think in java interview-高级开发人员面试宝典(八)

面经出了7套，收到许多读者的Email，有许多人说了，这些基础知识是不是为了后面进一步的”通向架构师的道路“做准备的？

对的，你们没有猜错，就是这样的，我一直在酝酿后面的”通向架构师的道路“如何开章。

说实话，我已经在肚子里准备好的后面的”通向架构师的道路“的内容自己觉得如果一下子全拿出来的话，很多人吃不消，因为架构越来越复杂，用到的知识越来越多，而且很多都是各知识点的混合应用。

所以，先以这几套面经来铺路，我们把基础打实了，才能把大楼造的更好。因为，一个架构师首先他是一个程序员，他的基础知识必须非常的扎实，API对于架构师来说已经不太需要eclipse的code insight(即在eclipse编辑器里打一个小点点就可以得到后面的函数），尤其是一些常用的JAVA API来说，是必须熟记于心的。

下面我们继续来几天面经，顺带便复习一下JAVA和数据库的一些基础。

Java IO流的复习

大家平时J2EE写多了，JAVA的IO操作可能都已经生疏了，面试时如果来上这么几道，是不是有点”其实这个问题很简单，可是我就是想不起来“的感觉啊？

呵呵！

JAVA的IO操作太多，我这边挑腾迅，盛大和百度的几道面试题，并整理出答案来供大家参考。

InputFromConsole

这个最简单不过了，从console接受用户输入的字符，如和用户有交互的命令行。

如果你不复习的话，嘿嘿，还真答不出，来看：

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. public class InputFromConsole {  
4.   
5.     /** 
6.      * @param args 
7.      */  
8.     public static void main(String[] args) throws Exception {  
9.         int a = 0;  
10.         byte[] input = new byte[1024];  
11.         System.in.read(input);  
12.         System.out.println("your input is: " + new String(input));  
13.   
14.     }  
15.   
16. }  

package org.sky.io;public class InputFromConsole {/** * @param args */public static void main(String[] args) throws Exception {int a = 0;byte[] input = new byte[1024];System.in.read(input);System.out.println("your input is: " + new String(input));}}

ListDir

列出给出路径下所有的目录，包括子目录

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1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class ListMyDir {  
6.   
7.     /** 
8.      * @param args 
9.      */  
10.     public static void main(String[] args) {  
11.         String fileName = "D:" + File.separator + "tomcat2";  
12.         File f = new File(fileName);  
13.         File[] fs = f.listFiles();  
14.         for (int i = 0; i < fs.length; i++) {  
15.             System.out.println(fs[i].getName());  
16.         }  
17.   
18.     }  
19.   
20. }  

package org.sky.io;import java.io.*;public class ListMyDir {/** * @param args */public static void main(String[] args) {String fileName = "D:" + File.separator + "tomcat2";File f = new File(fileName);File[] fs = f.listFiles();for (int i = 0; i < fs.length; i++) {System.out.println(fs[i].getName());}}}

咦，上面这个程序只列出了一层目录，我们想连子目录一起List出来怎么办？

ListMyDirWithSubDir

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1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class ListMyDirWithSubDir {  
6.   
7.     /** 
8.      * @param args 
9.      */  
10.     public void print(File f) {  
11.         if (f != null) {  
12.             if (f.isDirectory()) {  
13.                 File[] fileArray = f.listFiles();  
14.                 if (fileArray != null) {  
15.                     for (int i = 0; i < fileArray.length; i++) {  
16.                         print(fileArray[i]);  
17.                     }  
18.                 }  
19.             } else {  
20.                 System.out.println(f);  
21.             }  
22.         }  
23.     }  
24.   
25.     public static void main(String[] args) {  
26.         String fileName = "D:" + File.separator + "tomcat2";  
27.         File f = new File(fileName);  
28.         ListMyDirWithSubDir listDir = new ListMyDirWithSubDir();  
29.         listDir.print(f);  
30.   
31.     }  
32. }  

package org.sky.io;import java.io.*;public class ListMyDirWithSubDir {/** * @param args */public void print(File f) {if (f != null) {if (f.isDirectory()) {File[] fileArray = f.listFiles();if (fileArray != null) {for (int i = 0; i < fileArray.length; i++) {print(fileArray[i]);}}} else {System.out.println(f);}}}public static void main(String[] args) {String fileName = "D:" + File.separator + "tomcat2";File f = new File(fileName);ListMyDirWithSubDir listDir = new ListMyDirWithSubDir();listDir.print(f);}}

