FastJson解析JSON数据

程序员文章站 2022-06-17 09:05:55

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阿里巴巴FastJson是一个Json处理工具包，包括“序列化”和“反序列化”两部分，它具备如下特征：
速度最快，测试表明，fastjson具有极快的性能，超越任其他的Java Json parser。包括自称最快的JackJson；
功能强大，完全支持Java Bean、集合、Map、日期、Enum，支持范型，支持自省；无依赖，能够直接运行在Java SE 5.0以上版本；支持Android；开源 (Apache 2.0)

源码地址：https://github.com/alibaba/fastjson

Fastjson API入口类是com.alibaba.fastjson.JSON，常用的序列化操作都可以在JSON类上的静态方法直接完成。

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

以上加*的是一些项目中的常用方法。

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为什么使用FastJson?
解析速度快、解析方便、使用简单。

首先，看一下解析的代码量

iu = Fast.parseObject(JsonString.JsonStringValues, Info_util.class);//取得第一层JSONObject
du = Fast.parseObject(iu.getData(), Info_data_util.class);//取得第二层JSONObject
olist = Fast.parseArray(du.getRows(), Info_array_Util.class);//取得第三层JSONArray

就两三行代码。再来看看以前常用的JsonObject以及JsonArray解析

JSONObject result= new JSONObject(jsonString);  
JSONArray jsonArray = result .getJSONArray("List");  
for (int i = 0; i < jsonArray.length; i++) {  
   JSONObject json=jsonArray.getJSONObject(i);
   json.getString("...");
   ...
   ...
}

这种一个个去获取，很麻烦。

使用FastJson的方法如下：

需要下载FastJson的jar包，我是利用eclipse工具+Maven；
不需要单独下载jar包，只需要修改pom.xml文件；

pom.xml文件如下：

<!-- https://mvnrepository.com/artifact/com.alibaba/fastjson -->
	<dependency>
	    <groupId>com.alibaba</groupId>
	    <artifactId>fastjson</artifactId>
	    <version>1.2.46</version>
	</dependency>
	
	<!-- https://mvnrepository.com/artifact/junit/junit -->
	<dependency>
	    <groupId>junit</groupId>
	    <artifactId>junit</artifactId>
	    <version>4.12</version>
	    <scope>test</scope>
	</dependency>

有一串这样的Json数据：

{
    "status": 1,
    "msg": null,
    "data": {
        "start": 0,
        "limit": 10,
        "total": 5,
        "rows": [
            {
                "messageNo": "Me201607211148242364423",
                "memberNo": "AD2016070812145640900000003",
                "mobileNo": "151****1314",
                "nickname": "远方",
                "headPath": "/fileupload/memberImage/83788978A0614007BF7F5D20F668088A1468667650848.jpg",
                "messageType": 0,
                "readFlag": 0,
                "sendTime": 1469072904000,
                "content": "   ",
                "updateTime": 1469072904000
            },
            {
                "messageNo": "Me201607211146458551987",
                "memberNo": "AD2016070812145640900000003",
                "mobileNo": "151****1314",
                "nickname": "远方",
                "headPath": "/fileupload/memberImage/83788978A0614007BF7F5D20F668088A1468667650848.jpg",
                "messageType": 0,
                "readFlag": 0,
                "sendTime": 1469072805000,
                "content": "有6",
                "updateTime": 1469072805000
            },
            {
                "messageNo": "Me201607191730505629442",
                "memberNo": "AD2016070810124275700000002",
                "mobileNo": "156****3913",
                "nickname": "呵呵",
                "headPath": "/fileupload/memberImage/FD5DAE12CB79447BB5263EB0EE4E75F41469069984778.jpg",
                "messageType": 0,
                "readFlag": 0,
                "sendTime": 1468920650000,
                "content": "额",
                "updateTime": 1468920650000
            },
            {
                "messageNo": "Me201607161049255579387",
                "memberNo": "AD2016070812145640900000003",
                "mobileNo": "151****1314",
                "nickname": "远方",
                "headPath": "/fileupload/memberImage/83788978A0614007BF7F5D20F668088A1468667650848.jpg",
                "messageType": 1,
                "readFlag": 0,
                "sendTime": 1468637365000,
                "content": "111",
                "updateTime": 1468637365000
            },
            {
                "messageNo": "Me201607161037444613493",
                "memberNo": "AD2016070812145640900000003",
                "mobileNo": "151****1314",
                "nickname": "远方",
                "headPath": "/fileupload/memberImage/83788978A0614007BF7F5D20F668088A1468667650848.jpg",
                "messageType": 0,
                "readFlag": 0,
                "sendTime": 1468636664000,
                "content": "哈哈哈",
                "updateTime": 1468636664000
            }
        ],
        "otherData": null
    }
}

