使用 json 节点解析 JSON 字符串

Question

我有一个普通的 json 字符串要解析：

"name":"Jake",
"salary":3000,
"phones":[{"phoneType":"cell","phoneNumber":"111-111-111"},
            {"phoneType":"work","phoneNumber":"222-222-222"}],
"taskIds":[11,22,33],
"address":{"street":"101 Blue Dr","city":"White Smoke"}}

我想从此 json 创建对象列表并将其保存到数据库。这是我的模型：

public class Model {
    private long id;
    private String nodeName;
    private String nodeType;
    private String nodeValue;
    private Model parent; 
}

这是我尝试过的完整的 JAVA 代码：

public class TreeModelParser {

    static List<Model> models = new ArrayList<Model>();
    static Model model;
    static int id = 0;
    static boolean first = true;
    static int nbr = 0;
    static int nbr2 = 0;
    static List<JsonNode> parsedNodes;

    public static void main(String[] args) throws IOException {
        String inputJson = "{\"name\":\"Jake\",\"salary\":3000,\"phones\":"
                + "[{\"phoneType\":\"cell\",\"phoneNumber\":\"111-111-111\"},"
                + "{\"phoneType\":\"work\",\"phoneNumber\":\"222-222-222\"}]," + "\"taskIds\":[11,22,33],"
                + "\"address\":{\"street\":\"101 Blue Dr\",\"city\":\"White Smoke\"}}";
        ObjectMapper objectMapper = new ObjectMapper();
        JsonNode rootNode = objectMapper.readTree(inputJson);
        models = new ArrayList<Model>();
        model = new Model();
        traverse(rootNode, 1);
        for (Model mod : models) {
            System.out.println(
                    mod.getId() + "-" + mod.getNodeName() + "-" + mod.getNodeType() + "-" + mod.getNodeValue());
        }

    }

    private static void traverse(JsonNode node, int level) {
        if (node.getNodeType() == JsonNodeType.ARRAY) {
            traverseArray(node, level);
        } else if (node.getNodeType() == JsonNodeType.OBJECT) {
            traverseObject(node, level);

        } else {
            throw new RuntimeException("Not yet implemented");
        }
    }

    private static void traverseObject(JsonNode node, int level) {
        Iterator<String> fieldNames = node.fieldNames();
        List<String> lst = getListFromIterator(fieldNames);
        for (String fieldName : lst) {
            JsonNode childNode = node.get(fieldName);
            printNode(childNode, fieldName, level);
            if (traversable(childNode)) {
                traverse(childNode, level + 1);
            }
        }
    }

    private static void traverseArray(JsonNode node, int level) {
        for (JsonNode jsonArrayNode : node) {
            printNode(jsonArrayNode, "arrayElement", level);

            if (traversable(jsonArrayNode)) {
                traverse(jsonArrayNode, level + 1);
            }
        }
    }

    private static boolean traversable(JsonNode node) {
        return node.getNodeType() == JsonNodeType.OBJECT || node.getNodeType() == JsonNodeType.ARRAY;
    }

    private static void printNode(JsonNode node, String keyName, int level) {
        model = new Model();
        id++;
        model.setId(id);
        model.setNodeName(keyName);

        if (node.getNodeType().equals(JsonNodeType.ARRAY)) {
            model.setNodeType("ARRAY");
        } else if (node.getNodeType().equals(JsonNodeType.STRING)) {
            model.setNodeType("STRING");
        } else if (node.getNodeType().equals(JsonNodeType.NUMBER)) {
            model.setNodeType("NUMBER");
        } else if (node.getNodeType().equals(JsonNodeType.OBJECT)) {
            model.setNodeType("OBJECT");
        } else if (node.getNodeType().equals(JsonNodeType.BOOLEAN)) {
            model.setNodeType("BOOLEAN");
        }
        if (traversable(node)) {

        } else {
            Object value = null;
            if (node.isTextual()) {
                value = node.textValue();
                model.setNodeValue((String) value);
            } else if (node.isNumber()) {
                value = node.numberValue();
                model.setNodeValue((Number) value + "");
            }

        }
        models.add(model);
    }

    public static List<String> getListFromIterator(Iterator<String> iterator) {
        List<String> list = new ArrayList<>();
        iterator.forEachRemaining(list::add);
        return list;
    }