InputStreamDemo

从外部读入一个文件

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1. package org.sky.io;  
2.   
3. import java.io.File;  
4. import java.io.FileInputStream;  
5. import java.io.FileOutputStream;  
6. import java.io.InputStream;  
7. import java.io.OutputStream;  
8.   
9. public class InputStreamDemo {  
10.     public void readFile(String fileName) {  
11.         File srcFile = new File(fileName);  
12.         InputStream in = null;  
13.         try {  
14.             in = new FileInputStream(srcFile);  
15.             byte[] b = new byte[(int) srcFile.length()];  
16.             for (int i = 0; i < b.length; i++) {  
17.                 b[i] = (byte) in.read();  
18.             }  
19.             System.out.println(new String(b));  
20.         } catch (Exception e) {  
21.             e.printStackTrace();  
22.         } finally {  
23.             try {  
24.                 if (in != null) {  
25.                     in.close();  
26.                     in = null;  
27.                 }  
28.             } catch (Exception e) {  
29.             }  
30.         }  
31.     }  
32.   
33.     public static void main(String[] args) {  
34.         InputStreamDemo id = new InputStreamDemo();  
35.         String src = "D:" + File.separator + "hello.txt";  
36.         id.readFile(src);  
37.     }  
38.   
39. }  

package org.sky.io;import java.io.File;import java.io.FileInputStream;import java.io.FileOutputStream;import java.io.InputStream;import java.io.OutputStream;public class InputStreamDemo {public void readFile(String fileName) {File srcFile = new File(fileName);InputStream in = null;try {in = new FileInputStream(srcFile);byte[] b = new byte[(int) srcFile.length()];for (int i = 0; i < b.length; i++) {b[i] = (byte) in.read();}System.out.println(new String(b));} catch (Exception e) {e.printStackTrace();} finally {try {if (in != null) {in.close();in = null;}} catch (Exception e) {}}}public static void main(String[] args) {InputStreamDemo id = new InputStreamDemo();String src = "D:" + File.separator + "hello.txt";id.readFile(src);}}

OutputStreamDemo

讲完了InputStream来讲OutputStream，输出内容至外部的一个文件

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class OutputStreamDemo {  
6.   
7.     public void writeWithByte() {  
8.         String fileName = "D:" + File.separator + "hello.txt";  
9.         OutputStream out = null;  
10.         File f = new File(fileName);  
11.         try {  
12.             out = new FileOutputStream(f, true);  
13.             String str = "   [Publicity ministry of ShangHai Municipal committee of CPC]";  
14.             byte[] b = str.getBytes();  
15.             out.write(b);  
16.         } catch (Exception e) {  
17.             e.printStackTrace();  
18.         } finally {  
19.             try {  
20.                 if (out != null) {  
21.                     out.close();  
22.                     out = null;  
23.                 }  
24.             } catch (Exception e) {  
25.             }  
26.         }  
27.     }  
28.   
29.     public void writeWithByteArray() {  
30.         String fileName = "D:" + File.separator + "hello.txt";  
31.         OutputStream out = null;  
32.         File f = new File(fileName);  
33.         try {  
34.             out = new FileOutputStream(f, true);  
35.             String str = "   [hello with byte yi ge ge xie]";  
36.             byte[] b = str.getBytes();  
37.             for (int i = 0; i < b.length; i++) {  
38.                 out.write(b[i]);  
39.             }  
40.         } catch (Exception e) {  
41.             e.printStackTrace();  
42.         } finally {  
43.             try {  
44.                 if (out != null) {  
45.                     out.close();  
46.                     out = null;  
47.                 }  
48.             } catch (Exception e) {  
49.             }  
50.         }  
51.     }  
52.   
53.     public static void main(String[] args) {  
54.         OutputStreamDemo od = new OutputStreamDemo();  
55.         od.writeWithByte();  
56.         od.writeWithByteArray();  
57.   
58.     }  
59.   
60. }  

