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我正在从本地目录读取 JSON 提要，并希望在将其保存到其他文件之前对其进行修改。

这是JSON提要的在线版本

结构如下：

[
  {
    "title":"chapter Title", 
    "arr":[
            {
             "title":"SubChapter Title",        
             "arr":[
                     [
                      "Sub Sub Chapter Title", 
                       272, 
                       1124, 
                       10550, 
                       11044,
                       -11172,
                       ......
                     ],
                     ........
             ............
       ...........
.......

我需要在现有JSON文件中添加问题标题和问题编号，例如：

[
  {
    "title":"chapter Title", 
    "arr":[
            {
             "title":"SubChapter Title",        
             "arr":[
                     [
                      "Sub Sub Chapter Title", 
                       272, "This is a title",
                       1124, "This is another title",
                       10550, ".....",
                       11044, "......",
                       -11172, "......",
                       ......
                     ],
                     ........
             ............
       ...........
.......

我已经将问题标题映射到问题 No 以添加它们。我阅读了提要字符串并找出problem No用problem No. problem Title这是我的尝试代码：

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.HashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import java.util.regex.PatternSyntaxException;

import com.google.gson.stream.JsonReader;

public class JacksonStreamAPIExample {

    static String PROBLEM_LIST_FILE_PATH = "F:\\problemList.txt";
    static String COMPETITIVE_PROGRAMMING_BOOK_PATH = "F:\\competitive_programming_edition_3.json";
    static String TARGET_PATH = "F:\\target.json";

    static HashMap<Integer, String> problems = new HashMap<Integer, String>();

    public static void main(String[] args) {
        // Mapping problem No with problem Title
        InputStream is = null;
        try {
            is = new FileInputStream(PROBLEM_LIST_FILE_PATH);
        } catch (FileNotFoundException e1) {

        }
        JsonReader reader = null;
        try {
            reader = new JsonReader(new InputStreamReader(is, "UTF-8"));
        } catch (UnsupportedEncodingException e1) {

        }
        try {
            reader.beginArray();
            while (reader.hasNext()) {
                reader.beginArray();
                reader.skipValue();
                problems.put(reader.nextInt(), reader.nextString());
                reader.skipValue();
                while (reader.hasNext())
                    reader.skipValue();
                reader.endArray();
            }
            reader.endArray();
            reader.close();
        } catch (IOException e) {
        }

        // Reading and modifying
        InputStream inputStream = null;
        try {
            inputStream = new FileInputStream(COMPETITIVE_PROGRAMMING_BOOK_PATH);
        } catch (FileNotFoundException e) {
            System.out.println("file not found!");
        }
        InputStreamReader isr = null;
        isr = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
        BufferedReader read = new BufferedReader(isr, 8);
        StringBuilder sb = new StringBuilder();
        String line = null;
        try {
            while ((line = read.readLine()) != null) {
                sb.append(line + "\n");
            }
        } catch (IOException e) {
        }
        try {
            inputStream.close();
        } catch (IOException e) {

        }
        String jsonString = sb.toString();

        try {
            String regex = ", (-?\\d+)";
            Pattern myPattern = Pattern.compile(regex);
            Matcher regexMatcher = myPattern.matcher(jsonString);

            while (regexMatcher.find()) {
                for (int i = 1; i <= regexMatcher.groupCount(); i++) {
                 System.out.println("I want to add " + problems.get(Math.abs(Integer.parseInt(regexMatcher.group(i)))) + " after " + regexMatcher.group(i) + " in jsonString and write it in target file.");
                }
            }
        } catch (PatternSyntaxException ex) {

        }
        Path path = Paths.get(TARGET_PATH);
        try {
            Files.write(path, jsonString.getBytes(StandardCharsets.UTF_8));
        } catch (IOException e) {

        }
    }
}

一切正常。只有在问题 No 之后替换/添加问题标题不起作用。我怎样才能完成这项工作？

4

1 回答 1

0

@Dave Newton 是对的。你应该JSON通过创建一个JSONWriter对象来做到这一点。解析JSONwithJsonReader实例并按顺序添加它们JsonWriter。另外problemTitle从您已经完成的映射中添加。

幸运的是，我已经代表您完成了您的任务。希望稍微修改一下就可以了。

package demo;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;

import java.util.HashMap;

import com.google.gson.stream.JsonReader;
import com.google.gson.stream.JsonWriter;

public class JacksonStreamAPIExample {

    static String PROBLEM_LIST_FILE_PATH = "F:\\kaidul.txt";
    static String COMPETITIVE_PROGRAMMING_BOOK_PATH = "F:\\competitive_programming_edition_3.json";
    static String TARGET_PATH = "F:\\test.json";

    static HashMap<Integer, String> problems = new HashMap<Integer, String>();

    public static void main(String[] args) {
        // Mapping problem No with problem Title
        InputStream is = null;
        try {
            is = new FileInputStream(PROBLEM_LIST_FILE_PATH);
        } catch (FileNotFoundException e) {

        }
        try {
            JsonReader reader  = new JsonReader(new InputStreamReader(is, StandardCharsets.UTF_8));
            reader.beginArray();
            while (reader.hasNext()) {
                reader.beginArray();
                reader.skipValue();
                problems.put(reader.nextInt(), reader.nextString());
                reader.skipValue();
                while (reader.hasNext())
                    reader.skipValue();
                reader.endArray();
            }
            reader.endArray();
            reader.close();
        } catch (IOException e) {
        }

        // Reading and modifying
        JsonWriter writer = null;
        InputStream inputStream = null;
        try {
            inputStream = new FileInputStream(COMPETITIVE_PROGRAMMING_BOOK_PATH);

            JsonReader reader = new JsonReader(new InputStreamReader(
                    inputStream));
            writer = new JsonWriter(new FileWriter(TARGET_PATH));

            reader.beginArray(); // array #1
            writer.beginArray();
            while (reader.hasNext()) {
                reader.beginObject(); // object #2
                writer.beginObject();
                while (reader.hasNext()) {
                    reader.skipValue();
                    writer.name("title").value(reader.nextString());
                    reader.skipValue();
                    writer.name("arr");
                    reader.beginArray(); // array #3
                    writer.beginArray();
                    while (reader.hasNext()) {
                        reader.beginObject(); // object #4
                        writer.beginObject();
                        while (reader.hasNext()) {
                            reader.skipValue();
                            writer.name("title").value(reader.nextString());
                            reader.skipValue();
                            writer.name("arr");
                            reader.beginArray(); // array #5
                            writer.beginArray();
                            while (reader.hasNext()) {
                                reader.beginArray(); // array #6
                                writer.beginArray();
                                writer.value(reader.nextString());
                                while (reader.hasNext()) {
                                    int problemNo = reader.nextInt();
                                    writer.value(problemNo);
                                    writer.value(problems.get(Math.abs(problemNo))); // additional problemTitle
                                }
                                reader.endArray(); // array #6
                                writer.endArray();
                            }
                            reader.endArray(); // array #5
                            writer.endArray();
                        }
                        reader.endObject(); // object #4
                        writer.endObject();
                    }
                    reader.endArray(); // array #3
                    writer.endArray();
                }
                reader.endObject(); // object #2
                writer.endObject();
            }
            reader.endArray(); // array #1
            writer.endArray();
            reader.close();
            writer.close();
        } catch (IOException e) {
            // nothing
        } finally {
            if (inputStream != null) {
                try {
                    inputStream.close();
                } catch (IOException e) {
                    // nothing
                }
            }
        }
    }
}
于 2013-08-14T21:51:51.670 回答