使用GSON读取和写入数据 [英] read and write data with GSON

问题描述

我正在努力寻找一个关于如何在我的android应用程序中使用GSON读取和写入数据的好例子。有人可以指给我看一个好例子吗？

我的教授给出了这个例子来写作：

  Vector v = new Vector（10.0f，20.0f）; 
 Gson gson = new Gson（）; 
 String s = gson.toJson（v）; 
  

我会如何将其保存到文件中？

> String filename =myfile.txt;

Vector v = new Vector（10.0f，20.0f）;
Gson gson = new Gson（）;
String s = gson.toJson（v）;

FileOutputStream outputStream;

尝试{
outputStream = openFileOutput（filename，Context.MODE_PRIVATE）;
outputStream.write（s.getBytes（））;
outputStream.close（）;
} catch（Exception e）{
e.printStackTrace（）;
}

如何读回：

  FileInputStream fis = context.openFileInput（myfile.txt，Context.MODE_PRIVATE）; 
 InputStreamReader isr = new InputStreamReader（fis）; 
 BufferedReader bufferedReader = new BufferedReader（isr）; 
 StringBuilder sb = new StringBuilder（）; 
字符串行; （（line = bufferedReader.readLine（））！= null）{
 sb.append（line）; 
 while 
} 
 
 String json = sb.toString（）; 
 Gson gson = new Gson（）; 
 Vector v = gson.fromJson（json，Vector.class）; 
  

I am struggling to find a good example on how to read and write data in my android app using GSON. Could someone please show me or point me to a good example? I am using this for data persistence between activities.

My professor gave this example to for writing:

Vector v = new Vector(10.0f, 20.0f);
Gson gson = new Gson();
String s = gson.toJson(v);

How would I go about saving that to a file?

解决方案

How to save your JSON into a file on internal storage:

String filename = "myfile.txt";

Vector v = new Vector(10.0f, 20.0f);
Gson gson = new Gson();
String s = gson.toJson(v);

FileOutputStream outputStream;

try {
  outputStream = openFileOutput(filename, Context.MODE_PRIVATE);
  outputStream.write(s.getBytes());
  outputStream.close();
} catch (Exception e) {
  e.printStackTrace();
}

How to read it back:

 FileInputStream fis = context.openFileInput("myfile.txt", Context.MODE_PRIVATE);
 InputStreamReader isr = new InputStreamReader(fis);
 BufferedReader bufferedReader = new BufferedReader(isr);
 StringBuilder sb = new StringBuilder();
 String line;
 while ((line = bufferedReader.readLine()) != null) {
     sb.append(line);
 }

 String json = sb.toString();
 Gson gson = new Gson();
 Vector v = gson.fromJson(json, Vector.class);

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