四、實例分析

同API一起下載的還有一個examples文件，里面有個最簡單的讀、寫程序，對其進行注釋，以增進了理。

（1）讀串口

?

1?	import?java.io.*;
2?	import?java.util.*;
3?	import?javax.comm.*;
4?	?
5?	public?class?SimpleRead?implements?Runnable,?SerialPortEventListener?{
6?	?
7?	?? ?static?CommPortIdentifier?portId;
8?	?? ?static?Enumeration?portList;//枚舉類
9?	?
10?	?? ?InputStream?inputStream;
11?	?? ?SerialPort?serialPort;
12?	?? ?Thread?readThread;
13?	?
14?	?? ?public?static?void?main(String[]?args)?{
15?	?
16?	?????? ?portList?=?CommPortIdentifier.getPortIdentifiers();/*不帶參數的getPortIdentifiers方法獲得一個枚舉對象，該對象又包含了系統中管理每個端口的CommPortIdentifier對象。注意這里的端口不僅僅是指串口，也包括并口。這個方法還可以帶參數。getPortIdentifiers(CommPort)獲得與已經被應用程序打開的端口相對應的CommPortIdentifier對象。?getPortIdentifier(String?portName)獲取指定端口名（比如“COM1”）的CommPortIdentifier對象。*/
17?	?
18?	?????? ?while?(portList.hasMoreElements())?{
19?	?????????? ?portId?=?(CommPortIdentifier)?portList.nextElement();
20?	?????????? ?if?(portId.getPortType()?==?CommPortIdentifier.PORT_SERIAL)/*getPortType方法返回端口類型*/?{
21?	?????????????? ?//?if?(portId.getName().equals("COM1"))/*?找Windows下的第一個串口*/?{
22?	?????????????? ?if?(portId.getName().equals("/dev/term/a"))/*找Unix-like系統下的第一個串口*/?{
23?	?????????????????? ?SimpleRead?reader?=?new?SimpleRead();
24?	?????????????? ?}
25?	?????????? ?}
26?	?????? ?}
27?	?? ?}
28?	?
29?	?? ?public?SimpleRead()?{
30?	?????? ?try?{
31?	?????????? ?serialPort?=?(SerialPort)?portId.open("SimpleReadApp",?2000);/*?open方法打開通訊端口，獲得一個CommPort對象。它使程序獨占端口。如果端口正被其他應用程序占用，將使用?CommPortOwnershipListener事件機制，傳遞一個PORT_OWNERSHIP_REQUESTED事件。每個端口都關聯一個?InputStream?何一個OutputStream。如果端口是用open方法打開的，那么任何的getInputStream都將返回相同的數據流對象，除非有close?被調用。有兩個參數，第一個為應用程序名；第二個參數是在端口打開時阻塞等待的毫秒數。*/
32?	?????? ?}?catch?(PortInUseException?e)?{}
33?	?????? ?try?{
34?	?????????? ?inputStream?=?serialPort.getInputStream();/*獲取端口的輸入流對象*/
35?	?????? ?}?catch?(IOException?e)?{}
36?	?? ?try?{
37?	?????????? ?serialPort.addEventListener(this);/*注冊一個SerialPortEventListener事件來監聽串口事件*/
38?	?? ?}?catch?(TooManyListenersException?e)?{}
39?	?
40?	?????? ?serialPort.notifyOnDataAvailable(true);/*數據可用*/
41?	?
42?	?????? ?try?{
43?	?????????? ?serialPort.setSerialPortParams(9600,
44?	?????????????? ?SerialPort.DATABITS_8,
45?	?????????????? ?SerialPort.STOPBITS_1,
46?	?????????????? ?SerialPort.PARITY_NONE);/*設置串口初始化參數，依次是波特率，數據位，停止位和校驗*/
47?	?????? ?}?catch?(UnsupportedCommOperationException?e)?{}
48?	?
49?	?????? ?readThread?=?new?Thread(this);
50?	?????? ?readThread.start();
51?	?? ?}
52?	?
53?	?? ?public?void?run()?{
54?	?????? ?try?{
55?	?????????? ?Thread.sleep(20000);
56?	?????? ?}?catch?(InterruptedException?e)?{}
57?	?? ?}
58?	?
59?	//串口事件
60?	?? ?public?void?serialEvent(SerialPortEvent?event)?{
61?	?
62?	?????? ?switch(event.getEventType())?{
63?	?????? ?case?SerialPortEvent.BI:/*Break?interrupt,通訊中斷*/
64?	?????? ?case?SerialPortEvent.OE:/*Overrun?error，溢位錯誤*/
65?	?????? ?case?SerialPortEvent.FE:/*Framing?error，傳幀錯誤*/
66?	?????? ?case?SerialPortEvent.PE:/*Parity?error，校驗錯誤*/
67?	?????? ?case?SerialPortEvent.CD:/*Carrier?detect，載波檢測*/
68?	?????? ?case?SerialPortEvent.CTS:/*Clear?to?send，清除發送*/
69?	?????? ?case?SerialPortEvent.DSR:/*Data?set?ready，數據設備就緒*/
70?	?????? ?case?SerialPortEvent.RI:/*Ring?indicator，響鈴指示*/
71?	?????? ?case?SerialPortEvent.OUTPUT_BUFFER_EMPTY:/*Output?buffer?is?empty，輸出緩沖區清空*/
72?	?????????? ?break;
73?	?
74?	?????? ?case?SerialPortEvent.DATA_AVAILABLE:/*Data?available?at?the?serial?port，端口有可用數據。讀到緩沖數組，輸出到終端*/
75?	?????????? ?byte[]?readBuffer?=?new?byte[20];
76?	?
77?	?????????? ?try?{
78?	?????????????? ?while?(inputStream.available()?>?0)?{
79?	?????????????????? ?int?numBytes?=?inputStream.read(readBuffer);
80?	?????????????? ?}
81?	?????????????? ?System.out.print(new?String(readBuffer));
82?	?????????? ?}?catch?(IOException?e)?{}
83?	?????????? ?break;
84?	?????? ?}
85?	?? ?}
86?	}
87?	?