这串Json数据分为3层，最外层的”status”，”msg”和”data”；然后”data”里面的”start”，”limit”，”total”，”rows”；最后”rows”里面的JSONArray。

FastJson解析JSON数据

源代码如下：

JsonString.java：

package com.accord.fastjson;

public class JsonString {
    public static final String JsonStringValues = "{\"status\":1,\"msg\":null,"
            + "\"data\":{\"start\":0,\"limit\":10,\"total\":5,"
            + "\"rows\":[{\"messageNo\":\"Me201607211148242364423\","
            + "\"memberNo\":\"AD2016070812145640900000003\","
            + "\"mobileNo\":\"151****1314\","
            + "\"nickname\":\"远方\","
            + "\"headPath\":\"/fileupload/memberImage/83788978A0614007BF7F5D20F668088A1468667650848.jpg\","
            + "\"messageType\":0,"
            + "\"readFlag\":0,"
            + "\"sendTime\":1469072904000,"
            + "\"content\":\"   \","
            + "\"updateTime\":1469072904000},"
            + "{\"messageNo\":\"Me201607211146458551987\","
            + "\"memberNo\":\"AD2016070812145640900000003\","
            + "\"mobileNo\":\"151****1314\","
            + "\"nickname\":\"远方\","
            + "\"headPath\":\"/fileupload/memberImage/83788978A0614007BF7F5D20F668088A1468667650848.jpg\","
            + "\"messageType\":0,"
            + "\"readFlag\":0,"
            + "\"sendTime\":1469072805000,"
            + "\"content\":\"有6\","
            + "\"updateTime\":1469072805000},{\"messageNo\":\"Me201607191730505629442\",\"memberNo\":\"AD2016070810124275700000002\",\"mobileNo\""
            + ":\"156****3913\",\"nickname\":\"呵呵\",\"headPath\":\"/fileupload/memberImage/FD5DAE12CB7944"
            + "7BB5263EB0EE4E75F41469069984778.jpg\",\"messageType\":0,\"readFlag\":0,\"sendTime\":1468"
            + "920650000,\"content\":\"额\",\"updateTime\":1468920650000},{\"messageNo\":\"Me2016071610"
            + "49255579387\",\"memberNo\":\"AD2016070812145640900000003\",\"mobileNo\":\"151****1314\",\"nic"
            + "kname\":\"远方\",\"headPath\":\"/fileupload/memberImage/83788978A0614007BF7F5D20F668088A14686"
            + "67650848.jpg\",\"messageType\":1,\"readFlag\":0,\"sendTime\":1468637365000,\"content\":\"111\",\"upda"
            + "teTime\":1468637365000},{\"messageNo\":\"Me201607161037444613493\",\"memberNo\":\"AD20160708121456409"
            + "00000003\",\"mobileNo\":\"151****1314\",\"nickname\":\"远方\",\"headPath\":\"/fileupload/memberImage/8"
            + "3788978A0614007BF7F5D20F668088A1468667650848.jpg\",\"messageType\":0,\"readFlag\":0,\"sendTime\":146"
            + "8636664000,\"content\":\"哈哈哈\",\"updateTime\":1468636664000}],\"otherData\":null}}";

}

存储数据用的 3个 Setter and Getter封装类(因为Json数据有3层所以有3个)
Info_util.java:

package com.accord.fastjson;

public class Info_util {
    private int status;
    private String msg, data;

    @Override
    public String toString() {
        return " status=" + status + ", msg=" + msg + ", data=" + data;
    }

    public int getStatus() {
        return status;
    }

    public void setStatus(int status) {
        this.status = status;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

    public String getData() {
        return data;
    }

    public void setData(String data) {
        this.data = data;
    }
}

Info_data_util.java

package com.accord.fastjson;

public class Info_data_util {
	private int start, limit, total;
    private String rows;

    @Override
    public String toString() {
        return " start=" + start + ", limit=" + limit + ", total=" + total
                + ", rows=" + rows;
    }

    public String getRows() {
        return rows;
    }

    public void setRows(String rows) {
        this.rows = rows;
    }


    public int getStart() {
        return start;
    }

    public void setStart(int start) {
        this.start = start;
    }

    public int getLimit() {
        return limit;
    }

    public void setLimit(int limit) {
        this.limit = limit;
    }

    public int getTotal() {
        return total;
    }

    public void setTotal(int total) {
        this.total = total;
    }
}

Info_array_util.java

package com.accord.fastjson;

public class Info_array_Util {
	private String messageNo, memberNo, mobileNo, nickname, headPath, content;
    private int messageType, readFlag;
    private long sendTime, updateTime;