package org.sky.io;import java.io.*;public class OutputStreamDemo {public void writeWithByte() {String fileName = "D:" + File.separator + "hello.txt";OutputStream out = null;File f = new File(fileName);try {out = new FileOutputStream(f, true);String str = "   [Publicity ministry of ShangHai Municipal committee of CPC]";byte[] b = str.getBytes();out.write(b);} catch (Exception e) {e.printStackTrace();} finally {try {if (out != null) {out.close();out = null;}} catch (Exception e) {}}}public void writeWithByteArray() {String fileName = "D:" + File.separator + "hello.txt";OutputStream out = null;File f = new File(fileName);try {out = new FileOutputStream(f, true);String str = "   [hello with byte yi ge ge xie]";byte[] b = str.getBytes();for (int i = 0; i < b.length; i++) {out.write(b[i]);}} catch (Exception e) {e.printStackTrace();} finally {try {if (out != null) {out.close();out = null;}} catch (Exception e) {}}}public static void main(String[] args) {OutputStreamDemo od = new OutputStreamDemo();od.writeWithByte();od.writeWithByteArray();}}

这个Demo里分别用了”writeWithByte“和 ”writeWithByteArray“两种方法，注意查看

CopyFile

我们讲完了InputStream和OutputStream，我们就可以自己实现一个File Copy的功能了，来看

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class CopyFile {  
6.   
7.     public void copy(String src, String des) {  
8.         File srcFile = new File(src);  
9.         File desFile = new File(des);  
10.         InputStream in = null;  
11.         OutputStream out = null;  
12.         try {  
13.             in = new FileInputStream(srcFile);  
14.             out = new FileOutputStream(desFile);  
15.             byte[] b = new byte[(int) srcFile.length()];  
16.             for (int i = 0; i < b.length; i++) {  
17.                 b[i] = (byte) in.read();  
18.             }  
19.             out.write(b);  
20.             System.out.println("copied [" + srcFile.getName() + "]    with    "  
21.                     + srcFile.length());  
22.         } catch (Exception e) {  
23.             e.printStackTrace();  
24.         } finally {  
25.             try {  
26.                 if (out != null) {  
27.                     out.close();  
28.                     out = null;  
29.                 }  
30.             } catch (Exception e) {  
31.             }  
32.             try {  
33.                 if (in != null) {  
34.                     in.close();  
35.                     in = null;  
36.                 }  
37.             } catch (Exception e) {  
38.             }  
39.         }  
40.     }  
41.   
42.     public static void main(String[] args) {  
43.         CopyFile cp = new CopyFile();  
44.         String src = "D:" + File.separator + "UltraEdit.zip";  
45.         String des = "D:" + File.separator + "UltraEdit_Copy.zip";  
46.         long sTime = System.currentTimeMillis();  
47.         cp.copy(src, des);  
48.         long eTime = System.currentTimeMillis();  
49.         System.out.println("Total spend: " + (eTime - sTime));  
50.     }  
51.   
52. }  

package org.sky.io;import java.io.*;public class CopyFile {public void copy(String src, String des) {File srcFile = new File(src);File desFile = new File(des);InputStream in = null;OutputStream out = null;try {in = new FileInputStream(srcFile);out = new FileOutputStream(desFile);byte[] b = new byte[(int) srcFile.length()];for (int i = 0; i < b.length; i++) {b[i] = (byte) in.read();}out.write(b);System.out.println("copied [" + srcFile.getName() + "]    with    "+ srcFile.length());} catch (Exception e) {e.printStackTrace();} finally {try {if (out != null) {out.close();out = null;}} catch (Exception e) {}try {if (in != null) {in.close();in = null;}} catch (Exception e) {}}}public static void main(String[] args) {CopyFile cp = new CopyFile();String src = "D:" + File.separator + "UltraEdit.zip";String des = "D:" + File.separator + "UltraEdit_Copy.zip";long sTime = System.currentTimeMillis();cp.copy(src, des);long eTime = System.currentTimeMillis();System.out.println("Total spend: " + (eTime - sTime));}}

