JAVA经典总结

Java经典实例(第二版)
1. 获取环境变量
Java代码
1.    System.getenv("PATH");
2.    System.getenv("JAVA_HOME");  

2. 获取系统属性
Java代码
1.    System.getProperty("pencil color");  // 得到属性值
2.    java -Dpencil color=green
3.    System.getProperty("java.specification.version");  // 得到Java版本号
4.    Properties p = System.getProperties();  // 得到所有属性值
5.    p.list(System.out);  

3. StringTokenizer
Java代码
1.    // 能够同时识别, 和 |
2.    StringTokenizer st = new StringTokenizer("Hello, World|of|Java", ", |");
3.    while (st.hasMoreElements()) {
4.        st.nextToken();
5.    }
6.
7.    // 把分隔符视为token
8.    StringTokenizer st = new StringTokenizer("Hello, World|of|Java", ", |",  true);  

4. StringBuffer(同步)和StringBuilder(非同步)
Java代码
1.    StringBuilder sb = new StringBuilder();
2.    sb.append("Hello");
3.    sb.append("World");
4.    sb.toString();
5.    new StringBuffer(a).reverse();   // 反转字符串  

5. 数字
Java代码
1.    // 数字与对象之间互相转换 - Integer转int
2.    Integer.intValue();
3.
4.    // 浮点数的舍入
5.    Math.round()
6.
7.    // 数字格式化
8.    NumberFormat
9.
10.    // 整数 -> 二进制字符串
11.    toBinaryString() 或valueOf()
12.
13.    // 整数 -> 八进制字符串
14.    toOctalString()
15.
16.    // 整数 -> 十六进制字符串
17.    toHexString()
18.
19.    // 数字格式化为罗马数字
20.    RomanNumberFormat()
21.
22.    // 随机数
23.    Random r = new Random();
24.    r.nextDouble();
25.    r.nextInt();  

6. 日期和时间
Java代码
1.    // 查看当前日期
2.    Date today = new Date();
3.    Calendar.getInstance().getTime();
4.
5.    // 格式化默认区域日期输出
6.    DateFormat df = DateFormat.getInstance();
7.    df.format(today);
8.
9.    // 格式化制定区域日期输出
10.    DateFormat df_cn = DateFormat.getDateInstance(DateFormat.FULL, Locale.CHINA);
11.    String now = df_cn.format(today);
12.
13.    // 按要求格式打印日期
14.    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
15.    sdf.format(today);
16.
17.    // 设置具体日期
18.    GregorianCalendar d1 = new GregorianCalendar(2009, 05, 06);  // 6月6日
19.    GregorianCalendar d2 = new GregorianCalendar();  // 今天
20.    Calendar d3 = Calendar.getInstance();  // 今天
21.    d1.getTime();  // Calendar或GregorianCalendar转成Date格式
22.    d3.set(Calendar.YEAR, 1999);
23.    d3.set(Calendar.MONTH, Calendar.APRIL);
24.    d3.set(Calendar.DAY_OF_MONTH, 12);
25.
26.    // 字符串转日期
27.    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
28.    Date now = sdf.parse(String);
29.
30.    // 日期加减
31.    Date now = new Date();
32.    long t = now.getTime();
33.    t += 700*24*60*60*1000;
34.    Date then = new Date(t);
35.
36.    Calendar now = Calendar.getInstance();
37.    now.add(Calendar.YEAR, -2);
38.
39.    // 计算日期间隔(转换成long来计算)
40.    today.getTime() - old.getTime();
41.
42.    // 比较日期
43.    Date 类型，就使用equals(), before(), after()来计算
44.    long类型，就使用==, <, >来计算
45.
46.    // 第几日
47.    使用 Calendar的get()方法
48.    Calendar c = Calendar.getInstance();
49.    c.get(Calendar.YEAR);
50.
51.    // 记录耗时
52.    long start = System.currentTimeMillis();
53.    long end = System.currentTimeMillis();
54.    long elapsed = end - start;
55.    System.nanoTime();  //毫秒
56.
57.    // 长整形转换成秒
58.    Double.toString(t/1000D);  

