使用jsonpath解析json内容

2022-09-27 22:20:26

JsonPath提供的json解析非常强大，它提供了类似正则表达式的语法，基本上可以满足所有你想要获得的json内容。下面我把官网介绍的每个表达式用代码实现，可以更直观的知道该怎么用它。

一.首先需要依赖的jar包

使用jsonpath解析json内容

二.因为编译的时候会报log4j的警报，所以需要在项目的src目录下新建log4j.properties文件，内容如下：

log4j.rootLogger=WARN, stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

三.准备一个json文本

{

    "store": {

        "book": [

            {

                "category": "reference",

                "author": "Nigel Rees",

                "title": "Sayings of the Century",

                "price": 8.95

            },

            {

                "category": "fiction",

                "author": "Evelyn Waugh",

                "title": "Sword of Honour",

                "price": 12.99

            },

            {

                "category": "fiction",

                "author": "Herman Melville",

                "title": "Moby Dick",

                "isbn": "0-553-21311-3",

                "price": 8.99

            },

            {

                "category": "fiction",

                "author": "J. R. R. Tolkien",

                "title": "The Lord of the Rings",

                "isbn": "0-395-19395-8",

                "price": 22.99

            }

        ],

        "bicycle": {

            "color": "red",

            "price": 19.95

        }

    },

    "expensive": 10

}

四.我们从代码中分析用法，代码如下

package com.jsonpath;

import java.io.BufferedReader;

import java.io.FileNotFoundException;

import java.io.FileReader;

import java.util.Iterator;

import java.util.List;

import java.util.Map;

import net.minidev.json.JSONArray;

import com.jayway.jsonpath.Configuration;

import com.jayway.jsonpath.JsonPath;

import com.jayway.jsonpath.ReadContext;

/**

 * @author QiaoJiafei

 * @version 创建时间：2016年3月2日 下午3:37:42

 * 类说明

 */

public class TestJsonPath {

    public static void main(String[] args) {

        // TODO Auto-generated method stub

        String sjson = readtxt();

        //String sjson = "{\"store\": {\"book\": [{\"category\": \"reference\",\"author\": \"Nigel Rees\",\"title\": \"Sayings of the Century\",\"price\": 8.95},{\"category\": \"fiction\",\"author\": \"Evelyn Waugh\",\"title\": \"Sword of Honour\",\"price\": 12.99},{\"category\": \"fiction\",\"author\": \"Herman Melville\",\"title\": \"Moby Dick\",\"isbn\": \"0-553-21311-3\",\"price\": 8.99},{\"category\": \"fiction\",\"author\": \"J. R. R. Tolkien\",\"title\": \"The Lord of the Rings\",\"isbn\": \"0-395-19395-8\",\"price\": 22.99}],\"bicycle\": {\"color\": \"red\",\"price\": 19.95}},\"expensive\": 10}";

        /*

        print("--------------------------------------getJsonValue0--------------------------------------");

        getJsonValue0(sjson);

        print("--------------------------------------getJsonValue1--------------------------------------");

        getJsonValue1(sjson);

        print("--------------------------------------getJsonValue2--------------------------------------");

        getJsonValue2(sjson);

        print("--------------------------------------getJsonValue3--------------------------------------");

        getJsonValue3(sjson);

        print("--------------------------------------getJsonValue4--------------------------------------");

        getJsonValue4(sjson);

        */

        print("--------------------------------------getJsonValue--------------------------------------");

        getJsonValue(sjson);

    }

    private static String readtxt() {

        // TODO Auto-generated method stub

        StringBuilder sb = new StringBuilder();

        try {

            FileReader fr = new FileReader("D:/workspace/PressureTest/json.txt");

            BufferedReader bfd = new BufferedReader(fr);

            String s = "";

            while((s=bfd.readLine())!=null) {

                sb.append(s);

            }

        } catch (Exception e) {

            // TODO Auto-generated catch block

            e.printStackTrace();

        }

        System.out.println(sb.toString());

        return sb.toString();

    }

    private static void getJsonValue(String json) {

        //The authors of all books：获取json中store下book下的所有author值

        List<String> authors1 = JsonPath.read(json, "$.store.book[*].author");

        //All authors：获取所有json中所有author的值

        List<String> authors2 = JsonPath.read(json, "$..author");

        //All things, both books and bicycles //authors3返回的是net.minidev.json.JSONArray：获取json中store下的所有value值，不包含key，如key有两个，book和bicycle

        List<Object> authors3 = JsonPath.read(json, "$.store.*");

        //The price of everything：获取json中store下所有price的值

        List<Object> authors4 = JsonPath.read(json, "$.store..price");

        //The third book：获取json中book数组的第3个值

        List<Object> authors5 = JsonPath.read(json, "$..book[2]");

