- html - 出于某种原因,IE8 对我的 Sass 文件中继承的 html5 CSS 不友好?
- JMeter 在响应断言中使用 span 标签的问题
- html - 在 :hover and :active? 上具有不同效果的 CSS 动画
- html - 相对于居中的 html 内容固定的 CSS 重复背景?
我正在尝试解析 JSON file text.json 的内容通过使用 Jackson 库。
我想要的是创建一个 java 方法来获取它的所有键和值,但到目前为止,在我的代码中我只获得了 JSON 文件的第一个键和第一个值。
我用作制作自己的 Java 类的指南的代码片段如下:
public void parse(String json) {
JsonFactory factory = new JsonFactory();
ObjectMapper mapper = new ObjectMapper(factory);
JsonNode rootNode = mapper.readTree(json);
Iterator<Map.Entry<String,JsonNode>> fieldsIterator = rootNode.fields();
while (fieldsIterator.hasNext()) {
Map.Entry<String,JsonNode> field = fieldsIterator.next();
System.out.println("Key: " + field.getKey() + "\tValue:" + field.getValue());
}
}
我创建的 Java 类如下所示:
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.JsonParser;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
public class JacksonStreamExample {
public static void main(String[] args) {
try {
//Create a JsonFactory instance
JsonFactory factory = new JsonFactory();
//Create a JsonParser instance to read from file c:\\text.json
JsonParser jParser = factory.createJsonParser(new File("c:\\text.json"));
/*Create an ObjectMapper instance to provide a pointer
* to root node of the tree after reading the JSON
*/
ObjectMapper mapper = new ObjectMapper(factory);
//Create tree from JSON
JsonNode rootNode = mapper.readTree(jParser);
Iterator<Map.Entry<String,JsonNode>> fieldsIterator = rootNode.getFields();
while (fieldsIterator.hasNext()) {
Map.Entry<String,JsonNode> field = fieldsIterator.next();
System.out.println("Key: " + field.getKey() + "\tValue:" + field.getValue());
}
jParser.close();
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
我的 Eclipse 输出如下,它只创建了一对(键值):
Key: cells Value:[{"type":"basic.Circle","size":{"width":90,"height":54},"position":{"x":-80,"y":200},"angle":0,"id":"cae4c219-c2cd-4a4b-b50c-0f269963ca24","embeds":"","z":1,"wi_name":"START","wi_displayName":"START","wi_description":"","wi_join":"<None>","wi_split":"<None>","wi_performingRole":"<None>","wi_expected_activity_time":null,"wi_expected_user_time":null,"wi_maximum_activity_time":null,"wi_initial_delay":null,"wi_time_unit":"Seconds","wi_required_transitions_for_AND_JOIN":null,"wi_custom_page":"","attrs":{"circle":{"fill":"#000000","width":50,"height":30,"stroke-width":1,"stroke-dasharray":"0"},"text":{"font-size":10,"text":"START","fill":"#ffffff","font-family":"Arial","stroke":"#000000","stroke-width":0,"font-weight":400}}},{"type":"basic.Circle","size":{"width":90,"height":54},"position":{"x":210,"y":200},"angle":0,"id":"d23133e0-e516-4f72-8127-292545d3d479","embeds":"","z":2,"wi_name":"END","wi_displayName":"END","wi_description":"","wi_join":"<None>","wi_split":"<None>","wi_performingRole":"<None>","wi_expected_activity_time":null,"wi_expected_user_time":null,"wi_maximum_activity_time":null,"wi_initial_delay":null,"wi_time_unit":"Seconds","wi_required_transitions_for_AND_JOIN":null,"wi_custom_page":"","attrs":{"circle":{"fill":"#000000","width":50,"height":30,"stroke-width":1,"stroke-dasharray":"0"},"text":{"font-size":10,"text":"END","fill":"#ffffff","font-family":"Arial","stroke":"#000000","stroke-width":0,"font-weight":400}}},{"type":"basic.Rect","position":{"x":-80,"y":370},"size":{"width":90,"height":54},"angle":0,"id":"a53898a5-c018-45c4-bd3f-4ea4d69f58ed","embeds":"","z":3,"wi_name":"ACTIVITY_1","wi_displayName":"ACTIVITY 