7. 结构化数据
Java代码
1.    // 数组拷贝
2.    System.arrayCopy(oldArray, 0, newArray, 0, oldArray.length);
3.
4.    // ArrayList
5.    add(Object o)  // 在末尾添加给定元素
6.    add(int i, Object o)  // 在指定位置插入给定元素
7.    clear()  // 从集合中删除全部元素
8.    Contains(Object o)  // 如果Vector包含给定元素，返回真值
9.    get(int i)  // 返回 指定位置的对象句柄
10.    indexOf(Object o)  // 如果找到给定对象，则返回其索引值；否则，返回-1
11.    remove(Object o)  // 根据引用删除对象
12.    remove(int i)  // 根据 位置删除对象
13.    toArray()  // 返回包含集合对象的数组
14.
15.    // Iterator
16.    List list = new ArrayList();
17.    Iterator it = list.iterator();
18.    while (it.hasNext())
19.    Object o = it.next();
20.
21.    // 链表
22.    LinkedList list = new LinkedList();
23.    ListIterator it = list.listIterator();
24.    while (it.hasNext())
25.    Object o = it.next();
26.
27.    // HashMap
28.    HashMap<String, String> hm = new HashMap<String, String>();
29.    hm.get(key);  // 通过key得到value
30.    hm.put("No1", "Hexinyu");
31.    hm.put("No2", "Sean");
32.    // 方法1: 获取全部键值
33.    Iterator<String> it = hm.values().iterator();
34.    while (it.hasNext()) {
35.        String myKey = it.next();
36.        String myValue = hm.get(myKey);
37.    }
38.    // 方法2: 获取全部键值
39.    for (String key : hm.keySet()) {
40.        String myKey = key;
41.        String myValue = hm.get(myKey);
42.    }
43.
44.    // Preferences - 与系统相关的用户设置，类似名-值对
45.    Preferences prefs = Preferences.userNodeForPackage(ArrayDemo.class);
46.    String text = prefs.get("textFontName", "lucida-bright");
47.    String display = prefs.get("displayFontName", "lucida-balckletter");
48.    System.out.println(text);
49.    System.out.println(display);
50.    // 用户设置了新值，存储回去
51.    prefs.put("textFontName", "new-bright");
52.    prefs.put("displayFontName", "new-balckletter");
53.
54.    // Properties - 类似名-值对，key和value之间，可以用"="，":"或空格分隔，用"#" 和"!"注释
55.    InputStream in = MediationServer.class.getClassLoader().getResourceAsStream("msconfig.properties");
56.    Properties prop = new Properties();
57.    prop.load(in);
58.    in.close();
59.    prop.setProperty(key, value);
60.    prop.getProperty(key);
61.
62.    // 排序
63.    1. 数组：Arrays.sort(strings);
64.    2. List：Collections.sort(list);
65.    3. 自定义类：class SubComp implements Comparator
66.        然 后使用Arrays.sort(strings, new SubComp())
67.
68.    // 两个接口
69.    1. java.lang.Comparable: 提供对象的自然排序，内置于类中
70.       int compareTo(Object o);
71.        boolean equals(Object o2);
72.    2. java.util.Comparator: 提供特定的比较方法
73.       int compare(Object o1, Object o2)
74.
75.    // 避免重复排序，可以使用TreeMap
76.    TreeMap sorted = new TreeMap(unsortedHashMap);
77.
78.    // 排除重复元素
79.    Hashset hs - new HashSet();
80.
81.    // 搜索对象
82.    binarySearch(): 快 速查询 - Arrays, Collections
83.    contains(): 线型搜 索 - ArrayList, HashSet, Hashtable, linkedList, Properties, Vector
84.    containsKey(): 检 查集合对象是否包含给定 - HashMap, Hashtable, Properties, TreeMap
85.    containsValue(): 主 键(或给定值) - HashMap, Hashtable, Properties, TreeMap
86.    indexOf(): 若 找到给定对象，返回其位置 - ArrayList, linkedList, List, Stack, Vector
87.    search(): 线 型搜素 - Stack
88.
89.    // 集合转数组
90.    toArray();
91.
92.    // 集合总结
93.    Collection: Set - HashSet, TreeSet
94.    Collection: List - ArrayList, Vector, LinkedList
95.    Map: HashMap, HashTable, TreeMap  

8. 泛型与foreach
Java代码
1.    // 泛型
2.    List<String> myList = new ArrayList<String>();
3.
4.    // foreach
5.    for (String s : myList) {
6.        System.out.println(s);
7.    }  

9. 面向对象
Java代码
1.    // toString()格式化
2.    public class ToStringWith {
3.        int x, y;
4.        public ToStringWith(int anX, int aY) {
5.            x = anX;
6.            y = aY;
7.        }
8.        public String toString() {
9.            return "ToStringWith[" + x + "," + y + "]";
10.        }
11.        public static void main(String[] args) {
12.            System.out.println(new ToStringWith(43, 78));
13.        }
14.    }
15.
16.    // 覆盖equals方法
17.    public boolean equals(Object o) {
18.        if (o == this)  // 优化
19.            return true;
20.        if (!(o instanceof EqualsDemo))  // 可投射到这个类
21.            return false;
22.        EqualsDemo other = (EqualsDemo)o;  // 类型转换
23.        if (int1 != other.int1)  // 按字段比较
24.            return false;
25.        if (!obj1.equals(other.obj1))
26.            return false;
27.        return true;
28.    }
29.
30.    // 覆盖hashcode方法
31.    private volatile int hashCode = 0;  //延迟初始化
32.    public int hashCode() {
33.        if (hashCode == 0) {
34.            int result = 17;
35.            result = 37 * result + areaCode;
36.        }
37.        return hashCode;
38.    }
39.
40.    // Clone方法
41.    要 克隆对象，必须先做两步: 1. 覆盖对象的clone()方法; 2. 实现空的Cloneable接口
42.    public class Clone1 implements Cloneable {
43.        public Object clone() {
44.            return super.clone();
45.        }
46.    }
47.
48.    // Finalize方法
49.    Object f = new Object() {
50.        public void finalize() {
51.            System.out.println("Running finalize()");
52.        }
53.    };
54.    Runtime.getRuntime().addShutdownHook(new Thread() {
55.        public void run() {
56.            System.out.println("Running Shutdown Hook");
57.        }
58.    });
59.    在 调用System.exit(0);的时候，这两个方法将被执行
60.
61.    // Singleton模式
62.    // 实现1
63.    public class MySingleton() {
64.        public static final MySingleton INSTANCE = new MySingleton();
65.        private MySingleton() {}
66.    }
67.    // 实现2
68.    public class MySingleton() {
69.        public static MySingleton instance = new MySingleton();
70.        private MySingleton() {}
71.        public static MySingleton getInstance() {
72.            return instance;
73.        }
74.    }
75.
76.    // 自定义异常
77.    Exception: 编 译时检查
78.    RuntimeException: 运行时检查
79.    public class MyException extends RuntimeException {
80.        public MyException() {
81.            super();
82.        }
83.        public MyException(String msg) {
84.            super(msg);
85.        }
86.    }  