运行后显示：

来看我们被Copy的这个文件的大小：

也不大，怎么用了7秒多？

原是我们没有使用Buffer这个东西，即缓冲，性能会相差多大呢？来看

BufferInputStreamDemo

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class BufferInputStreamDemo {  
6.   
7.     /** 
8.      * @param args 
9.      */  
10.     public void copy(String src, String des) {  
11.         File srcFile = new File(src);  
12.         File desFile = new File(des);  
13.         BufferedInputStream bin = null;  
14.         BufferedOutputStream bout = null;  
15.         try {  
16.             bin = new BufferedInputStream(new FileInputStream(srcFile));  
17.             bout = new BufferedOutputStream(new FileOutputStream(desFile));  
18.             byte[] b = new byte[1024];  
19.             while (bin.read(b) != -1) {  
20.                 bout.write(b);  
21.             }  
22.             bout.flush();  
23.             System.out.println("copied [" + srcFile.getName() + "]    with    "  
24.                     + srcFile.length());  
25.         } catch (Exception e) {  
26.             e.printStackTrace();  
27.         } finally {  
28.             try {  
29.                 if (bout != null) {  
30.                     bout.close();  
31.                     bout = null;  
32.                 }  
33.             } catch (Exception e) {  
34.             }  
35.             try {  
36.                 if (bin != null) {  
37.                     bin.close();  
38.                     bin = null;  
39.                 }  
40.             } catch (Exception e) {  
41.             }  
42.         }  
43.     }  
44.   
45.     public static void main(String[] args) {  
46.         BufferInputStreamDemo bd = new BufferInputStreamDemo();  
47.         String src = "D:" + File.separator + "UltraEdit.zip";  
48.         String des = "D:" + File.separator + "UltraEdit_Copy.zip";  
49.         long sTime = System.currentTimeMillis();  
50.         bd.copy(src, des);  
51.         long eTime = System.currentTimeMillis();  
52.         System.out.println("Total spend: " + (eTime - sTime));  
53.   
54.     }  
55.   
56. }  

package org.sky.io;import java.io.*;public class BufferInputStreamDemo {/** * @param args */public void copy(String src, String des) {File srcFile = new File(src);File desFile = new File(des);BufferedInputStream bin = null;BufferedOutputStream bout = null;try {bin = new BufferedInputStream(new FileInputStream(srcFile));bout = new BufferedOutputStream(new FileOutputStream(desFile));byte[] b = new byte[1024];while (bin.read(b) != -1) {bout.write(b);}bout.flush();System.out.println("copied [" + srcFile.getName() + "]    with    "+ srcFile.length());} catch (Exception e) {e.printStackTrace();} finally {try {if (bout != null) {bout.close();bout = null;}} catch (Exception e) {}try {if (bin != null) {bin.close();bin = null;}} catch (Exception e) {}}}public static void main(String[] args) {BufferInputStreamDemo bd = new BufferInputStreamDemo();String src = "D:" + File.separator + "UltraEdit.zip";String des = "D:" + File.separator + "UltraEdit_Copy.zip";long sTime = System.currentTimeMillis();bd.copy(src, des);long eTime = System.currentTimeMillis();System.out.println("Total spend: " + (eTime - sTime));}}

我们Copy同样一个文件，用了多少时间呢？来看！

丫只用了14毫秒，CALL！！！

ByteArrayDemo

来看看使用ByteArray输出文件吧

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1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class ByteArrayDemo {  
6.   
7.     /** 
8.      * @param args 
9.      */  
10.     public void testByteArray() {  
11.         String str = "HOLLYJESUS";  
12.         ByteArrayInputStream input = null;  
13.         ByteArrayOutputStream output = null;  
14.         try {  
15.             input = new ByteArrayInputStream(str.getBytes());  
16.             output = new ByteArrayOutputStream();  
17.             int temp = 0;  
18.             while ((temp = input.read()) != -1) {  
19.                 char ch = (char) temp;  
20.                 output.write(Character.toLowerCase(ch));  
21.             }  
22.             String outStr = output.toString();  
23.             input.close();  
24.             output.close();  
25.             System.out.println(outStr);  
26.         } catch (Exception e) {  
27.             e.printStackTrace();  
28.         } finally {  
29.             try {  
30.                 if (output != null) {  
31.                     output.close();  
32.                     output = null;  
33.                 }  
34.             } catch (Exception e) {  
35.             }  
36.             try {  
37.                 if (input != null) {  
38.                     input.close();  
39.                     input = null;  
40.                 }  
41.             } catch (Exception e) {  
42.             }  
43.         }  
44.     }  
45.   
46.     public static void main(String[] args) {  
47.         ByteArrayDemo bd = new ByteArrayDemo();  
48.         bd.testByteArray();  
49.   
50.     }  
51.   
52. }  

