在Jackson
中,您可以将整个JSON
载荷读取为JsonNode
并迭代所有属性以检查给定条件。 如果满足条件,则可以删除给定字段。 为此,您需要实现递归方法。 请参阅以下示例:
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.ObjectNode;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.Map;
import java.util.Objects;
import java.util.function.Predicate;
public class JsonRemoveSomeFieldsApp {
public static void main(String[] args) throws IOException {
File jsonFile = new File("./resource/test.json").getAbsoluteFile();
ObjectMapper mapper = new ObjectMapper();
mapper.enable(SerializationFeature.INDENT_OUTPUT);
JsonNode root = mapper.readTree(jsonFile);
JsonCleaner jsonCleaner = new JsonCleaner(root, (node) -> node.isNumber() && node.numberValue().intValue() == -1);
JsonNode result = jsonCleaner.removeAll();
mapper.writeValue(System.out, result);
}
}
class JsonCleaner {
private final JsonNode root;
private final Predicate<JsonNode> toRemoveCondition;
JsonCleaner(JsonNode node, Predicate<JsonNode> toRemoveCondition) {
this.root = Objects.requireNonNull(node);
this.toRemoveCondition = Objects.requireNonNull(toRemoveCondition);
}
public JsonNode removeAll() {
process(root);
return root;
}
private void process(JsonNode node) {
if (node.isObject()) {
ObjectNode object = (ObjectNode) node;
Iterator<Map.Entry<String, JsonNode>> fields = object.fields();
while (fields.hasNext()) {
Map.Entry<String, JsonNode> field = fields.next();
JsonNode valueToCheck = field.getValue();
if (valueToCheck.isContainerNode()) {
process(valueToCheck);
} else if (toRemoveCondition.test(valueToCheck)) {
fields.remove();
}
}
} else if (node.isArray()) {
ArrayNode array = (ArrayNode) node;
array.elements().forEachRemaining(this::process);
}
}
}
对于下面的 JSON
负载:
{
"name": "Head",
"missed": -1,
"covered": -1,
"children": [
{
"name": "project1",
"missed": -1,
"covered": -1,
"children": [
{
"name": "project1",
"missed": 10,
"covered": 11
}
]
},
{
"name": "project1",
"missed": -1,
"covered": 12,
"children": [
{
"name": "project1",
"missed": 10,
"covered": -1
}
]
}
]
}
上面的代码输出:
{
"name" : "Head",
"children" : [ {
"name" : "project1",
"children" : [ {
"name" : "project1",
"missed" : 10,
"covered" : 11
} ]
}, {
"name" : "project1",
"covered" : 12,
"children" : [ {
"name" : "project1",
"missed" : 10
} ]
} ]
}
参见:
Map
这样的类型绑定,因为无法保证在写入时得到相同的结构。使用JsonNode
或Jackson用于JSON树表示的任何内容,递归地遍历JSON对象和数组,找到要删除的元素,然后简单地将它们全部删除即可。就是这样。 - terrorrussia-keeps-killing