10. 输入和输出
Java代码
1.    // Stream, Reader, Writer
2.    Stream: 处 理字节流
3.    Reader/Writer: 处理字符，通用Unicode
4.
5.    // 从标准输入设备读数据
6.    1. 用System.in的BufferedInputStream()读取字节
7.        int b = System.in.read();
8.          System.out.println("Read data: " + (char)b);  // 强 制转换为字符
9.    2. BufferedReader 读取文本
10.        如果从Stream转成Reader，使用 InputStreamReader类
11.        BufferedReader is = new BufferedReader(new
12.          InputStreamReader(System.in));
13.          String inputLine;
14.          while ((inputLine = is.readLine()) != null) {
15.              System.out.println(inputLine);
16.              int val = Integer.parseInt(inputLine);  // 如果inputLine为整数
17.        }
18.          is.close();
19.
20.    // 向标准输出设备写数据
21.    1. 用System.out的println()打印数据
22.    2. 用PrintWriter打印
23.        PrintWriter pw = new PrintWriter(System.out);
24.          pw.println("The answer is " + myAnswer + " at this time.");
25.
26.    // Formatter类
27.    格 式化打印内容
28.    Formatter fmtr = new Formatter();
29.    fmtr.format("%1$04d - the year of %2$f", 1951, Math.PI);
30.    或 者System.out.printf();或者System.out.format();
31.
32.    // 原始扫描
33.    void doFile(Reader is) {
34.        int c;
35.        while ((c = is.read()) != -1) {
36.            System.out.println((char)c);
37.        }
38.    }
39.
40.    // Scanner扫描
41.    Scanner 可以读取File, InputStream, String, Readable
42.    try {
43.        Scanner scan = new Scanner(new File("a.txt"));
44.        while (scan.hasNext()) {
45.            String s = scan.next();
46.        }
47.        } catch (FileNotFoundException e) {
48.            e.printStackTrace();
49.        }
50.    }
51.
52.    // 读取文件
53.    BufferedReader is = new BufferedReader(new FileReader("myFile.txt"));
54.    BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("bytes.bat"));
55.    is.close();
56.    bos.close();
57.
58.    // 复制文件
59.    BufferedIutputStream is = new BufferedIutputStream(new FileIutputStream("oldFile.txt"));
60.    BufferedOutputStream os = new BufferedOutputStream(new FileOutputStream("newFile.txt"));
61.    int b;
62.    while ((b = is.read()) != -1) {
63.        os.write(b);
64.    }
65.    is.close();
66.    os.close();
67.
68.    // 文件读入字符串
69.    StringBuffer sb = new StringBuffer();
70.    char[] b = new char[8192];
71.    int n;
72.    // 读一个块，如果有字符，加入缓冲区
73.    while ((n = is.read(b)) > 0) {
74.        sb.append(b, 0, n);
75.    }
76.    return sb.toString();
77.
78.    // 重定向标准流
79.    String logfile = "error.log";
80.    System.setErr(new PrintStream(new FileOutputStream(logfile)));
81.
82.    // 读写不同字符集文本
83.    BufferedReader chinese = new BufferedReader(new InputStreamReader(new FileInputStream("chinese.txt"), "ISO8859_1"));
84.    PrintWriter standard = new PrintWriter(new OutputStreamWriter(new FileOutputStream("standard.txt"), "UTF-8"));
85.
86.    // 读取二进制数据
87.    DataOutputStream os = new DataOutputStream(new FileOutputStream("a.txt"));
88.    os.writeInt(i);
89.    os.writeDouble(d);
90.    os.close();
91.
92.    // 从指定位置读数据
93.    RandomAccessFile raf = new RandomAccessFile(fileName, "r");  // r表示已 只读打开
94.    raf.seek(15);  // 从15开始读
95.    raf.readInt();
96.    raf.radLine();
97.
98.    // 串行化对象
99.    对象串 行化，必须实现Serializable接口
100.    // 保存 数据到磁盘
101.    ObjectOutputStream os = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(FILENAME)));
102.    os.writeObject(serialObject);
103.    os.close();
104.    // 读出数据
105.    ObjectInputStream is = new ObjectInputStream(new FileInputStream(FILENAME));
106.    is.readObject();
107.    is.close();
108.
109.    // 读写Jar或Zip文档
110.    ZipFile zippy = new ZipFile("a.jar");
111.    Enumeration all = zippy.entries();  // 枚举值列出所有文件清单
112.    while (all.hasMoreElements()) {
113.        ZipEntry entry = (ZipEntry)all.nextElement();
114.        if (entry.isFile())
115.            println("Directory: " + entry.getName());
116.
117.        // 读写文件
118.        FileOutputStream os = new FileOutputStream(entry.getName());
119.        InputStream is = zippy.getInputStream(entry);
120.        int n = 0;
121.        byte[] b = new byte[8092];
122.        while ((n = is.read(b)) > 0) {
123.            os.write(b, 0, n);
124.            is.close();
125.            os.close();
126.        }
127.    }
128.
129.    // 读写gzip文档
130.    FileInputStream fin = new FileInputStream(FILENAME);
131.    GZIPInputStream gzis = new GZIPInputStream(fin);
132.    InputStreamReader xover = new InputStreamReader(gzis);
133.    BufferedReader is = new BufferedReader(xover);
134.    String line;
135.    while ((line = is.readLine()) != null)
136.        System.out.println("Read: " + line);  