package org.sky.io;import java.io.*;public class ByteArrayDemo {/** * @param args */public void testByteArray() {String str = "HOLLYJESUS";ByteArrayInputStream input = null;ByteArrayOutputStream output = null;try {input = new ByteArrayInputStream(str.getBytes());output = new ByteArrayOutputStream();int temp = 0;while ((temp = input.read()) != -1) {char ch = (char) temp;output.write(Character.toLowerCase(ch));}String outStr = output.toString();input.close();output.close();System.out.println(outStr);} catch (Exception e) {e.printStackTrace();} finally {try {if (output != null) {output.close();output = null;}} catch (Exception e) {}try {if (input != null) {input.close();input = null;}} catch (Exception e) {}}}public static void main(String[] args) {ByteArrayDemo bd = new ByteArrayDemo();bd.testByteArray();}}

RandomAccess

有种输出流叫Random，你们还记得吗？学习时记得的，工作久了，HOHO，忘了，它到底有什么特殊的地方呢？来看：

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class RandomAccess {  
6.     public void writeToFile() {  
7.         String fileName = "D:" + File.separator + "hello.txt";  
8.         RandomAccessFile randomIO = null;  
9.         try {  
10.   
11.             File f = new File(fileName);  
12.             randomIO = new RandomAccessFile(f, "rw");  
13.             randomIO.writeBytes("asdsad");  
14.             randomIO.writeInt(12);  
15.             randomIO.writeBoolean(true);  
16.             randomIO.writeChar('A');  
17.             randomIO.writeFloat(1.21f);  
18.             randomIO.writeDouble(12.123);  
19.         } catch (Exception e) {  
20.             e.printStackTrace();  
21.         } finally {  
22.             try {  
23.                 if (randomIO != null) {  
24.                     randomIO.close();  
25.                     randomIO = null;  
26.                 }  
27.             } catch (Exception e) {  
28.             }  
29.         }  
30.     }  
31.   
32.     public static void main(String[] args) {  
33.         RandomAccess randomA = new RandomAccess();  
34.         randomA.writeToFile();  
35.     }  
36. }  

package org.sky.io;import java.io.*;public class RandomAccess {public void writeToFile() {String fileName = "D:" + File.separator + "hello.txt";RandomAccessFile randomIO = null;try {File f = new File(fileName);randomIO = new RandomAccessFile(f, "rw");randomIO.writeBytes("asdsad");randomIO.writeInt(12);randomIO.writeBoolean(true);randomIO.writeChar('A');randomIO.writeFloat(1.21f);randomIO.writeDouble(12.123);} catch (Exception e) {e.printStackTrace();} finally {try {if (randomIO != null) {randomIO.close();randomIO = null;}} catch (Exception e) {}}}public static void main(String[] args) {RandomAccess randomA = new RandomAccess();randomA.writeToFile();}}

它输出后的文件是怎么样的呢？

PipeStream

这个流很特殊，我们在线程操作时，两个线程都在运行，这时通过发送一个指令让某个线程do something，我们在以前的jdk1.4中为了实现这样的功能，使用的就是这个PipeStream

先来看两个类，一个叫SendMessage，即发送一个指令。一个叫ReceiveMessage，用于接受指令。

SendMessage

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class SendMessage implements Runnable {  
6.     private PipedOutputStream out = null;  
7.   
8.     public PipedOutputStream getOut() {  
9.         return this.out;  
10.     }  
11.   
12.     public SendMessage() {  
13.         this.out = new PipedOutputStream();  
14.     }  
15.   
16.     public void send() {  
17.   
18.         String msg = "start";  
19.         try {  
20.             out.write(msg.getBytes());  
21.         } catch (Exception e) {  
22.             e.printStackTrace();  
23.         } finally {  
24.             try {  
25.                 if (out != null) {  
26.                     out.close();  
27.                     out = null;  
28.                 }  
29.             } catch (Exception e) {  
30.             }  
31.         }  
32.     }  
33.   
34.     public void run() {  
35.         try {  
36.             System.out.println("waiting for signal...");  
37.             Thread.sleep(2000);  
38.             send();  
39.         } catch (Exception e) {  
40.             e.printStackTrace();  
41.         }  
42.     }  
43. }  

package org.sky.io;import java.io.*;public class SendMessage implements Runnable {private PipedOutputStream out = null;public PipedOutputStream getOut() {return this.out;}public SendMessage() {this.out = new PipedOutputStream();}public void send() {String msg = "start";try {out.write(msg.getBytes());} catch (Exception e) {e.printStackTrace();} finally {try {if (out != null) {out.close();out = null;}} catch (Exception e) {}}}public void run() {try {System.out.println("waiting for signal...");Thread.sleep(2000);send();} catch (Exception e) {e.printStackTrace();}}}

ReceiveMessage

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4.   
5. public class ReceiveMessage implements Runnable {  
6.     private PipedInputStream input = null;  
7.   
8.     public PipedInputStream getInput() {  
9.         return this.input;  
10.     }  
11.   
12.     public ReceiveMessage() {  
13.         this.input = new PipedInputStream();  
14.     }  
15.   
16.     private void receive() {  
17.   
18.         byte[] b = new byte[1000];  
19.         int len = 0;  
20.         String msg = "";  
21.         try {  
22.             len = input.read(b);  
23.             msg = new String(b, 0, len);  
24.             if (msg.equals("start")) {  
25.                 System.out  
26.                         .println("received the start message, receive now can do something......");  
27.                 Thread.interrupted();  
28.             }  
29.         } catch (Exception e) {  
30.             e.printStackTrace();  
31.         } finally {  
32.             try {  
33.                 if (input != null) {  
34.                     input.close();  
35.                     input = null;  
36.                 }  
37.             } catch (Exception e) {  
38.             }  
39.         }  
40.     }  
41.   
42.     public void run() {  
43.         try {  
44.             receive();  
45.         } catch (Exception e) {  
46.         }  
47.     }  
48. }  

package org.sky.io;import java.io.*;public class ReceiveMessage implements Runnable {private PipedInputStream input = null;public PipedInputStream getInput() {return this.input;}public ReceiveMessage() {this.input = new PipedInputStream();}private void receive() {byte[] b = new byte[1000];int len = 0;String msg = "";try {len = input.read(b);msg = new String(b, 0, len);if (msg.equals("start")) {System.out.println("received the start message, receive now can do something......");Thread.interrupted();}} catch (Exception e) {e.printStackTrace();} finally {try {if (input != null) {input.close();input = null;}} catch (Exception e) {}}}public void run() {try {receive();} catch (Exception e) {}}}

如何使用这两个类呢？

TestPipeStream

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. public class TestPipeStream {  
4.   
5.     /** 
6.      * @param args 
7.      */  
8.     public static void main(String[] args) {  
9.         SendMessage send = new SendMessage();  
10.         ReceiveMessage receive = new ReceiveMessage();  
11.         try {  
12.             send.getOut().connect(receive.getInput());  
13.             Thread t1 = new Thread(send);  
14.             Thread t2 = new Thread(receive);  
15.             t1.start();  
16.             t2.start();  
17.   
18.         } catch (Exception e) {  
19.             e.printStackTrace();  
20.         }  
21.   
22.     }  
23.   
24. }  

package org.sky.io;public class TestPipeStream {/** * @param args */public static void main(String[] args) {SendMessage send = new SendMessage();ReceiveMessage receive = new ReceiveMessage();try {send.getOut().connect(receive.getInput());Thread t1 = new Thread(send);Thread t2 = new Thread(receive);t1.start();t2.start();} catch (Exception e) {e.printStackTrace();}}}

注意这边有一个send.getOut().connect(receive.getInput());