}

当我运行这段代码时，我几乎得到了我想要的：

1-name-STRING-Jake-null
2-salary-NUMBER-3000-null
3-phones-ARRAY-null-null
4-arrayElement-OBJECT-null-null
5-phoneType-STRING-cell-null
6-phoneNumber-STRING-111-111-111-null
7-arrayElement-OBJECT-null-null
8-phoneType-STRING-work-null
9-phoneNumber-STRING-222-222-222-null
10-taskIds-ARRAY-null-null
11-arrayElement-NUMBER-11-null
12-arrayElement-NUMBER-22-null
13-arrayElement-NUMBER-33-null
14-address-OBJECT-null-null
15-street-STRING-101 Blue Dr-null
16-city-STRING-White Smoke-null

问题是我不知道如何放置每个对象（节点）的父级。我真的找不到任何解决方案。

Answer 1

如果我们将List<Model> models 和Model model 属性移动到方法并在每次需要时传递它们会容易得多。我们可以传递Model parent 参数，而不是传递不需要的level，这将是给定节点的父对象：

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.node.JsonNodeType;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

public class JsonModelApp {

    public static void main(String[] args) throws Exception {
        String inputJson = "{\"name\":\"Jake\",\"salary\":3000,\"phones\":"
                + "[{\"phoneType\":\"cell\",\"phoneNumber\":\"111-111-111\"},"
                + "{\"phoneType\":\"work\",\"phoneNumber\":\"222-222-222\"}]," + "\"taskIds\":[11,22,33],"
                + "\"address\":{\"street\":\"101 Blue Dr\",\"city\":\"White Smoke\"}}";
        ObjectMapper objectMapper = new ObjectMapper();
        JsonNode rootNode = objectMapper.readTree(inputJson);

        List<Model> models = new TreeModelParser().traverse(rootNode);
        for (Model mod : models) {
            System.out.println(mod + " => Parent: " + mod.getParent());
        }
    }
}

class TreeModelParser {

    private int id = 0;

    public List<Model> traverse(JsonNode root) {
        Model parent = new Model();
        parent.setNodeName("ROOT");

        List<Model> models = new ArrayList<>();
        traverse(models, root, parent);
        return models;
    }

    private void traverse(List<Model> models, JsonNode node, Model parent) {
        if (node.getNodeType() == JsonNodeType.ARRAY) {
            traverseArray(models, node, parent);
        } else if (node.getNodeType() == JsonNodeType.OBJECT) {
            traverseObject(models, node, parent);

        } else {
            throw new RuntimeException("Not yet implemented");
        }
    }

    private void traverseObject(List<Model> models, JsonNode node, Model parent) {
        Iterator<String> fieldNames = node.fieldNames();
        List<String> lst = getListFromIterator(fieldNames);
        for (String fieldName : lst) {
            JsonNode childNode = node.get(fieldName);
            Model model = createModel(childNode, fieldName, parent);
            models.add(model);
            if (traversable(childNode)) {
                traverse(models, childNode, model);
            }
        }
    }

    private void traverseArray(List<Model> models, JsonNode node, Model parent) {
        for (JsonNode jsonArrayNode : node) {
            Model model = createModel(jsonArrayNode, "arrayElement", parent);
            models.add(model);
            if (traversable(jsonArrayNode)) {
                traverse(models, jsonArrayNode, model);
            }
        }
    }

    private static boolean traversable(JsonNode node) {
        return node.getNodeType() == JsonNodeType.OBJECT || node.getNodeType() == JsonNodeType.ARRAY;
    }

    private Model createModel(JsonNode node, String keyName, Model parent) {
        Model model = new Model();
        model.setId(++id);
        model.setNodeName(keyName);
        model.setParent(parent);

        if (node.getNodeType().equals(JsonNodeType.ARRAY)) {
            model.setNodeType("ARRAY");
        } else if (node.getNodeType().equals(JsonNodeType.STRING)) {
            model.setNodeType("STRING");
        } else if (node.getNodeType().equals(JsonNodeType.NUMBER)) {
            model.setNodeType("NUMBER");
        } else if (node.getNodeType().equals(JsonNodeType.OBJECT)) {
            model.setNodeType("OBJECT");
        } else if (node.getNodeType().equals(JsonNodeType.BOOLEAN)) {
            model.setNodeType("BOOLEAN");
        }
        if (!traversable(node)) {
            Object value;
            if (node.isTextual()) {
                value = node.textValue();
                model.setNodeValue((String) value);
            } else if (node.isNumber()) {
                value = node.numberValue();
                model.setNodeValue(value + "");
            }

