Java 如何通过Jackson 2 JsonNode树遍历JSON?
这是一个有点沮丧的练习,因为我找不到这个问题的答案,这让我更加沮丧。所以我要在这里回答这个问题 我发现最难理解的是JsonNode没有任何Java 如何通过Jackson 2 JsonNode树遍历JSON?,java,json,jackson,Java,Json,Jackson,这是一个有点沮丧的练习,因为我找不到这个问题的答案,这让我更加沮丧。所以我要在这里回答这个问题 我发现最难理解的是JsonNode没有任何getName()或类似的方法,因为JSON是一种name:value数据类型,所以我不希望有这种方法。虽然我在解决这个问题后意识到数组不是name:value 见下面的答案 package treeWalker; import java.io.IOException; import java.util.ArrayList; import java.util
getName()
或类似的方法,因为JSON是一种name:value
数据类型,所以我不希望有这种方法。虽然我在解决这个问题后意识到数组不是name:value
见下面的答案
package treeWalker;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.common.collect.Lists;
public class TreeWalker
{
public JsonNode convertJSONToNode(String json) throws JsonProcessingException, IOException
{
ObjectMapper mapper = new ObjectMapper();
JsonNode jsonNode = mapper.readTree(json);
return jsonNode;
}
public void walkTree(JsonNode root)
{
walker(null, root);
}
private void walker(String nodename, JsonNode node)
{
String nameToPrint = nodename != null ? nodename : "must_be_root";
System.out.println("walker - node name: " + nameToPrint);
if (node.isObject())
{
Iterator<Map.Entry<String, JsonNode>> iterator = node.fields();
ArrayList<Map.Entry<String, JsonNode>> nodesList = Lists.newArrayList(iterator);
System.out.println("Walk Tree - root:" + node + ", elements keys:" + nodesList);
for (Map.Entry<String, JsonNode> nodEntry : nodesList)
{
String name = nodEntry.getKey();
JsonNode newNode = nodEntry.getValue();
// System.out.println(" entry - key: " + name + ", value:" + node);
walker(name, newNode);
}
}
else if (node.isArray())
{
Iterator<JsonNode> arrayItemsIterator = node.elements();
ArrayList<JsonNode> arrayItemsList = Lists.newArrayList(arrayItemsIterator);
for (JsonNode arrayNode : arrayItemsList)
{
walker("array item", arrayNode);
}
}
else
{
if (node.isValueNode())
{
System.out.println(" valueNode: " + node.asText());
}
else
{
System.out.println(" node some other type");
}
}
}
}
哦,还有build.gradle
:
apply plugin: 'java'
apply plugin: 'eclipse'
repositories {
mavenCentral()
}
dependencies {
compile 'org.slf4j:slf4j-api:1.7.5'
compile 'com.fasterxml.jackson.core:jackson-core:2.4.3'
compile 'com.fasterxml.jackson.core:jackson-databind:2.4.3'
compile 'com.fasterxml.jackson.core:jackson-annotations:2.4.3'
compile 'com.google.guava:guava:18.0'
testCompile "junit:junit:4.11"
}
谢谢我希望它不会使用com.google.common.collect.Lists。虽然这已经有点旧了,但它完全符合我对一段生产代码的需求(我自己也懒得去想,压力已经太大了)。只需将“walker”方法名称更改为“walk”,并修改“walkTree”方法签名,以执行额外的操作参数。你的原始作者是提到的来源!
apply plugin: 'java'
apply plugin: 'eclipse'
repositories {
mavenCentral()
}
dependencies {
compile 'org.slf4j:slf4j-api:1.7.5'
compile 'com.fasterxml.jackson.core:jackson-core:2.4.3'
compile 'com.fasterxml.jackson.core:jackson-databind:2.4.3'
compile 'com.fasterxml.jackson.core:jackson-annotations:2.4.3'
compile 'com.google.guava:guava:18.0'
testCompile "junit:junit:4.11"
}