1","wi_description":"","wi_join":"<None>","wi_split":"<None>","wi_performingRole":"<None>","wi_expected_activity_time":null,"wi_expected_user_time":null,"wi_maximum_activity_time":null,"wi_initial_delay":null,"wi_time_unit":"Seconds","wi_required_transitions_for_AND_JOIN":null,"wi_custom_page":"","attrs":{"rect":{"width":50,"height":30,"rx":2,"ry":2,"stroke-width":1,"stroke-dasharray":"0"},"text":{"text":"Activity","font-size":10,"font-family":"Arial","stroke":"#000000","stroke-width":0,"font-weight":400}}},{"type":"basic.Rect","position":{"x":220,"y":370},"size":{"width":90,"height":54},"angle":0,"id":"e2bd21f2-508d-44b9-9f68-e374d4fa87ea","embeds":"","z":4,"wi_name":"ACTIVITY_2","wi_displayName":"ACTIVITY 2","wi_description":"","wi_join":"<None>","wi_split":"<None>","wi_performingRole":"<None>","wi_expected_activity_time":null,"wi_expected_user_time":null,"wi_maximum_activity_time":null,"wi_initial_delay":null,"wi_time_unit":"Seconds","wi_required_transitions_for_AND_JOIN":null,"wi_custom_page":"","attrs":{"rect":{"width":50,"height":30,"rx":2,"ry":2,"stroke-width":1,"stroke-dasharray":"0"},"text":{"text":"Workitem","font-size":10,"font-family":"Arial","stroke":"#000000","stroke-width":0,"font-weight":400}}},{"type":"link","source":{"id":"cae4c219-c2cd-4a4b-b50c-0f269963ca24"},"target":{"id":"d23133e0-e516-4f72-8127-292545d3d479"},"router":{"name":"manhattan"},"labels":[{"position":0.5,"attrs":{"text":{"text":"Name"}}}],"id":"60ee7ff7-3a3b-487d-b581-49027e7bebe4","embeds":"","z":5,"attrs":{".marker-source":{"d":"M 10 0 L 0 5 L 10 10 z","transform":"scale(0.001)"},".marker-target":{"d":"M 10 0 L 0 5 L 10 10 z"},".connection":{"stroke":"black"}}},{"type":"link","source":{"id":"a53898a5-c018-45c4-bd3f-4ea4d69f58ed"},"target":{"id":"e2bd21f2-508d-44b9-9f68-e374d4fa87ea"},"router":{"name":"manhattan"},"labels":[{"position":0.5,"attrs":{"text":{"text":"Name"}}}],"id":"cea0d1c2-2c18-4bd7-ba35-d94918c6fc9b","embeds":"","z":6,"attrs":{".marker-source":{"d":"M 10 0 L 0 5 L 10 10 z","transform":"scale(0.001)"},".marker-target":{"d":"M 10 0 L 0 5 L 10 10 z"},".connection":{"stroke":"black"}}}]
我只需要创建一个方法将这段代码放入其中以获取所有键值对:
//Create a JsonFactory instance
JsonFactory factory = new JsonFactory();
//Create a JsonParser instance to read from file c:\\text.json
JsonParser jParser = factory.createJsonParser(new File("c:\\text.json"));
/*Create an ObjectMapper instance to provide a pointer
*to root node of the tree after reading the JSON
*/
ObjectMapper mapper = new ObjectMapper(factory);
//Create tree from JSON
JsonNode rootNode = mapper.readTree(jParser);
Iterator<Map.Entry<String,JsonNode>> fieldsIterator = rootNode.getFields();
while (fieldsIterator.hasNext()) {
Map.Entry<String,JsonNode> field = fieldsIterator.next();
System.out.println("Key: " + field.getKey() + "\tValue:" + field.getValue());
}
请问我该怎么做?
最佳答案
您应该使用 Jackson2 而不是 Jackson1。正如错误消息所指出的,Jackson1 的 JsonNode
确实没有此 fields()
方法,而 Jackson2's version does .
