo;
 2 
 3 import org.json.JSONException;
 4 import org.json.JSONObject;
 5 
 6 public class Demo01 {
 7 
 8     public static void main(String[] args) throws JSONException {
 9         String json = "{student:{name:'Lucy',age:19,sex:'gril'}}";
10         JSONObject obj = new JSONObject(json);
11         //注意点
12         JSONObject stu =obj.getJSONObject("student");
13         String name = stu.getString("name");
14         int age = stu.getInt("age");
15         String sex = stu.getString("sex");
16         
17         System.out.println("name:"+name+",age:"+age+",sex:"+sex);
18     }
19 }

3、再看字符串中含有数组类型的情况

1 String json = "{students:[{address:'山东',age:10,name:'小明'},{address:'河南',age:15,name:'小李'}]}";

 1 package json;
 2 
 3 import org.json.JSONArray;
 4 import org.json.JSONException;
 5 import org.json.JSONObject;
 6 
 7 public class Demo03 {
 8     public static void main(String[] args) throws JSONException {
 9         String json = "{students:[{address:'山东',age:10,name:'小明'},{address:'河南',age:15,name:'小李'}]}";
10         JSONObject obj = new JSONObject(json);
11         JSONArray stu = obj.getJSONArray("students");
12         for(int i=0;i<stu.length();i++)
13         {
14             JSONObject s = stu.getJSONObject(i);
15             String name = s.getString("name");
16             int age = s.getInt("age");
17             String address = s.getString("address");
18             
19             System.out.println("第"+i+"个对象"+"name:"+name+",age:"+age+",address:"+address);
20             
21         }
22     }
23 }
24 
25 
26 第0个对象name:小明,age:10,address:山东
27 第1个对象name:小李,age:15,address:河南

4、看几个发杂点的字符串JSON解析

1         String json = "{object:{persons:[{name:'小明',image:'帅'},{name:'小李',image:'高'},{name:'小王',image:'富'}]}}";

 1 package json;
 2 
 3 import org.json.JSONArray;
 4 import org.json.JSONException;
 5 import org.json.JSONObject;
 6 
 7 public class Demo04 {
 8     public static void main(String[] args) throws JSONException {
 9         String json = "{object:{persons:[{name:'小明',image:'帅'},{name:'小李',image:'高'},{name:'小王',image:'富'}]}}";
10         JSONObject obj = new JSONObject(json);
11         JSONObject object = obj.getJSONObject("object");
12 //        JSONObject person = object.getJSONObject("persons");
13         JSONArray p = object.getJSONArray("persons");
14         for(int i=0;i<p.length();i++)
15         {
16             JSONObject person = p.getJSONObject(i);
17             String name = person.getString("name");
18             String image = person.getString("image");
19             System.out.println("第"+(i+1)+"个对象的name:"+name+",image:"+image);
20         }
21     
22     }
23 }
24 
25 
26 第1个对象的name:小明,image:帅
27 第2个对象的name:小李,image:高
28 第3个对象的name:小王,image:富

5、

1         String json = "[{school:'清华',good:'false',class:{name:'物理系',count:100}},{school:'北大',good:'true',class:{name:'化学系',count:45}}]";

 1 package json;
 2 
 3 
 4 
 5 import org.json.JSONArray;
 6 import org.json.JSONException;
 7 import org.json.JSONObject;
 8 
 9 public class Demo05 {
10     public static void main(String[] args) throws JSONException {
11         String json = "[{school:'清华',good:'false',class:{name:'物理系',count:100}},{school:'北大',good:'true',class:{name:'化学系',count:45}}]";
12         JSONArray arr = new JSONArray(json);
13         for(int i=0;i<arr.length();i++)
14         {
15             JSONObject ss = arr.getJSONObject(i);
16             String school = ss.getString("school");
17             String good = ss.getString("good");
18             JSONObject clas = ss.getJSONObject("class");
19             String name = clas.getString("name");
20             String count = clas.getString("count");
21             System.out.println("school:"+school+",good:"+good+",className:"+name+",classCount:"+count);
22         }
23     }
24 }
25 
26 
27 
28 school:清华,good:false,className:物理系,classCount:100
29 school:北大,good:true,className:化学系,classCount:45