11. 目录和文件操作
Java代码
1.    // 获取文件信息
2.    exists(): 如 果文件存在，返回true
3.    getCanonicalPath(): 获 取全名
4.    getName(): 文件名
5.    getParent(): 父 目录
6.    canRead(): 如果文件可读，返回true
7.    canWrite(): 如 果文件可写，返回true
8.    lastModified(): 文 件更新时间
9.    length(): 文件大小
10.    isFile(): 如 果是文件，返回true
11.    ifDirectory(): 如 果是目录，返回true
12.    要 调用文件的这些方法，必须
13.    File f = new File(fileName);
14.
15.    // 创建文件
16.    File f = new File("c:\\test\\mytest.txt");
17.    f.createNewFile();  // 创建mytest.txt文件到test目录下
18.
19.    // 修改文件名
20.    File f = new File("c:\\test\\mytest.txt");
21.    f.renameTo(new File("c:\\test\\google.txt"));
22.    把 mytest.txt修改成google.txt
23.
24.    // 删除文件
25.    File f = new File("c:\\test\\mytest.txt");
26.    f.delete();
27.
28.    // 临时文件
29.    File f = new File("C:\\test");  // 指定一个文件夹
30.    // 在test文件夹中创建foo前缀，tmp后缀的临时文件
31.    File tmp = File.createTempFile("foo", "tmp", f);
32.    tmp.deleteOnExit();  // 在程序结束时删除该临时文件
33.
34.    // 更改文件属性
35.    setReadOnly(): 设 置为只读
36.    setlastModified(): 设置最后更改时间
37.
38.    // 列出当前文件夹的文件列表
39.    String[] dir = new java.io.File(".").list();
40.    java.util.Arrays.sort(dir);
41.    for (int i = 0; i < dir.length; i++) {
42.        System.out.println(dir[i]);
43.    }
44.
45.    // 过滤文件列表
46.    class OnlyJava implements FilenameFilter {
47.        public boolean accept(File dir, String s) {
48.            if (s.endsWith(".java") || s.endsWith(".class") || s.endsWith(".jar"))
49.                return true;
50.        }
51.    }
52.
53.    // 获取根目录
54.    File[] rootDir = File.listRoots();
55.    for (int i = 0; i < rootDir.length; i++) {
56.        System.out.println(rootDir[i]);
57.    }
58.
59.    // 创建新目录
60.    new File("/home/ian/bin").mkdir();  // 如果"/home/ian"存在，则可以创建bin目录
61.    new File("/home/ian/bin").mkdirs();  // 如果"/home/ian"不存在，会创建所有的目录  

12. 国际化和本地化
Java代码
1.    // I18N资源
2.    ResourceBundle rb = ResourceBundle.getBundle("Menus");
3.    String label = rb.getString("exit.label");
4.    // ResourceBundle相当于名值对，获取Menus按钮的区域属性
5.    Menus_cn.properties: 不 同区域的属性文件
6.
7.    // 列出有效区域
8.    Locale[] list = Locale.getAvailableLocales()；
9.
10.    // 指定区域
11.    Locale cnLocale = Locale.CHINA;
12.
13.    // 设置默认区域
14.    Locale.setDefault(Locale.CHINA);
15.
16.    // 格式化消息
17.    public class MessageFormatDemo {
18.        static Object[] data = {
19.            new java.util.Date(),
20.            "myfile.txt",
21.            "could nto be opened"
22.        };
23.        public static void main(String[] args) {
24.            String result = MessageFormat.format("At {0,time} on {0,date}, {1} {2}.", data);
25.            System.out.println(result);
26.        }
27.    }
28.    输 出: At 10:10:08 on 2009-6-18, myfile.txt could nto be opened.
29.
30.    // 从资源文件中读消息
31.    Widgets.properties 在com.sean.cook.chap11下
32.    ResourceBundle rb = ResourceBundle.getBundle("com.sean.cook.chap11.Widgets");
33.    String propt = rb.getString("filedialogs.cantopen.string");
34.    String result = MessageFormat.format(rb.getString("filedialogs.cantopen.format"), data);  