        //The first two books：获取json中book数组的第1和第2两个个值

        List<Object> authors6 = JsonPath.read(json, "$..book[0,1]");

        //All books from index 0 (inclusive) until index 2 (exclusive)：获取json中book数组的前两个区间值

        List<Object> authors7 = JsonPath.read(json, "$..book[:2]");

        //All books from index 1 (inclusive) until index 2 (exclusive)：获取json中book数组的第2个值

        List<Object> authors8 = JsonPath.read(json, "$..book[1:2]");

        //Last two books：获取json中book数组的最后两个值

        List<Object> authors9 = JsonPath.read(json, "$..book[-2:]");

        //Book number two from tail：获取json中book数组的第3个到最后一个的区间值

        List<Object> authors10 = JsonPath.read(json, "$..book[2:]");

        //All books with an ISBN number：获取json中book数组中包含isbn的所有值

        List<Object> authors11 = JsonPath.read(json, "$..book[?(@.isbn)]");

        //All books in store cheaper than 10：获取json中book数组中price<10的所有值

        List<Object> authors12 = JsonPath.read(json, "$.store.book[?(@.price < 10)]");

        //All books in store that are not "expensive"：获取json中book数组中price<=expensive的所有值

        List<Object> authors13 = JsonPath.read(json, "$..book[?(@.price <= $['expensive'])]");

        //All books matching regex (ignore case)：获取json中book数组中的作者以REES结尾的所有值（REES不区分大小写）

        List<Object> authors14 = JsonPath.read(json, "$..book[?(@.author =~ /.*REES/i)]");

        //Give me every thing：逐层列出json中的所有值，层级由外到内

        List<Object> authors15 = JsonPath.read(json, "$..*");

        //The number of books：获取json中book数组的长度

        List<Object> authors16 = JsonPath.read(json, "$..book.length()");

        print("**************authors1**************");

        print(authors1);

        print("**************authors2**************");

        print(authors2);

        print("**************authors3**************");

        printOb(authors3);

        print("**************authors4**************");

        printOb(authors4);

        print("**************authors5**************");

        printOb(authors5);

        print("**************authors6**************");

        printOb(authors6);

        print("**************authors7**************");

        printOb(authors7);

        print("**************authors8**************");

        printOb(authors8);

        print("**************authors9**************");

        printOb(authors9);

        print("**************authors10**************");

        printOb(authors10);

        print("**************authors11**************");

        printOb(authors11);

        print("**************authors12**************");

        printOb(authors12);

        print("**************authors13**************");

        printOb(authors13);

        print("**************authors14**************");

        printOb(authors14);

        print("**************authors15**************");

        printOb(authors15);

        print("**************authors16**************");

        printOb(authors16);

    }

    /**

     * 读取json的一种写法，得到匹配表达式的所有值

     * */

    private static void getJsonValue0(String json) {

        // TODO Auto-generated method stub

        List<String> authors = JsonPath.read(json, "$.store.book[*].author");

        //System.out.println(authors.size());

        print(authors);

    }

    /**

     * 读取json的一种写法，得到某个具体值

     * */

    private static void getJsonValue1(String json) {

        Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);

        String author0 = JsonPath.read(document, "$.store.book[0].author");

        String author1 = JsonPath.read(document, "$.store.book[1].author");

        print(author0);

        print(author1);

    }

    /**

     * 读取json的一种写法

     * */

    private static void getJsonValue2(String json) {

        ReadContext ctx = JsonPath.parse(json);

        List<String> authorsOfBooksWithISBN = ctx.read("$.store.book[?(@.isbn)].author");

        List<Map<String, Object>> expensiveBooks = JsonPath

                                    .using(Configuration.defaultConfiguration())

                                    .parse(json)

                                    .read("$.store.book[?(@.price > 10)]", List.class);

        print(authorsOfBooksWithISBN);

        print("****************Map****************");

        printListMap(expensiveBooks);

    }

    /**

     *读取json的一种写法

     *得到的值是一个String，所以不能用List存储

     * */

    private static void getJsonValue3(String json) {

        //Will throw an java.lang.ClassCastException

        //List<String> list = JsonPath.parse(json).read("$.store.book[0].author");

        //由于会抛异常，暂时注释上面一行，要用的话，应使用下面的格式

        //Works fine

        String author = JsonPath.parse(json).read("$.store.book[0].author");

        print(author);

    }

    /**

     *读取json的一种写法

     *支持逻辑表达式，&&和||

     * */

    private static void getJsonValue4(String json) {

        List<Map<String, Object>> books1 =  JsonPath.parse(json)

                .read("$.store.book[?(@.price < 10 && @.category == 'fiction')]");

        List<Map<String, Object>> books2 =  JsonPath.parse(json)

                .read("$.store.book[?(@.category == 'reference' || @.price > 10)]");

        print("****************books1****************");

        printListMap(books1);

        print("****************books2****************");

        printListMap(books1);

