Java基础-处理json字符串解析案例

　　　　　　　　　　　　　　　　Java基础-处理json字符串解析案例

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正杰

　　作为一名开发人员，想必大家或多或少都有接触到XML文件，XML全称为“extensible markup language”，即可扩展性标记语言。它由于可读性很好，但是在网络传输上，这种数据格式往往很占用带宽等诸多缺点，因此就诞生了Json，它比XML数据更小、更快、更容易解析。数据由名称-值对表示，由逗号分隔开，花括号保存对象，方括号保存数组。Json值可以是：数字/字符串/逻辑值/数组/对象/null。

　　接下来我们就一起看看如何创建一个json文件以及如何解析json文件。

一.java自定义对象对象和json字符串的互转

1>.添加Maven依赖（添加最后一个依赖json即可）

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 <project xmlns="http://maven.apache.org/POM/4.0.0"
 3          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 4          xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 5     <modelVersion>4.0.0</modelVersion>
 6 
 7     <groupId>groupId</groupId>
 8     <artifactId>MyHadoop</artifactId>
 9     <version>1.0-SNAPSHOT</version>
10 
11     <dependencies>
12         <dependency>
13             <groupId>org.apache.hadoop</groupId>
14             <artifactId>hadoop-client</artifactId>
15             <version>2.7.3</version>
16         </dependency>
17 
18         <!-- https://mvnrepository.com/artifact/junit/junit -->
19         <dependency>
20             <groupId>junit</groupId>
21             <artifactId>junit</artifactId>
22             <version>4.12</version>
23             <scope>test</scope>
24         </dependency>
25 
26         <dependency>
27             <groupId>mysql</groupId>
28             <artifactId>mysql-connector-java</artifactId>
29             <version>5.1.17</version>
30         </dependency>
31         <dependency>
32             <groupId>com.alibaba</groupId>
33             <artifactId>fastjson</artifactId>
34             <version>1.2.47</version>
35         </dependency>
36 
37     </dependencies>
38     
39 </project>

2>.具体实现代码如下：

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.json;
 7 
 8 public class Teacher {
 9     private String name;
10     private int age;
11 
12     public Teacher(String name, int age) {
13         this.name = name;
14         this.age = age;
15     }
16 
17     public Teacher() {
18     }
19 
20     public String getName() {
21         return name;
22     }
23 
24     public void setName(String name) {
25         this.name = name;
26     }
27 
28     public int getAge() {
29         return age;
30     }
31 
32     public void setAge(int age) {
33         this.age = age;
34     }
35 
36     public String toString() {
37         return "Teacher{" + "name='" + name  + ", age=" + age + '}';
38     }
39 }

Teacher.java 文件内容

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.json;
 7 
 8 import com.alibaba.fastjson.JSONObject;
 9 
10 import java.io.FileInputStream;
11 import java.io.FileOutputStream;
12 import java.io.IOException;
13 
14 public class JsonOperation {
15     public static final String filePath =  "D:\10.Java\IDE\yhinzhengjieData\MyHadoop\JSON\teacher.txt";
16 
17     public static void main(String[] args) throws Exception {
18         generatingJSON();
19         System.out.println("=============我是分割线=============");
20         parsingJSON();
21     }
22     //生成json文本
23     private static void generatingJSON() throws IOException {
24         Teacher yzj = new Teacher("尹正杰", 18);
25         String json = JSONObject.toJSONString(yzj);
26         System.out.println(json);
27         FileOutputStream fos = new FileOutputStream(filePath);
28         byte[] buf = new byte[1024];
29         fos.write(json.getBytes());
30         fos.close();
31     }
32 
33     //解析json文本
34     private static void parsingJSON() throws IOException {
35         byte[] buf = new byte[1024];
36         FileInputStream fis = new FileInputStream(filePath);
37         //由于我的文件较小，为了实验方便我就一次性读取出来了
38         JSONObject json = JSONObject.parseObject( new String(buf,0,fis.read(buf)));
39         System.out.println(json);
40     }
41 }
42 
43 
44 
45 
46 /*
47 以上代码执行结果如下:
48 {"age":18,"name":"尹正杰"}
49 =============我是分割线=============
50 {"name":"尹正杰","age":18}
51  */

二.Java数据类型和Json互相转换案例

以下是list和json字符串的互转，当然，map的转换json和其方法类似，我这里就不多举例了：

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.json;
 7 
 8 public class Teacher {
 9     private String name;
10     private int age;
11 
12     public Teacher(String name, int age) {
13         this.name = name;
14         this.age = age;
15     }
16 
17     public Teacher() {
18     }
19 
20     public String getName() {
21         return name;
22     }
23 
24     public void setName(String name) {
25         this.name = name;
26     }
27 
28     public int getAge() {
29         return age;
30     }
31 
32     public void setAge(int age) {
33         this.age = age;
34     }
35 
36     public String toString() {
37         return "Teacher{" + "name='" + name  + ", age=" + age + '}';
38     }
39 }

Teacher.java 文件内容

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.json;
 7 
 8 import com.alibaba.fastjson.JSON;
 9 import com.alibaba.fastjson.JSONArray;
10 import com.alibaba.fastjson.JSONObject;
11 
12 import java.util.ArrayList;
13 import java.util.List;
14 
15 public class JsonOperation {
16     17 
18     public static void main(String[] args) throws Exception {
19         listToJSON();
20         System.out.println("=============我是分割线=============");
21         jsonToList();
22     }
23     public static void listToJSON(){
24         Teacher yzj = new Teacher("尹正杰",18);
25         Teacher yzj1 = new Teacher("yinzhengjie",19);
26         Teacher yzj2 = new Teacher("YINZHENGJIE",20);
27         List<Teacher> lists=new ArrayList<Teacher>();
28         lists.add(yzj);
29         lists.add(yzj1);
30         lists.add(yzj2);
31         String listArray=JSONArray.toJSONString(lists);
32         System.out.println("arrayList:"+listArray);
33     }
34 
35     public static void jsonToList(){
36         String str ="{"names":["尹正杰","yinzhengjie"]}";
37         JSONObject jo = JSON.parseObject(str);
38         JSONArray jsonArray = jo.getJSONArray("names");
39         for (Object o : jsonArray) {
40             System.out.println(o.toString());
41         }
42     }
43 }
44 
45 /*
46 以上代码执行结果如下:
47 arrayList:[{"age":18,"name":"尹正杰"},{"age":19,"name":"yinzhengjie"},{"age":20,"name":"YINZHENGJIE"}]
48 =============我是分割线=============
49 尹正杰
50 yinzhengjie
51  */

三.小试牛刀

　　是不是觉得json处理其实蛮简单的，不是吗？接下来我们来练习以下，解析以下的字符串：需要解析商家评论数据：

{"reviewPics":null,"extInfoList":[{"title":"contentTags","values":["环境优雅","性价比高","干净卫生","停车方便","音响效果好"],"desc":"","defineType":0},{"title":"tagIds","values":["24","300","852","506","173"],"desc":"","defineType":0}],"expenseList":null,"reviewIndexes":[2],"scoreList":null}

 1 /*
 2 @author :yinzhengjie
 3 Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
 4 EMAIL:y1053419035@qq.com
 5 */
 6 package cn.org.yinzhengjie.json;
 7 
 8 import com.alibaba.fastjson.JSON;
 9 import com.alibaba.fastjson.JSONArray;
10 import com.alibaba.fastjson.JSONObject;
11 
12 import java.util.ArrayList;
13 import java.util.List;
14 
15 public class JsonOperation {
16    17 
18     public static void main(String[] args) throws Exception {
19         String comment = "{"reviewPics":null,"extInfoList":[{"title":"contentTags","values":["环境优雅","性价比高","干净卫生","停车方便","音响效果好"],"desc":"","defineType":0},{"title":"tagIds","values":["24","300","852","506","173"],"desc":"","defineType":0}],"expenseList":null,"reviewIndexes":[2],"scoreList":null}";
20         List<String> taggen = taggen(comment);
21         for (String s : taggen) {
22             System.out.println(s);
23         }
24 
25     }
26     /**
27      * 解析商家评论数据
28      */
29     public static List<String> taggen(String comment){
30         JSONObject jo = JSON.parseObject(comment);
31         JSONArray jArray = jo.getJSONArray("extInfoList");
32         if(jArray != null && jArray.size() != 0){
33             List<String> list = new ArrayList<String>();
34             //通过jArray得到第一个json串，作为json对象
35             JSONObject jo2 = jArray.getJSONObject(0);
36             JSONArray jArray2 = jo2.getJSONArray("values");
37             if(jArray2 != null && jArray2.size() != 0){
38                 for (Object o : jArray2) {
39                     //System.out.println(o.toString());
40                     list.add(o.toString());
41                 }
42                 return list;
43             }
44         }
45         return null;
46     }
47 }
48 
49 /*
50 以上代码执行结果如下:
51 环境优雅
52 性价比高
53 干净卫生
54 停车方便
55 音响效果好
56  */

”