13. 网络客户端
Java代码
1.    // 访问服务器
2.    Socket socket = new Socket("127.0.0.1", 8080);
3.    // todo something
4.    socket.close();
5.
6.    // 查找网络地址
7.    InetAddress.getByName(hostName).getHostAddress()); // 根据主机名得到IP地址
8.    InetAddress.getByName(ipAddr).getHostName()); // 根据IP地址得到主机名
9.
10.    // 连接具体异常
11.    UnknownHostException
12.    NoRouteToHostException
13.    ConnectException
14.
15.    // Socket读写文本数据
16.    BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
17.    String remoteTime = in.readline();
18.    PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
19.    out.print("send message to client \r\n");
20.    out.flush();
21.
22.    // Socket读写二进制数据
23.    DataInputStream in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
24.    long remoteTime = (long)(in.readUnsignedByte() << 24);
25.    DataOutputStream out = new DataOutputStream(socket.getOutputStream(), true);
26.
27.    // Socket读写串行化数据
28.    ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(socket.getInputStream()));
29.    Object o = in.readObject();
30.    if (o instanceof Date) // 验证对象类型
31.    ObjectOutputStream out = new ObjectOutputStream(socket.getOutputStream(), true);
32.
33.    // UDP数据报
34.    private final static int PACKET_SIZE = 1024;
35.
36.    String host = "EV001B389673DE";
37.    InetAddress serverAddr = InetAddress.getByName(host);
38.    DatagramSocket socket = new DatagramSocket();
39.    byte[] buffer = new byte[PACKET_SIZE]; // 分配数据缓冲空间
40.    DatagramPacket packet = new DatagramPacket(buffer, PACKET_SIZE, serverAddr, 8080);
41.    packet.setLength(PACKET_SIZE-1); // 设置数据长度
42.    socket.send(packet);
43.    socket.receive(packet); // 接收数据  

14. 服务器端: Socket
Java代码
1.    // 创建ServerSocket
2.    ServerSocket serverSocket;
3.    Socket clientSocket;
4.
5.    serverSocket = new ServerSocket(9999);
6.    while ((clientSocket = serverSocket.accept()) != null) {
7.        System.out.println("Accept from client " + s.getInetAddress());
8.        s.close();
9.    }
10.
11.    // 监听内部网
12.    public static final short PORT = 9999;
13.    public static final String INSIDE_HOST = "acmewidgets-inside"; // 网络接口名
14.    public static final int BACKLOG = 10; // 待发数
15.    serverSocket = new ServerSocket(PORT, BACKLOG, InetAddress.getByName(INSIDE_HOST));
16.
17.    // 返回相应对象
18.    ServerSocket serverSocket =  new ServerSocket(9999);;
19.    Socket clientSocket;
20.    BufferedReader in = null;
21.    PrintWriter out = null;
22.    while (true) {
23.        clientSocket = serverSocket.accept();
24.        in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream(), "8859_1"));
25.        out = new PrintWriter(new OutputStreamWriter(clientSocket.getOutputStream(), "8859_1"), true);
26.        String echoLine;
27.        while ((echoLine = in.readLine()) != null) {
28.            System.out.println("Read " + echoLine);
29.            out.print(echoLine + "\r\n");
30.        }
31.    }
32.    以 上例子返回字符串，如果返回二进制，则使用DataOutputStream；返回对象，使用ObjectOutputStream
33.
34.    // 处理多客户端
35.    需要 把接收数据的处理放入多线程中
36.    public class EchoServerThreaded {
37.        public static final int ECHOPORT = 7;
38.        public static final int NUM_THREADS = 4;
39.
40.        public static void main(String[] av) {
41.            new EchoServerThreaded(ECHOPORT, NUM_THREADS);
42.        }
43.
44.        public EchoServerThreaded2(int port, int numThreads) {
45.            ServerSocket servSock;
46.            Socket clientSocket;
47.            try {
48.                servSock = new ServerSocket(ECHOPORT);
49.            } catch(IOException e) {
50.                throw new RuntimeException("Could not create ServerSocket " + e);
51.            }
52.            for (int i = 0; i < numThreads; i++) {
53.                new Handler(servSock, i).start();
54.            }
55.        }
56.    }
57.    class Handler extends Thread {
58.        ServerSocket servSock;
59.        int threadNumber;
60.
61.        Handler(ServerSocket s, int i) {
62.            super();
63.            servSock = s;
64.            threadNumber = i;
65.            setName("Thread " + threadNumber);
66.        }
67.
68.        public void run() {
69.            while (true) {
70.                try {
71.                    System.out.println(getName() + " waiting");
72.                    Socket clientSocket;
73.                    synchronized (servSock) {
74.                        clientSocket = servSock.accept();
75.                    }
76.                    System.out.println(getName() + " starting, IP=" + clientSocket.getInetAddress());
77.                    BufferedReader is = new BufferedReader(new InputStreamReader(
78.                        clientSocket.getInputStream()));
79.                    PrintStream os = new PrintStream(clientSocket.getOutputStream(), true);
80.                    String line;
81.                    while ((line = is.readLine()) != null) {
82.                        os.print(line + "\r\n");
83.                        os.flush();
84.                    }
85.                    System.out.println(getName() + " ENDED ");
86.                    clientSocket.close();
87.                } catch (IOException ex) {
88.                    System.out.println(getName() + ": IO Error on socket " + ex);
89.                    return;
90.                }
91.            }
92.        }
93.    }
94.
95.    // 使用SSL和JSSE保护Web服务器
96.    SSLServerSocketFactory ssf = (SSLServerSocketFactory)SSLServerSocketFactory.getDefault()；
97.    ServerSocket serverSocket = ssf.createServerSocket(8080);
98.
99.    // Log4j
100.    Level 级别: DEBUG < INFO < WARN < ERROR < FATAL < OFF
101.    Appender: 输 出信息
102.    ConsoleAppender: 输出控制台 System.out
103.
104.    // 找到网络接口
105.    Enumeration list = NetworkInterface.getNetworkInterfaces();
106.    while (list.hasMoreElements()) {
107.        NetworkInterface iface = (NetworkInterface)list.nextElement();
108.        System.out.println(iface.getDisplayName());
109.        Enumeration addrs = iface.getInetAddresses();
110.        while (addrs.hasMoreElements()) {
111.            InetAddress addr = (InetAddress)addrs.nextElement();
112.            System.out.println(addr);
113.        }
114.    }  

