• 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

    版权声明:原创作品,谢绝转载!否则将追究法律责任。

      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  */

    ” 

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  • 原文地址:https://www.cnblogs.com/yinzhengjie/p/9326978.html
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