java - Gson 错误？如果写入文件则忽略 PrettyPrinting

Question

写入文件时如何使用 pretty-print ？

package tests;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.stream.JsonWriter;

public class Try06 {

    public static class V {
        double x, y;
    }


    public static void main(String[] args) throws IOException {

        GsonBuilder gb = new GsonBuilder();

        gb = gb
         .setPrettyPrinting()
         .setVersion(1.0)


         ;

        Gson gson0 = gb.create();

        File file = new File("D:\\test.json");

        System.out.println(gson0.toJson(new V()));

        JsonWriter writer = new JsonWriter(new OutputStreamWriter(new FileOutputStream(file)));
        gson0.toJson(new V(), V.class, writer);
        writer.flush();
        writer.close();



    }
}

我还注意到，如果不刷新该文件就是空的。退出时是否应该刷新？

Answer 1

显式设置非空字符串缩进有助于:

Gson gson = new GsonBuilder().setPrettyPrinting().create();
JsonWriter writer = new JsonWriter(new FileWriter(fileOut));
writer.setIndent("  "); // <-- without this the file is written without line-breaks and indents
gson.toJson(object, type, writer);

还没来得及查Gson源码，可能还有别的办法解决。