在 Jackson1 中,您必须执行以下操作:
Iterator<String> fieldNameIterator = rootNode.getFieldNames();
while (fieldNameIterator.hasNext()) {
String fieldName = fieldNameIterator.next();
JsonNode fieldValue = rootNode.getFieldValue(fieldName);
System.out.println("Key: " + fieldName + "\tValue:" + fieldValue);
}
关于java - 如何创建一个 Java 方法来解析一个大的 JSON 文件,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/41461821/
最近开始学习MongoDB。今天老师教了我们 mongoexport 命令。在练习时,我遇到了一个典型的问题,包括教练在内的其他同学都没有遇到过。我在我的 Windows 10 机器上使用 Mongo
我是 JSON Schema 的新手,读过什么是 JSON Schema 等等。但我不知道如何将 JSON Schema 链接到 JSON 以针对该 JSON Schema 进行验证。谁能解释一下?
在 xml 中,我可以在另一个 xml 文件中包含一个文件并使用它。如果您的软件从 xml 获取配置文件但没有任何方法来分离配置,如 apache/ngnix(nginx.conf - site-av
我有一个 JSON 对象,其中包含一个本身是 JSON 对象的字符串。我如何反序列化它? 我希望能够做类似的事情: #[derive(Deserialize)] struct B { c: S
考虑以下 JSON { "a": "{\"b\": 12, \"c\": \"test\"}" } 我想定义一个泛型读取 Reads[Outer[T]]对于这种序列化的 Json import
关闭。这个问题不满足Stack Overflow guidelines .它目前不接受答案。 想改善这个问题吗?更新问题,使其成为 on-topic对于堆栈溢出。 11 个月前关闭。 Improve
我的旧项目在 MySQL 中有 Standard JSON 格式的数据。 对于我在 JS (Node.js) 和 DynamoDB 中的全新项目,关于 Standard JSON格式: 是否建议将其转
JSON 值字符串、数字、true、false、null 是否是有效的 JSON? 即,是 true 一个有效的 JSON 文档?还是必须是数组/对象? 一些验证器接受这个(例如 http://jso
我有一个 JSON 字符串,其中一个字段是文本字段。这个文本字段可以包含用户在 UI 中输入的文本,如果他们输入的文本是 JSON 文本,也许是为了说明一些编码,我需要对他们的文本进行编码,以便它不会
我正在通过 IBM MQ 调用处理数据,当由 ColdFusion 10 (10,0,11,285437) 序列化时,0 将作为 +0.0 返回,它会导致无效的 JSON并且无法反序列化。 stPol
我正在从三个数组中生成一个散列,然后尝试构建一个 json。我通过 json object has array 成功了。 require 'json' A = [['A1', 'A2', 'A3'],
我从 API 接收 JSON,响应可以是 30 种类型之一。每种类型都有一组唯一的字段,但所有响应都有一个字段 type 说明它是哪种类型。 我的方法是使用serde .我为每种响应类型创建一个结构并
我正在下载一个 JSON 文件,我已将其检查为带有“https://jsonlint.com”的有效 JSON 到文档目录。然后我打开文件并再次检查,结果显示为无效的 JSON。这怎么可能????这是
我正在尝试根据从 API 接收到的数据动态创建一个 JSON 对象。 收到的示例数据:将数据解码到下面给出的 CiItems 结构中 { "class_name": "test", "
我想从字符串转换为对象。 来自 {"key1": "{\n \"key2\": \"value2\",\n \"key3\": {\n \"key4\": \"value4\"\n }\n
目前我正在使用以下代码将嵌套的 json 转换为扁平化的 json: import ( "fmt" "github.com/nytlabs/gojsonexplode" ) func
我有一个使用来自第三方 API 的数据的应用程序。我需要将 json 解码为一个结构,这需要该结构具有“传入”json 字段的 json 标签。传出的 json 字段具有不同的命名约定,因此我需要不同
我想使用 JSON 架构来验证某些值。我有两个对象,称它们为 trackedItems 和 trackedItemGroups。 trackedItemGroups 是组名称和 trackedItem
考虑以下案例类模式, case class Y (a: String, b: String) case class X (dummy: String, b: Y) 字段b是可选的,我的一些数据集没有字
我正在存储 cat ~/path/to/file/blah | 的输出jq tojson 在一个变量中,稍后在带有 JSON 内容的 curl POST 中使用。它运作良好,但它删除了所有换行符。我知
我是一名优秀的程序员,十分优秀!