InputStream和OutputStream與String之間的轉換

//1.字符串轉inputstream
        String str="aaaaa";
        InputStream in = new ByteArrayInputStream(str.getBytes());
        
        //2.inputstream轉字符串
        String result = readFromInputStream(inputStream);//調用處
        //將輸入流InputStream變為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");//內容亂碼處理
                
                return result;
            
            }
        //3.String寫入OutputStream中
        OutputStream out = System.out;  
        out.write(str.getBytes()); 
        
        //4.outputStream轉string
        ByteArrayOutputStream baos = new ByteArrayOutputStream();  
        //向OutPutStream中寫入，如 message.writeTo(baos); 
        baos.write(str.getBytes());
        String str1= baos.toString();