15. Java Mail
Java代码
1.    // 发送Mail
2.    protected String msgRecIp = "hxydream@163.com";
3.    protected String msgSubject = "babytree";
4.    protected String msgCc = "nobody@erewhon.com";
5.    protected String msgBody = "test body";
6.    protected Session session;
7.    protected Message msg;
8.
9.    public void doSend() {
10.        // 创建属性文件
11.        Properties props = new Properties();
12.        props.put("mail.smtp.host", "mailhost");
13.        // 创建Session对象
14.        session = Session.getDefaultInstance(props, null);
15.        session.setDebug(true);
16.        msg = new MimeMessage(session); // 创建邮件
17.        msg. setFrom(new InternetAddress("nobody@host.domain"));
18.        InternetAddress toAddr = new InternetAddress(msgRecIp);
19.        msg.addRecipient(Message.RecipientType.TO, toAddr);
20.        InternetAddress ccAddr = new InternetAddress(msgCc);
21.        msg.addRecipient(Message.RecipientType.CC, ccAddr);
22.        msg.setSubject(msgSubject);
23.        msg.setText(msgBody);
24.        Transport.send(msg);
25.    }
26.
27.    // 发送MIME邮件
28.    Multipart mp = new MimeMultipart();
29.    BodyPart textPart = new MimeBodyPart();
30.    textPart.setText(message_body);  // 设置类型"text/plain"
31.    BodyPart pixPart = new MimeBodyPart();
32.    pixPart.setContent(html_data, "text/html");
33.    mp.addBodyPart(textPart);
34.    mp.addBodyPart(pixPart);
35.    mesg.setContent(mp);
36.    Transport.send(mesg);
37.
38.    // 读Mail
39.    Store store = session.getStore(protocol);
40.    store.connect(host, user, password);
41.    Folder rf;
42.    rf = store.getFolder(root);
43.    rf = store.getDefaultFolder();
44.    rf.open(Folder.READ_WRITE);  

16. 数据库访问
Java代码
1.    // JDO
2.    Properties p = new Properties();
3.    p.load(new FileInputStream("jdo.properties"));
4.    PersistenceManagerFactory pmf = JDOHelper.getPersistenceManagerFactory(p);
5.    PersistenceManager pm = pmf.getPersistenceManager();
6.    // 提交数据
7.    pm.currentTransaction().begin();
8.    if (o instanceof Collection) {
9.        pm.makePersistentAll((Collection) o);
10.    } else {
11.        pm.makePersistent(o);
12.    }
13.    pm.currentTransaction().commit();
14.    pm.close();
15.    // 取出数据
16.    Object[] data = new Object[3];
17.    pm.retrieveAll(data);
18.    for (int i = 0; i < data.length; i++) {
19.        System.out.println(data[i]);
20.    }
21.    pm.close();
22.
23.    // 数据操作
24.    Class clz = Class.forName("oracle.jdbc.driver.OracleDriver");
25.    String dbUrl = "jdbc:oracle:thin:@192.168.0.23:1521#:nms";
26.    Connection conn = DriverManager.getConnection(dbUrl, "su", "1234");
27.    Statement stmt = conn.createStatement();
28.    ResultSet rs = stmt.executeQuery("select * from pmtable");
29.    while (rs.next()) {
30.        String name = rs.getString(1);
31.        String otherName = rs.getString("name");
32.    }
33.
34.    // 使用PreparedStatement提高性能，除了查询，都使用executeUpdate执行操作
35.    PreparedStatement pstmt = conn.prepareStatement("select * from pmtable where name = ?");
36.    pstmt.setString(1, "sean");
37.    ResultSet rs = pstmt.executeQuery();
38.
39.    // 调用存储过程
40.    CallableStatement cs = conn.prepareCall("{ call ListDefunctUsers }");
41.    ResultSet rs = cs.executeQuery();
42.
43.    // 显示数据库表信息
44.    DatabaseMetaData meta = conn.getMetaData();
45.    meta.getDatabaseProductName();
46.    meta.getDatabaseProductVersion();
47.    meta.getDefaultTransactionIsolation();  

