1. String --> InputStream

public static InputStream String2InputStream(String str) throws IOException{
   ByteArrayInputStream stream = new ByteArrayInputStream(str.getBytes());
   return stream;
}
　2. InputStream --> String

public static String inputStream2String(InputStream is) throws IOException{
   ByteArrayOutputStream baos = new ByteArrayOutputStream();
   int i=-1;
   while((i=is.read())!=-1){
        baos.write(i);
   }
   return baos.toString();
}

1. String --> InputStream

public static InputStream String2InputStream(String str) throws IOException{
   ByteArrayInputStream stream = new ByteArrayInputStream(str.getBytes());
   return stream;
}
　2. InputStream --> String

public static String inputStream2String(InputStream is) throws IOException{
   ByteArrayOutputStream baos = new ByteArrayOutputStream();
   int i=-1;
   while((i=is.read())!=-1){
        baos.write(i);
   }
   return baos.toString();
}