    @Override
    public String toString() {
        return " messageNo=" + messageNo + ", memberNo="
                + memberNo + ", mobileNo=" + mobileNo + ", nickname="
                + nickname + ", headPath=" + headPath + ", content=" + content
                + ", messageType=" + messageType + ", readFlag=" + readFlag
                + ", sendTime=" + sendTime + ", updateTime=" + updateTime ;
    }

    public String getMessageNo() {
        return messageNo;
    }

    public void setMessageNo(String messageNo) {
        this.messageNo = messageNo;
    }

    public String getMemberNo() {
        return memberNo;
    }

    public void setMemberNo(String memberNo) {
        this.memberNo = memberNo;
    }

    public String getMobileNo() {
        return mobileNo;
    }

    public void setMobileNo(String mobileNo) {
        this.mobileNo = mobileNo;
    }

    public String getNickname() {
        return nickname;
    }

    public void setNickname(String nickname) {
        this.nickname = nickname;
    }

    public String getHeadPath() {
        return headPath;
    }

    public void setHeadPath(String headPath) {
        this.headPath = headPath;
    }

    public String getContent() {
        return content;
    }

    public void setContent(String content) {
        this.content = content;
    }

    public int getMessageType() {
        return messageType;
    }

    public void setMessageType(int messageType) {
        this.messageType = messageType;
    }

    public int getReadFlag() {
        return readFlag;
    }

    public void setReadFlag(int readFlag) {
        this.readFlag = readFlag;
    }

    public long getSendTime() {
        return sendTime;
    }

    public void setSendTime(long sendTime) {
        this.sendTime = sendTime;
    }

    public long getUpdateTime() {
        return updateTime;
    }

    public void setUpdateTime(long updateTime) {
        this.updateTime = updateTime;
    }
}

然后要用的工具类，已经写好，其他项目也可以直接用，无需改动。

Fast.java

package com.accord.fastjson;

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

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.TypeReference;

/**
 * 然后要用的工具类，已经写好，其他项目也可以直接用，无需改动。
 * @author 王久印
 * 2018年2月6日
 */
public class Fast {
	/**
     * 解析JsonObject数据
     * 
     * @param jsonString
     *            Json格式字符串
     * @param cls
     *            封装类
     * 
     */
    public static <T> T parseObject(String jsonString, Class<T> cls) {
        T t = null;
        try {
            t = JSON.parseObject(jsonString, cls);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return t;
    }

    /**
     * 解析JsonArray数据
     * 
     * @param jsonString
     * @param cls
     * @return
     */
    public static <T> List<T> parseArray(String jsonString, Class<T> cls) {
        List<T> list = new ArrayList<T>();
        try {
            list = JSON.parseArray(jsonString, cls);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }

    /**
     * 解析JsonArray数据，返回Map类型的List
     * 
     * @param jsonString
     * @return
     */
    public static List<Map<String, Object>> parseObjectListKeyMaps(
            String jsonString) {
        List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
        try {
            list = JSON.parseObject(jsonString,
                    new TypeReference<List<Map<String, Object>>>() {
                    });
        } catch (Exception e) {
            e.printStackTrace();
        }
        return list;
    }
}

现在就可以解析Json数据了：

Main.java

package com.accord.fastjson;

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

public class Main {
	public static void main(String[] args) {
		Info_util iu = new Info_util();
	    Info_data_util du = new Info_data_util();
	    List<Info_array_Util> olist = new ArrayList<Info_array_Util>();
	    iu = Fast.parseObject(JsonString.JsonStringValues, Info_util.class);//取得第一层JSONObject
        du = Fast.parseObject(iu.getData(), Info_data_util.class);//取得第二层JSONObject
        olist = Fast.parseArray(du.getRows(), Info_array_Util.class);//取得第三层JSONArray

        /**
         * 打印解析结果
         */
        StringBuffer bu = new StringBuffer();
        for (int i = 0; i < olist.size(); i++) {
            bu.append("jsonArray第" + (i + 1) + "条数据:\n" + olist.get(i).toString() + "\n\n");
        }
        System.out.println("bu:" + bu);
        System.out.println("jsonObject数据：\n\n" + iu.toString() + "\n\n" + du.toString() + "\n\n\n\n" + "jsonArray数据:\n" + "\n" + bu);
	}
}

除去必要的3个封装类，解析Json的就那么三行代码，如果Json数据结构简单甚至可能只需要一行代码。

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