17. XML
    SAX: 在读取文档提取相应的标记事件(元素起始、元素结束、文档起始)
    DOM: 在内存中构造与文档中元素相应的树，可以遍历、搜索、修改
    DTD: 验证文档是否正确
    JAXP: 用于XML处理的Java API
    Castor: 开源项目，用于Java对象与XML映射
Java代码
1.    // 从对象中生成XML
2.    private final static String FILENAME = "serial.xml";
3.    public static void main(String[] args) throws IOException {
4.        String a = "hard work and best callback";
5.        new SerialDemoXML().write(a);
6.        new SerialDemoXML().dump();
7.    }
8.    public void write(Object obj) throws IOException {
9.        XMLEncoder os = new XMLEncoder(new BufferedOutputStream(new FileOutputStream(FILENAME)));
10.        os.writeObject(obj);
11.        os.close();
12.    }
13.    public void dump() throws IOException {
14.        XMLDecoder out = new XMLDecoder(new BufferedInputStream(new FileInputStream(FILENAME)));
15.        System.out.println(out.readObject());
16.        out.close();
17.    }
18.    serial.xml 格式内容如下:
19.    <?xml version="1.0" encoding="UTF-8"?>
20.    <java version="1.6.0_02" class="java.beans.XMLDecoder">
21.        <string>hard work and best callback</string>
22.    </java>
23.    控 制台输出
24.    hard work and best callback
25.
26.    // XSLT转换XML
27.    XSLT 可以用来对输出格式进行各种控制
28.    Transformer tx = TransformerFactory.newInstance().newTransformer(new StreamSource("people.xml"));
29.    tx.transform(new StreamSource("people.xml"), new StreamResult("people.html"));
30.
31.    // 用SAX解析XML - 主要用于查找关键元素，不用全文遍历
32.    public SaxLister() throws SAXException, IOException {
33.        XMLReader parser = XMLReaderFactory.createXMLReader("org.apache.xerces.parsers.SAXParser");
34.        parser.setContentHandler(new PeopleHandler());
35.        parser.parse("C:\\StudySource\\javacooksrc2\\xml\\people.xml");
36.    }
37.    class PeopleHandler extends DefaultHandler {
38.        boolean parent = false;
39.        boolean kids = false;
40.        public void startElement(String nsURI, String localName, String rawName, Attributes attr) throws SAXException {
41.            System.out.println("startElement: " +  localName + "," + rawName);
42.            if (rawName.equalsIgnoreCase("name"))
43.                parent = true;
44.            if (rawName.equalsIgnoreCase("children"))
45.            kids = true;
46.        }
47.        public void characters(char[] ch, int start, int length) {
48.            if (parent) {
49.                System.out.println("Parent: " + new String(ch, start, length));
50.                parent = false;
51.            } else if (kids) {
52.                System.out.println("Children: " + new String(ch, start, length));
53.                kids = false;
54.            }
55.        }
56.        public PeopleHandler() throws SAXException {
57.            super();
58.        }
59.    }
60.
61.    // DOM解析XML - 遍历整个树
62.    String uri = "file:" + new File("C:\\StudySource\\javacooksrc2\\xml\\people.xml").getAbsolutePath();
63.    DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
64.    DocumentBuilder builder = factory.newDocumentBuilder();
65.    Document doc = builder.parse(uri);
66.    NodeList nodes = doc.getChildNodes();
67.    for (int i = 0; i < nodes.getLength(); i++) {
68.        Node n = nodes.item(i);
69.        switch (n.getNodeType()) {
70.        case Node.ELEMENT_NODE:
71.            // todo
72.            break;
73.        case Node.TEXT_NODE:
74.            // todo
75.            break;
76.        }
77.    }
78.
79.    // 使用DTD或者XSD验证
80.    定 义好DTD或XSD文件
81.    XmlDocument doc = XmlDocument.createXmlDocument(uri, true);
82.
83.    // 用DOM生成XML
84.    DocumentBuilderFactory fact = DocumentBuilderFactory.newInstance();
85.    DocumentBuilder parser = fact.newDocumentBuilder();
86.    Document doc = parser.newDocument();
87.    Node root = doc.createElement("Poem");
88.    doc.appendChild(root);
89.    Node stanza = doc.createElement("Stanza");
90.    root.appendChild(stanza);
91.    Node line = doc.createElement("Line");
92.    stanza.appendChild(line);
93.    line.appendChild(doc.createTextNode("Once, upon a midnight dreary"));
94.    line = doc.createElement("Line");
95.    stanza.appendChild(line);
96.    line.appendChild(doc.createTextNode("While I pondered, weak and weary"));  

