Question

我有服务器在Android中发送bmp文件和客户端，我尝试保存我收到的数据。我使用以下代码将数据保存在文件中：

...
byte[] Rbuffer = new byte[2000];
dis.read(Rbuffer);

try {
    writeSDCard.writeToSDFile(Rbuffer);
    } catch (Exception e) {
    Log.e("TCP", "S: Error at file write", e);

    } finally {
    Log.e("Writer", "S: Is it written?");
    }
...

 void writeToSDFile(byte[] inputMsg){

    // Find the root of the external storage.
    // See http://developer.android.com/guide/topics/data/data-  storage.html#filesExternal

    File root = android.os.Environment.getExternalStorageDirectory();

    File dir = new File (root.getAbsolutePath() + "/download");
    if (!(dir.exists())) {
         dir.mkdirs();
     }
    Log.d("WriteSDCard", "Start writing");

    File file = new File(dir, "myData.txt");

    try {
   // Start writing in the file without overwriting previous data ( true input)
        Log.d("WriteSDCard", "Start writing 1");
        FileOutputStream f = new FileOutputStream(file, true);
        PrintWriter ps = new PrintWriter(f);
//      PrintStream ps = new PrintStream(f);
        ps.print(inputMsg);
        ps.flush();
        ps.close();
        Log.d("WriteSDCard", "Start writing 2");
        f.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
        Log.i(TAG, "******* File not found. Did you" +
                " add a WRITE_EXTERNAL_STORAGE permission to the   manifest?");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

但是在输出中我收到了对象ids

e.g。 [B @ 23fgfgre [B @ eft908eh ...

（其中[表示数组.B表示字节。@将类型与ID分开。十六进制数字是对象ID或哈希码。）

即使使用＆＃34; PrintStream＆＃34;我也会收到同样的结果。而不是＆＃34; PrintWriter＆＃34; ...

如何保存实际输出？

Answer 1

尝试：

FileOutputStream f = new FileOutputStream(file, true);
f.write(inputMsg);
f.close();

Answer 2

PrintWriter和PrintStream名称中的“print”一词应该会提示您生成文本。如果你仔细阅读文档，那就明确说明了。

https://docs.oracle.com/javase/7/docs/api/java/io/PrintWriter.html#print(java.lang.Object)

具体而言，您明确使用的print(Object obj) PrintWriter重载文档

打印一个对象。 String.valueOf（Object）方法生成的字符串根据平台的默认字符编码转换为字节，这些字节的写入方式与write（int）方法完全相同。

显然，这不是你想要的。您有一个字节数组，并且您希望将这些字节写入文件，就像它们一样。所以，忘掉PrintWriter和PrintStream。相反，做这样的事情：

BufferedOutputStream bos = new BufferedOutputStream(f);
bos.write(inputMsg);
//bos.flush(); stop. always. flushing. close. does. that.
bos.close();

在java中保存收到的数据

2 个答案: