Java 如何使用JsonWriter在Gson中写入数据,而不重写/删除以前存储的数据
因此,在我运行代码之前,这里是example.json:Java 如何使用JsonWriter在Gson中写入数据,而不重写/删除以前存储的数据,java,json,gson,writing,Java,Json,Gson,Writing,因此,在我运行代码之前,这里是example.json: { "example1": 5 } {"example2":13} 当我执行此代码时: JsonWriter exampleWriter = new JsonWriter(new FileWriter(examplePath)); exampleWriter.beginObject(); exampleWriter.name("example2").value(13);
{
"example1": 5
}
{"example2":13}
当我执行此代码时:
JsonWriter exampleWriter = new JsonWriter(new FileWriter(examplePath));
exampleWriter.beginObject();
exampleWriter.name("example2").value(13);
exampleWriter.endObject();
exampleWriter.close();
然后example.json就会发生这种情况:
{
"example1": 5
}
{"example2":13}
我希望example.json包含example1和example2的数据,我该怎么做?试试看
JsonWriter exampleWriter=newJSONWriter(newFileWriter(examplePath,true)) 试试看
JsonWriter exampleWriter=newJSONWriter(newFileWriter(examplePath,true)) 您可以将整个
JSON
负载读取为JsonObject
并添加新属性。之后,您可以将其序列化回JSON
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
public class GsonApp {
public static void main(String[] args) throws IOException {
Path pathToJson = Paths.get("./resource/test.json");
Gson gson = new GsonBuilder().setPrettyPrinting().create();
try (BufferedReader reader = Files.newBufferedReader(pathToJson);
BufferedWriter writer = Files.newBufferedWriter(pathToJson, StandardOpenOption.WRITE)) {
JsonObject root = gson.fromJson(reader, JsonObject.class);
root.addProperty("example2", 13);
gson.toJson(root, writer);
}
}
}
上述代码生成:
{
"example1": 5,
"example2": 13
}
另见:
JSON
负载读取为JsonObject
并添加新属性。之后,您可以将其序列化回JSON
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.StandardOpenOption;
public class GsonApp {
public static void main(String[] args) throws IOException {
Path pathToJson = Paths.get("./resource/test.json");
Gson gson = new GsonBuilder().setPrettyPrinting().create();
try (BufferedReader reader = Files.newBufferedReader(pathToJson);
BufferedWriter writer = Files.newBufferedWriter(pathToJson, StandardOpenOption.WRITE)) {
JsonObject root = gson.fromJson(reader, JsonObject.class);
root.addProperty("example2", 13);
gson.toJson(root, writer);
}
}
}
上述代码生成:
{
"example1": 5,
"example2": 13
}
另见: