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阿里巴巴FastJson对数据的常用操作

更新时间:2019年03月21日18时01分 来源:传智播客

  Fastjson是一个Java语言编写的高性能功能完善的JSON库。它采用一种“假定有序快速匹配”的算法,把JSON Parse的性能提升到极致,是目前Java语言中最快的JSON库。Fastjson接口简单易用,已经被广泛使用在缓存序列化、协议交互、Web输出、Android客户端等多种应用场景。

  maven工程可以在pom文件加入依赖

<dependency>
     <groupId>com.alibaba</groupId>
     <artifactId>fastjson</artifactId>
     <version>1.2.21</version>
</dependency>

  fastjson入口类是com.alibaba.fastjson.JSON,主要的API是JSON.toJSONString,和parseObject。

  常用的序列化操作都可以在JSON类上的静态方法直接完成。

// 把JSON文本parse为JSONObject或者JSONArray
public static final Object parse(String text);
// 把JSON文本parse成JSONObject   
public static final JSONObject parseObject(String text);
// 把JSON文本parse为JavaBean
public static final <T> T parseObject(String text, Class<T> clazz);
// 把JSON文本parse成JSONArray
public static final JSONArray parseArray(String text);
//把JSON文本parse成JavaBean集合
public static final <T> List<T> parseArray(String text, Class<T> clazz);
// 将JavaBean序列化为JSON文本
public static final String toJSONString(Object object);
// 将JavaBean序列化为带格式的JSON文本
public static final String toJSONString(Object object, boolean prettyFormat);
//将JavaBean转换为JSONObject或者JSONArray。
public static final Object toJSON(Object javaObject);

-----------------------------------------------------------
//序列化:
String jsonString = JSON.toJSONString(obj);
//反序列化:
VO vo = JSON.parseObject("...", VO.class);
//泛型反序列化:
import com.alibaba.fastjson.TypeReference;
List<VO> list = JSON.parseObject("...", new TypeReference<List<VO>>() {});

  下面贴出自己代码,相当于是FastJson使用操作的一个集合,基本上满足开发中绝大部分的json解析和拼接了。


package heima.itcast.demo;
import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
import heima.itcast.demo.model.Book;
import java.util.*;
public class Test {
    public static void main(String[] args) {
        //String转化为实体类Book
        StrToObject();
        //String转化为jsonObject
        StrToJsonObject();
        //实体类转换为json
        //多个实体类转换为json数组形式的string
        //String转化为List<Book>
        StrToListObject();
        //String转化为数组
        //String转化为ArrayList
        StrToArrayList();
        //map和json互相转换
        mapTo();
    }
    /**
     * String转化为实体类Book
     */
    public static void StrToObject() {
        StringBuilder sb = new StringBuilder();
        sb.append("{");
        sb.append("\"name\": \"教父三部曲\",");
        sb.append(" \"author\": \"马里奥·普佐\",");
        sb.append("  \"price\": \"100\"");
        sb.append("}");
        Book book = JSON.parseObject(sb.toString(), Book.class);
        System.out.println("书名:"+book.getName()+";作者:"+book.getAuthor()+";价格:"+book.getPrice());
    }
    /**
     * String转化为jsonObject
     */
    public static void StrToJsonObject() {
        StringBuilder sb = new StringBuilder();
        sb.append("{");
        sb.append("\"name\": \"教父三部曲\",");
        sb.append(" \"author\": \"马里奥·普佐\",");
        sb.append("  \"price\": \"100\"");
        sb.append("}");
        JSONObject jsonObj = JSON.parseObject(sb.toString());
        for(Map.Entry<String, Object> entry : jsonObj.entrySet()){
            System.out.println(entry.getKey()+"--"+entry.getValue());
        }
    }
    /**
     * 实体类转换为json
     * 多个实体类转换为json数组形式的string
     * String转化为List<Book>
     */
    public static void StrToListObject() {
        List<Book> bookList =  new ArrayList<>();
        Book book1 = new Book("教父三部曲","马里奥·普佐",100) ;
        Book book2 = new Book("天才在左疯子在右","高铭",30) ;
        bookList.add(book1);
        bookList.add(book2);
        //实体类转换为json
        String book1Str = JSON.toJSONString(book1);
        //多个实体类转换为json数组形式的string
        String bookStr = JSON.toJSONString(bookList);
        //String转化为List<Book>
        List<Book> bookList3 = JSON.parseArray(bookStr,Book.class);
    }
    /**
     * String转化为数组
     * String转化为ArrayList
     */
    public static void StrToArrayList(){
        StringBuilder sb = new StringBuilder();
        sb.append("[{");
        sb.append("\"name\": \"教父三部曲\",");
        sb.append(" \"author\": \"马里奥·普佐\",");
        sb.append("  \"price\": \"100\"");
        sb.append("}]");
        // String转化为数组
        Book[] arrBook = JSON.parseObject(sb.toString(),new TypeReference<Book[]>(){});
        List<Book> list = Arrays.asList(arrBook);
        for (int i = 0; i < arrBook.length; i++) {
            System.out.println(arrBook[i].toString());
        }
        // String转化为ArrayList
        ArrayList<Book> bookList=  JSON.parseObject(sb.toString(),new TypeReference<ArrayList<Book>>(){});
        for(Book book : bookList){
            System.out.println(book.toString());
        }
    }
    /**
     * map和json互相转换
     */
    public static void mapTo(){
        Map<String,String> map = new HashMap<>();
        map.put("name", "教父三部曲");
        map.put("author", "马里奥·普佐");
        map.put("price", "100");
        //map转换为json
        String json = JSON.toJSONString(map);
        //json转换为map
        Map map1 = JSON.parseObject(json);
        System.out.println(map1.toString());
        Map<String,String> map2 = (Map<String,String>)JSON.parse(json);
    }
}
附Book类代码

package heima.itcast.demo.model;
public class Book {
    private String name;
    private String author;
    private int price;
    public Book() {
    }
    public Book(String name, String author, int price) {
        this.name = name;
        this.author = author;
        this.price = price;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAuthor() {
        return author;
    }
    public void setAuthor(String author) {
        this.author = author;
    }
    public int getPrice() {
        return price;
    }
    public void setPrice(int price) {
        this.price = price;
    }
}


作者:传智播客JavaEE培训学院

首发:http://java.itcast.cn