在 JsonPath 中，最简单直接的方法是通过静态方法 read() 读取 JSON 内容，如下：
package com.hxstrive.json_path;
import com.jayway.jsonpath.JsonPath;
import java.util.List;
/**
* Jayway JsonPath 入门示例
* @author hxstrive.com
*/
public class Demo {
public static void main(String[] args) {
String json = "{" +
" \"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" +
"}";
// 获取所有书籍的作者
List<String> authors = JsonPath.read(json, "$.store.book[*].author");
for(String author : authors) {
System.out.println("author: " + author);
}
// 输出：
//author: Nigel Rees
//author: Evelyn Waugh
//author: Herman Melville
//author: J. R. R. Tolkien
}
}如果你只想读取一次，上面的做法是没有问题的。如果您还需要读取其他路径，这就不是办法了，因为每次调用 JsonPath.read(...) 都会对文档进行解析。为了避免这个问题，可以先解析 json，然后在基于解析后的对象进行读取，例如：
package com.hxstrive.json_path;
import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.JsonPath;
import java.util.List;
/**
* Jayway JsonPath 入门示例
* @author hxstrive.com
*/
public class Demo2 {
public static void main(String[] args) {
String json = "{" +
" \"store\": {" +
" \"book\": [" +
" {" +
" \"category\": \"reference\"," +
" \"author\": \"Nigel Rees\"," +
" \"title\": \"Sayings of the Century\"," +
" \"price\": 8.95" +
" }," +
" {" +
" \"category\": \"fiction\"," +
" \"author\": \"Evelyn Waugh\"," +
" \"title\": \"Sword of Honour\"," +
" \"price\": 12.99" +
" }," +
" {" +
" \"category\": \"fiction\"," +
" \"author\": \"Herman Melville\"," +
" \"title\": \"Moby Dick\"," +
" \"isbn\": \"0-553-21311-3\"," +
" \"price\": 8.99" +
" }," +
" {" +
" \"category\": \"fiction\"," +
" \"author\": \"J. R. R. Tolkien\"," +
" \"title\": \"The Lord of the Rings\"," +
" \"isbn\": \"0-395-19395-8\"," +
" \"price\": 22.99" +
" }" +
" ]," +
" \"bicycle\": {" +
" \"color\": \"red\"," +
" \"price\": 19.95" +
" }" +
" }," +
" \"expensive\": 10" +
"}";
Object document = Configuration.defaultConfiguration().jsonProvider().parse(json);
// 获取所有书籍的作者
List<String> authors = JsonPath.read(document, "$.store.book[*].author");
System.out.println("authors=" + authors);
// 获取 expensive 的值
int expensive = JsonPath.read(document, "$.expensive");
System.out.println("expensive=" + expensive);
// 获取 color 的值
String color = JsonPath.read(document, "$.store.bicycle.color");
System.out.println("color=" + expensive);
}
}运行示例，输出内容：
authors=["Nigel Rees","Evelyn Waugh","Herman Melville","J. R. R. Tolkien"] expensive=10 color=10
注意，JsonPath 还提供了一种链式的应用程序接口，这也是最灵活的一种，例如：
package com.hxstrive.json_path;
import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.ReadContext;
import java.util.List;
/**
* Jayway JsonPath 入门示例
* @author hxstrive.com
*/
public class Demo3 {
public static void main(String[] args) {
String json = "{" +
" \"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" +
"}";
ReadContext ctx = JsonPath.parse(json);
List<String> authorsOfBooksWithISBN = ctx.read("$.store.book[?(@.isbn)].author");
System.out.println(authorsOfBooksWithISBN);
}
}
// 输出结果：["Herman Melville","J. R. R. Tolkien"]或者
package com.hxstrive.json_path;
import com.jayway.jsonpath.Configuration;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.ReadContext;
import java.util.List;
import java.util.Map;
/**
* Jayway JsonPath 入门示例
* @author hxstrive.com
*/
public class Demo4 {
public static void main(String[] args) {
String json = "{" +
" \"store\": {" +
" \"book\": [" +
" {" +
" \"category\": \"reference\"," +
" \"author\": \"Nigel Rees\"," +
" \"title\": \"Sayings of the Century\"," +
" \"price\": 8.95" +
" }," +
" {" +
" \"category\": \"fiction\"," +
" \"author\": \"Evelyn Waugh\"," +
" \"title\": \"Sword of Honour\"," +
" \"price\": 12.99" +
" }," +
" {" +
" \"category\": \"fiction\"," +
" \"author\": \"Herman Melville\"," +
" \"title\": \"Moby Dick\"," +
" \"isbn\": \"0-553-21311-3\"," +
" \"price\": 8.99" +
" }," +
" {" +
" \"category\": \"fiction\"," +
" \"author\": \"J. R. R. Tolkien\"," +
" \"title\": \"The Lord of the Rings\"," +
" \"isbn\": \"0-395-19395-8\"," +
" \"price\": 22.99" +
" }" +
" ]," +
" \"bicycle\": {" +
" \"color\": \"red\"," +
" \"price\": 19.95" +
" }" +
" }," +
" \"expensive\": 10" +
"}";
List<Map<String, Object>> expensiveBooks = JsonPath
.using(Configuration.defaultConfiguration())
.parse(json)
.read("$.store.book[?(@.price > 20)]", List.class);
System.out.println(expensiveBooks);
}
}
// 输出结果：[{"category":"fiction","author":"J. R. R. Tolkien","title":"The Lord of the Rings","isbn":"0-395-19395-8","price":22.99}]
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