        }

        return model;
    }

    private static List<String> getListFromIterator(Iterator<String> iterator) {
        List<String> list = new ArrayList<>();
        iterator.forEachRemaining(list::add);
        return list;
    }

}

class Model {
    private long id;
    private String nodeName;
    private String nodeType;
    private String nodeValue;
    private Model parent;

    public long getId() {
        return id;
    }

    public void setId(long id) {
        this.id = id;
    }

    public String getNodeName() {
        return nodeName;
    }

    public void setNodeName(String nodeName) {
        this.nodeName = nodeName;
    }

    public String getNodeType() {
        return nodeType;
    }

    public void setNodeType(String nodeType) {
        this.nodeType = nodeType;
    }

    public String getNodeValue() {
        return nodeValue;
    }

    public void setNodeValue(String nodeValue) {
        this.nodeValue = nodeValue;
    }

    public Model getParent() {
        return parent;
    }

    public void setParent(Model parent) {
        this.parent = parent;
    }

    @Override
    public String toString() {
        final StringBuilder sb = new StringBuilder("Model{");
        sb.append("id=").append(id);
        sb.append(", nodeName='").append(nodeName).append('\'');
        sb.append(", nodeType='").append(nodeType).append('\'');
        if (nodeValue != null) {
            sb.append(", nodeValue='").append(nodeValue).append('\'');
        }
        sb.append('}');
        return sb.toString();
    }
}

上面的代码打印：

Model{id=1, nodeName='name', nodeType='STRING', nodeValue='Jake'} => Parent: Model{id=0, nodeName='ROOT', nodeType='null'}
Model{id=2, nodeName='salary', nodeType='NUMBER', nodeValue='3000'} => Parent: Model{id=0, nodeName='ROOT', nodeType='null'}
Model{id=3, nodeName='phones', nodeType='ARRAY'} => Parent: Model{id=0, nodeName='ROOT', nodeType='null'}
Model{id=4, nodeName='arrayElement', nodeType='OBJECT'} => Parent: Model{id=3, nodeName='phones', nodeType='ARRAY'}
Model{id=5, nodeName='phoneType', nodeType='STRING', nodeValue='cell'} => Parent: Model{id=4, nodeName='arrayElement', nodeType='OBJECT'}
Model{id=6, nodeName='phoneNumber', nodeType='STRING', nodeValue='111-111-111'} => Parent: Model{id=4, nodeName='arrayElement', nodeType='OBJECT'}
Model{id=7, nodeName='arrayElement', nodeType='OBJECT'} => Parent: Model{id=3, nodeName='phones', nodeType='ARRAY'}
Model{id=8, nodeName='phoneType', nodeType='STRING', nodeValue='work'} => Parent: Model{id=7, nodeName='arrayElement', nodeType='OBJECT'}
Model{id=9, nodeName='phoneNumber', nodeType='STRING', nodeValue='222-222-222'} => Parent: Model{id=7, nodeName='arrayElement', nodeType='OBJECT'}
Model{id=10, nodeName='taskIds', nodeType='ARRAY'} => Parent: Model{id=0, nodeName='ROOT', nodeType='null'}
Model{id=11, nodeName='arrayElement', nodeType='NUMBER', nodeValue='11'} => Parent: Model{id=10, nodeName='taskIds', nodeType='ARRAY'}
Model{id=12, nodeName='arrayElement', nodeType='NUMBER', nodeValue='22'} => Parent: Model{id=10, nodeName='taskIds', nodeType='ARRAY'}
Model{id=13, nodeName='arrayElement', nodeType='NUMBER', nodeValue='33'} => Parent: Model{id=10, nodeName='taskIds', nodeType='ARRAY'}
Model{id=14, nodeName='address', nodeType='OBJECT'} => Parent: Model{id=0, nodeName='ROOT', nodeType='null'}
Model{id=15, nodeName='street', nodeType='STRING', nodeValue='101 Blue Dr'} => Parent: Model{id=14, nodeName='address', nodeType='OBJECT'}
Model{id=16, nodeName='city', nodeType='STRING', nodeValue='White Smoke'} => Parent: Model{id=14, nodeName='address', nodeType='OBJECT'}