6、

1         String json ="{status:2,result:[{name:'小明',id:1}, {name:'小红',id:5},{name:'小王',id:7}]} " ;

 1 package json;
 2 
 3 import javax.naming.spi.DirStateFactory.Result;
 4 
 5 import org.json.JSONArray;
 6 import org.json.JSONException;
 7 import org.json.JSONObject;
 8 
 9 public class Demo06 {
10     public static void main(String[] args) throws JSONException {
11         String json ="{status:2,result:[{name:'小明',id:1}, {name:'小红',id:5},{name:'小王',id:7}]} " ;
12         JSONObject obj = new JSONObject(json);
13         String status = obj.getString("status");
14         JSONArray result = obj.getJSONArray("result");
15         for(int i=0;i<result.length();i++)
16         {
17             JSONObject com = result.getJSONObject(i);
18             String name = com.getString("name");
19             String id = com.getString("id");
20             System.out.println("name:"+name+",id:"+id);
21             
22         }
23         
24         
25         
26     }
27 }
28 
29 
30 
31 name:小明,id:1
32 name:小红,id:5
33 name:小王,id:7

三、解析网络中的数据

步骤：

1、得到指定网络地址上的数据的输入流，并存储到内存流

2、将内存流中的数据转换成字符串

3、对字符串进行JSON解析，并将数据存入到集合中

 1 import java.io.IOException;
 2 import java.util.List;
 3 
 4 import org.json.JSONException;
 5 
 6 public class Test {
 7 
 8     public static void main(String[] args) throws IOException, JSONException {
 9         String path = "http://..."; //数据源
10         
11         //得到json字符串
12         String jsonString = HttpUtil.getJsonString(path);
13         //把json字符串数据解析成集合
14         List<T> list = HttpUtil.jsonParser(jsonString);
15         //遍历集合
16         for(T t:list)
17         {
18             System.out.println(t);
19         }
20 
21     }
22 
23 }

 1 import java.io.ByteArrayOutputStream;
 2 import java.io.IOException;
 3 import java.io.InputStream;
 4 import java.net.HttpURLConnection;
 5 import java.net.MalformedURLException;
 6 import java.net.URL;
 7 import java.util.ArrayList;
 8 import java.util.List;
 9 
10 import org.json.JSONArray;
11 import org.json.JSONException;
12 import org.json.JSONObject;
13 
14 public class HttpUtil {
15     
16     //得到服务器端的json字符串
17     public static String getJsonString(String path) throws IOException
18     {
19         URL url = new URL(path);
20         HttpURLConnection conn = (HttpURLConnection) url.openConnection();
21         
22         conn.setRequestMethod("GET");
23         conn.setConnectTimeout(5000);
24         conn.setDoInput(true);
25         InputStream in = null;
26         if(conn.getResponseCode()==200)
27         {
28             in = conn.getInputStream();
29             return changeToString(in);
30         }
31         return null;
32     }
33 
34     private static String changeToString(InputStream in) throws IOException {
35         ByteArrayOutputStream bos = new ByteArrayOutputStream();
36         byte[] arr = new byte[1024];
37         int len = 0;
38         while((len = in.read(arr))!=-1)
39         {
40                         //写入内存流
41             bos.write(arr,0,len);
42         }
43                 //转换成字符串形式返回
44         return new String(bos.toByteArray(),"utf-8");
45     }
46     
47     //解析json字符串，
48     public static List<T> jsonParser(String jsonString) throws JSONException
49     {
50         List<T> list = new ArrayList<T>();
51         JSONObject obj = new JSONObject(jsonString);
52         //依据实际情况进行JSON解析
53         return list; //多个人的信息
54         
55     }
56  
57 }
58 
59 
60 
61 
62