?

（2）寫串口

1?	import?java.io.*;
2?	import?java.util.*;
3?	import?javax.comm.*;
4?	?
5?	public?class?SimpleWrite?{
6?	?? ?static?Enumeration?portList;
7?	?? ?static?CommPortIdentifier?portId;
8?	?? ?static?String?messageString?=?"Hello,?world!/n";
9?	?? ?static?SerialPort?serialPort;
10?	?? ?static?OutputStream?outputStream;
11?	?
12?	?? ?public?static?void?main(String[]?args)?{
13?	?????? ?portList?=?CommPortIdentifier.getPortIdentifiers();
14?	?
15?	?????? ?while?(portList.hasMoreElements())?{
16?	?????????? ?portId?=?(CommPortIdentifier)?portList.nextElement();
17?	?????????? ?if?(portId.getPortType()?==?CommPortIdentifier.PORT_SERIAL)?{
18?	?????????????? ?//?if?(portId.getName().equals("COM1"))?{
19?	?????????????? ?if?(portId.getName().equals("/dev/term/a"))?{
20?	?????????????????? ?try?{
21?	?????????????????????? ?serialPort?=?(SerialPort)
22?	?????????????????????????? ?portId.open("SimpleWriteApp",?2000);
23?	?????????????????? ?}?catch?(PortInUseException?e)?{}
24?	?????????????????? ?try?{
25?	?????????????????????? ?outputStream?=?serialPort.getOutputStream();
26?	?????????????????? ?}?catch?(IOException?e)?{}
27?	?????????????????? ?try?{
28?	?????????????????????? ?serialPort.setSerialPortParams(9600,
29?	?????????????????????????? ?SerialPort.DATABITS_8,
30?	?????????????????????????? ?SerialPort.STOPBITS_1,
31?	?????????????????????????? ?SerialPort.PARITY_NONE);
32?	?????????????????? ?}?catch?(UnsupportedCommOperationException?e)?{}
33?	?????????????????? ?try?{
34?	?????????????????????? ?outputStream.write(messageString.getBytes());
35?	?????????????????? ?}?catch?(IOException?e)?{}
36?	?????????????? ?}
37?	?????????? ?}
38?	?????? ?}
39?	?? ?}
40?	}
41?	?

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