Java基礎-處理json字符串解析案例

　　　　　　　　　　　　　　　　Java基礎-處理json字符串解析案例

　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　作者：尹正傑

版權聲明：原創作品，謝絕轉載！否則將追究法律責任。

 

 

 

　　作為一名開發人員，想必大家或多或少都有接觸到XML文件，XML全稱為“extensible markup language”，即可擴展性標記語言。它由於可讀性很好，但是在網絡傳輸上，這種數據格式往往很占用帶寬等諸多缺點，因此就誕生了Json，它比XML數據更小、更快、更容易解析。數據由名稱-值 對表示，由逗號分隔開，花括號保存對象，方括號保存數組。Json值可以是：數字/字符串/邏輯值/數組/對象/null。

　　接下來我們就一起看看如何創建一個json文件以及如何解析json文件。

 

一.java自定義對象對象和json字符串的互轉

1>.添加Maven依賴（添加最后一個依賴json即可）

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>groupId</groupId>
    <artifactId>MyHadoop</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>org.apache.hadoop</groupId>
            <artifactId>hadoop-client</artifactId>
            <version>2.7.3</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/junit/junit -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.17</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>

    </dependencies>
    
</project>

2>.具體實現代碼如下：

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:[e-mail]
*/
package cn.org.yinzhengjie.json;

public class Teacher {
    private String name;
    private int age;

    public Teacher(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Teacher() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String toString() {
        return "Teacher{" + "name='" + name  + ", age=" + age + '}';
    }
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:[e-mail]
*/
package cn.org.yinzhengjie.json;

import com.alibaba.fastjson.JSONObject;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class JsonOperation {
    public static final String filePath =  "D:\\10.Java\\IDE\\yhinzhengjieData\\MyHadoop\\JSON\\teacher.txt";

    public static void main(String[] args) throws Exception {
        generatingJSON();
        System.out.println("=============我是分割線=============");
        parsingJSON();
    }
    //生成json文本
    private static void generatingJSON() throws IOException {
        Teacher yzj = new Teacher("尹正傑", 18);
        String json = JSONObject.toJSONString(yzj);
        System.out.println(json);
        FileOutputStream fos = new FileOutputStream(filePath);
        byte[] buf = new byte[1024];
        fos.write(json.getBytes());
        fos.close();
    }

    //解析json文本
    private static void parsingJSON() throws IOException {
        byte[] buf = new byte[1024];
        FileInputStream fis = new FileInputStream(filePath);
        //由於我的文件較小，為了實驗方便我就一次性讀取出來了
        JSONObject json = JSONObject.parseObject( new String(buf,0,fis.read(buf)));
        System.out.println(json);
    }
}




/*
以上代碼執行結果如下:
{"age":18,"name":"尹正傑"}
=============我是分割線=============
{"name":"尹正傑","age":18}
 */

 

二.Java數據類型和Json互相轉換案例

   以下是list和json字符串的互轉，當然，map的轉換json和其方法類似，我這里就不多舉例了：

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:[e-mail]
*/
package cn.org.yinzhengjie.json;

public class Teacher {
    private String name;
    private int age;

    public Teacher(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public Teacher() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public String toString() {
        return "Teacher{" + "name='" + name  + ", age=" + age + '}';
    }
}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:[e-mail]
*/
package cn.org.yinzhengjie.json;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class JsonOperation {
    17 
    public static void main(String[] args) throws Exception {
        listToJSON();
        System.out.println("=============我是分割線=============");
        jsonToList();
    }
    public static void listToJSON(){
        Teacher yzj = new Teacher("尹正傑",18);
        Teacher yzj1 = new Teacher("yinzhengjie",19);
        Teacher yzj2 = new Teacher("YINZHENGJIE",20);
        List<Teacher> lists=new ArrayList<Teacher>();
        lists.add(yzj);
        lists.add(yzj1);
        lists.add(yzj2);
        String listArray=JSONArray.toJSONString(lists);
        System.out.println("arrayList:"+listArray);
    }

    public static void jsonToList(){
        String str ="{\"names\":[\"尹正傑\",\"yinzhengjie\"]}";
        JSONObject jo = JSON.parseObject(str);
        JSONArray jsonArray = jo.getJSONArray("names");
        for (Object o : jsonArray) {
            System.out.println(o.toString());
        }
    }
}

/*
以上代碼執行結果如下:
arrayList:[{"age":18,"name":"尹正傑"},{"age":19,"name":"yinzhengjie"},{"age":20,"name":"YINZHENGJIE"}]
=============我是分割線=============
尹正傑
yinzhengjie
 */

 

三.小試牛刀

　　是不是覺得json處理其實蠻簡單的，不是嗎？接下來我們來練習以下，解析以下的字符串：需要解析商家評論數據：

{"reviewPics":null,"extInfoList":[{"title":"contentTags","values":["環境優雅","性價比高","干凈衛生","停車方便","音響效果好"],"desc":"","defineType":0},{"title":"tagIds","values":["24","300","852","506","173"],"desc":"","defineType":0}],"expenseList":null,"reviewIndexes":[2],"scoreList":null}

/*
@author :yinzhengjie
Blog:http://www.cnblogs.com/yinzhengjie/tag/Java%E5%9F%BA%E7%A1%80/
EMAIL:[e-mail]
*/
package cn.org.yinzhengjie.json;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class JsonOperation {
   17 
    public static void main(String[] args) throws Exception {
        String comment = "{\"reviewPics\":null,\"extInfoList\":[{\"title\":\"contentTags\",\"values\":[\"環境優雅\",\"性價比高\",\"干凈衛生\",\"停車方便\",\"音響效果好\"],\"desc\":\"\",\"defineType\":0},{\"title\":\"tagIds\",\"values\":[\"24\",\"300\",\"852\",\"506\",\"173\"],\"desc\":\"\",\"defineType\":0}],\"expenseList\":null,\"reviewIndexes\":[2],\"scoreList\":null}";
        List<String> taggen = taggen(comment);
        for (String s : taggen) {
            System.out.println(s);
        }

    }
    /**
     * 解析商家評論數據
     */
    public static List<String> taggen(String comment){
        JSONObject jo = JSON.parseObject(comment);
        JSONArray jArray = jo.getJSONArray("extInfoList");
        if(jArray != null && jArray.size() != 0){
            List<String> list = new ArrayList<String>();
            //通過jArray得到第一個json串，作為json對象
            JSONObject jo2 = jArray.getJSONObject(0);
            JSONArray jArray2 = jo2.getJSONArray("values");
            if(jArray2 != null && jArray2.size() != 0){
                for (Object o : jArray2) {
                    //System.out.println(o.toString());
                    list.add(o.toString());
                }
                return list;
            }
        }
        return null;
    }
}

/*
以上代碼執行結果如下:
環境優雅
性價比高
干凈衛生
停車方便
音響效果好
 */

 

 

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