    }

    private static void print(List<String> list) {

        for(Iterator<String> it = list.iterator();it.hasNext();) {

            System.out.println(it.next());

        }

    }

    private static void printOb(List<Object> list) {

        for(Iterator<Object> it = list.iterator();it.hasNext();) {

            print("****");

            System.out.println(it.next());

        }

    }

    private static void printListMap(List<Map<String, Object>> list) {

        for(Iterator<Map<String, Object>> it = list.iterator();it.hasNext();) {

            Map<String, Object> map = it.next();

            print("****");

            for(Iterator iterator =map.entrySet().iterator();iterator.hasNext();) {

                System.out.println(iterator.next());

            }

        }

    }

    private static void print(String s) {

        System.out.println(s);

    }

}

1.首先我们看getJsonValue()这个方法的输出结果：

--------------------------------------getJsonValue--------------------------------------

**************authors1**************

Nigel Rees

Evelyn Waugh

Herman Melville

J. R. R. Tolkien

**************authors2**************

Nigel Rees

Evelyn Waugh

Herman Melville

J. R. R. Tolkien

**************authors3**************

[{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95},{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99},{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}]

{color=red, price=19.95}

**************authors4**************

8.95

12.99

8.99

22.99

19.95

**************authors5**************

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

**************authors6**************

{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}

{category=fiction, author=Evelyn Waugh, title=Sword of Honour, price=12.99}

**************authors7**************

{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}

{category=fiction, author=Evelyn Waugh, title=Sword of Honour, price=12.99}

**************authors8**************

{category=fiction, author=Evelyn Waugh, title=Sword of Honour, price=12.99}

**************authors9**************

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}

**************authors10**************

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}

**************authors11**************

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}

**************authors12**************

{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

**************authors13**************

{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

**************authors14**************

{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}

**************authors15**************

{book=[{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95},{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99},{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}], bicycle={color=red, price=19.95}}

10

[{"category":"reference","author":"Nigel Rees","title":"Sayings of the Century","price":8.95},{"category":"fiction","author":"Evelyn Waugh","title":"Sword of Honour","price":12.99},{"category":"fiction","author":"Herman Melville","title":"Moby Dick","isbn":"0-553-21311-3","price":8.99},{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}]

{color=red, price=19.95}

{category=reference, author=Nigel Rees, title=Sayings of the Century, price=8.95}

{category=fiction, author=Evelyn Waugh, title=Sword of Honour, price=12.99}

{category=fiction, author=Herman Melville, title=Moby Dick, isbn=0-553-21311-3, price=8.99}

{category=fiction, author=J. R. R. Tolkien, title=The Lord of the Rings, isbn=0-395-19395-8, price=22.99}

reference

Nigel Rees

Sayings of the Century

8.95

fiction

Evelyn Waugh

Sword of Honour

12.99

fiction

Herman Melville

Moby Dick

0-553-21311-3

8.99

fiction

J. R. R. Tolkien

The Lord of the Rings

0-395-19395-8

22.99

red

19.95

**************authors16**************

4

2.然后看getJsonValue0()、getJsonValue1()、getJsonValue2()、getJsonValue3()、getJsonValue4()的输出结果

--------------------------------------getJsonValue0--------------------------------------

Nigel Rees

Evelyn Waugh

Herman Melville

J. R. R. Tolkien

--------------------------------------getJsonValue1--------------------------------------

Nigel Rees

Evelyn Waugh

--------------------------------------getJsonValue2--------------------------------------

Herman Melville

J. R. R. Tolkien

****************Map****************

****

category=fiction

author=Evelyn Waugh

title=Sword of Honour

price=12.99

****

category=fiction

author=J. R. R. Tolkien

title=The Lord of the Rings

isbn=0-395-19395-8

price=22.99

--------------------------------------getJsonValue3--------------------------------------

Nigel Rees

--------------------------------------getJsonValue4--------------------------------------

****************books1****************

****

category=fiction

author=Herman Melville

title=Moby Dick

isbn=0-553-21311-3

price=8.99

****************books2****************

****

category=fiction

author=Herman Melville

title=Moby Dick

isbn=0-553-21311-3

price=8.99

3.相应的解释已经在代码中注释，更多的用法详见官网链接：https://github.com/jayway/JsonPath

4.如果只是想简单的处理json，也可以使用JSONObject和JSONArray，具体用法详见我的这篇文章：http://www.cnblogs.com/qiaoyeye/p/4730930.html

----------更新2016年08月19日10:06:09-------

You can use && and || to combine multiple predicates [?(@.price < 10 && @.category == 'fiction')] , [?(@.category == 'reference' || @.price > 10)]

这个好厉害，可以这样用

JsonPath.read(json, "$..farePrices[?(@.priceType == 'SalePrice' && @.passengerType == 'ADULT')].amount");

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