18. RMI
Java代码
1.    a. 定义 客户端与服务器之间的通信接口
2.    public interface RemoteDate extends Remote {
3.        public Date getRemoteDate() throws RemoteException;
4.        public final static String LOOKUPNAME = "RemoteDate";
5.    }
6.
7.    b. 编 写RMI服务器
8.    public class RemoteDateImpl extends UnicastRemoteObject implements RemoteDate {
9.        public RemoteDateImpl() throws RemoteException {
10.            super();
11.        }
12.        public Date getRemoteDate() throws RemoteException {
13.            return new Date();
14.        }
15.    }
16.    RemoteDateImpl im = new RemoteDateImpl();
17.    System.out.println("DateServer starting...");
18.    Naming.rebind(RemoteDate.LOOKUPNAME, im);
19.    System.out.println("DateServer ready.");
20.
21.    c. 运 行rmic生成stub
22.    javac RemoteDateImpl.java
23.    rmic RemoteDateImpl
24.
25.    d. 编 写客户端
26.    netConn = (RemoteDate)Naming.lookup(RemoteDate.LOOKUPNAME);
27.    Date today = netConn.getRemoteDate();
28.    System.out.println(today.toString());
29.
30.    e. 确 保RMI注册表运行
31.    rmiregistry
32.
33.    f. 启 动服务器
34.    java RemoteDateImpl
35.
36.    g. 运 行客户端
37.    java DateClient  

19. 包和包装机制
    jar cvf /tmp/test.jar .  // 当前目录压缩到test.jar中
    jar xvf /tmp/test.jar  // 把test.jar解压到当前目录
    从指定class运行jar文件
    a. Main-Class: HelloWord  // 注意中间有一个空格
    b. jar cvmf manifest.mf hello.jar HelloWorld.class
    c. java -jar hello.jar

20. Java线程
Java代码
1.    // 停止线程 - 不要使用stop()方法
2.    private boolean done = false;
3.    public void run() {
4.        while (!done) {
5.            //todo
6.        }
7.    }
8.    public void shutDown() {
9.        done = true;
10.    }
11.    可 以调用shutDown()方法来结束线程
12.
13.    // 如果读取IO的时候出现堵塞，那么可以使用下面方法
14.    public void shutDown() throws IOException {
15.        if (io != null)
16.            io.close();
17.    }
18.
19.    // 启动一线程，等待控制台输入，使用join()方法来暂停当前线程，直到其他线程调用
20.    Thread t = new Thread() {
21.        public void run() {
22.            System.out.println("Reading");
23.            try {
24.                System.in.read();
25.            } catch (IOException e) {
26.                System.err.println(e);
27.            }
28.            System.out.println("Thread finished.");
29.        }
30.    };
31.    System.out.println("Starting");
32.    t.start();
33.    System.out.println("Joining");
34.    try {
35.        t.join();
36.    } catch (InterruptedException e) {
37.        System.out.println("Who dares imterrupt my sleep?");
38.    }
39.    System.out.println("Main finished.");
40.
41.    // 加锁保证同步
42.    Lock lock = new ReentrantLock();
43.    try {
44.        lock.lock();
45.        // todo
46.    } finally {
47.        lock.unlock();
48.    }
49.
50.    线 程通信wait(), notify(), notifyAll()
51.    生产者-消费者模式
52.    Executors  

21. 内省或“命令类的类”
Java代码
1.    // 反射
2.    Class c = Class.forName("java.lang.String");
3.    Constructor[] cons = c.getConstructors();
4.    for (int i = 0; i < cons.length; i++) {
5.        System.out.println(cons[i].toString());
6.    }
7.    Method[] meths = c.getMethods();
8.    for (int i = 0; i < meths.length; i++) {
9.        System.out.println(meths[i].toString());
10.    }
11.
12.    // 动态装载类
13.    Class c = Class.forName("java.lang.String");
14.    Object obj = c.newInstance();
15.
16.    // 通过反射调用类的方法
17.    class X {
18.        public void master(String s) {
19.            System.out.println("Working on \"" + s + "\"");
20.        }
21.    }
22.    Class clx = X.class;
23.    Class[] argTypes = {String.class};
24.    Method worker = clx.getMethod("master", argTypes);
25.    Object[] theData = {"Chocolate chips"};
26.    worker.invoke(new X(), theData);
27.    输 出: Working on "Chocolate chips"  

22. Java与其他语言的结合
Java代码
1.    // 执行CMD命令，在Eclipse控制台输出
2.    Process p = Runtime.getRuntime().exec("C:/StudySource/ver.cmd");
3.    p.waitFor(); // 等待命令执行完
4.    BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
5.    String s;
6.    while ((s = br.readLine()) != null)
7.        System.out.println(s);
8.
9.    // 调用Jython - 计算22.0/7
10.    BSFManager manager = new BSFManager();
11.    String[] fntypes = {".py"};
12.    manager.registerScriptingEngine("jython", "org.apache.bsf.engines.jython.JythonEngine", fntypes);
13.    Object r = manager.eval("jython", "testString", 0, 0, "22.0/7");
14.    System.out.println("Result type is " + r.getClass().getName());
15.    System.out.println("Result value is " + r);