//1.字符串转inputstream        String str="aaaaa";        InputStream in = new ByteArrayInputStream(str.getBytes());                //2.inputstream转字符串        String result = readFromInputStream(inputStream);//调用处        //将输入流InputStream变为String            public String readFromInputStream(InputStream in) throws IOException {                ByteArrayOutputStream baos = new ByteArrayOutputStream();                byte[] buffer = new byte[1024];                int len = -1;                while ((len = in.read(buffer)) != -1) {                    baos.write(buffer, 0, len);                }                baos.close();                in.close();                                byte[] lens = baos.toByteArray();                String result = new String(lens,"UTF-8");//内容乱码处理                                return result;                        }        //3.String写入OutputStream中        OutputStream out = System.out;          out.write(str.getBytes());                 //4.outputStream转string        ByteArrayOutputStream baos = new ByteArrayOutputStream();          //向OutPutStream中写入，如 message.writeTo(baos);         baos.write(str.getBytes());        String str1= baos.toString();