这个方法就把两个线程”connect“起来了。

Serializable的IO操作

把一个类序列化到磁盘上，怎么做？

先来看我们要序列化的一个Java Bean

Person

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.Serializable;  
4.   
5. public class Person implements Serializable {  
6.   
7.     private String name = "";  
8.     private String age = "";  
9.     private String personId = "";  
10.   
11.     public String getName() {  
12.         return name;  
13.     }  
14.   
15.     public void setName(String name) {  
16.         this.name = name;  
17.     }  
18.   
19.     public String getAge() {  
20.         return age;  
21.     }  
22.   
23.     public void setAge(String age) {  
24.         this.age = age;  
25.     }  
26.   
27.     public String getPersonId() {  
28.         return personId;  
29.     }  
30.   
31.     public void setPersonId(String personId) {  
32.         this.personId = personId;  
33.     }  
34.   
35.     public String getCellPhoneNo() {  
36.         return cellPhoneNo;  
37.     }  
38.   
39.     public void setCellPhoneNo(String cellPhoneNo) {  
40.         this.cellPhoneNo = cellPhoneNo;  
41.     }  
42.   
43.     private String cellPhoneNo = "";  
44. }  

package org.sky.io;import java.io.Serializable;public class Person implements Serializable {private String name = "";private String age = "";private String personId = "";public String getName() {return name;}public void setName(String name) {this.name = name;}public String getAge() {return age;}public void setAge(String age) {this.age = age;}public String getPersonId() {return personId;}public void setPersonId(String personId) {this.personId = personId;}public String getCellPhoneNo() {return cellPhoneNo;}public void setCellPhoneNo(String cellPhoneNo) {this.cellPhoneNo = cellPhoneNo;}private String cellPhoneNo = "";}

下面来看序列化的操作

SerializablePersonToFile

[java] view plaincopyprint?

1. package org.sky.io;  
2.   
3. import java.io.*;  
4. import java.util.*;  
5.   
6. public class SerializablePersonToFile {  
7.   
8.     /** 
9.      * @param args 
10.      */  
11.     private List<Person> initList() {  
12.         List<Person> userList = new ArrayList<Person>();  
13.         Person loginUser = new Person();  
14.         loginUser.setName("sam");  
15.         loginUser.setAge("30");  
16.         loginUser.setCellPhoneNo("13333333333");  
17.         loginUser.setPersonId("111111111111111111");  
18.         userList.add(loginUser);  
19.         loginUser = new Person();  
20.         loginUser.setName("tonny");  
21.         loginUser.setAge("31");  
22.         loginUser.setCellPhoneNo("14333333333");  
23.         loginUser.setPersonId("111111111111111111");  
24.         userList.add(loginUser);  
25.         loginUser = new Person();  
26.         loginUser.setName("jim");  
27.         loginUser.setAge("28");  
28.         loginUser.setCellPhoneNo("15333333333");  
29.         loginUser.setPersonId("111111111111111111");  
30.         userList.add(loginUser);  
31.         loginUser = new Person();  
32.         loginUser.setName("Simon");  
33.         loginUser.setAge("30");  
34.         loginUser.setCellPhoneNo("17333333333");  
35.         loginUser.setPersonId("111111111111111111");  
36.         userList.add(loginUser);  
37.         return userList;  
38.     }  
39.   
40.     private  void serializeFromFile() {  
41.         FileInputStream fs = null;  
42.         ObjectInputStream ois = null;  
43.         try {  
44.             fs = new FileInputStream("person.txt");  
45.             ois = new ObjectInputStream(fs);  
46.             List<Person> userList = (ArrayList<Person>) ois.readObject();  
47.             for (Person p : userList) {  
48.                 System.out.println(p.getName() + "   " + p.getAge() + "   "  
49.                         + p.getCellPhoneNo() + "   " + p.getCellPhoneNo());  
50.             }  
51.         } catch (Exception ex) {  
52.             ex.printStackTrace();  
53.         } finally {  
54.             try {  
55.                 if (ois != null) {  
56.                     ois.close();  
57.                 }  
58.             } catch (Exception e) {  
59.             }  
60.             try {  
61.                 if (fs != null) {  
62.                     fs.close();  
63.                 }  
64.             } catch (Exception e) {  
65.             }  
66.         }  
67.     }  
68.   
69.     private void serializeToFile() {  
70.         List<Person> userList = new ArrayList<Person>();  
71.         userList = initList();  
72.         FileOutputStream fs = null;  
73.         ObjectOutputStream os = null;  
74.         try {  
75.             fs = new FileOutputStream("person.txt");  
76.             os = new ObjectOutputStream(fs);  
77.             os.writeObject(userList);  
78.         } catch (Exception ex) {  
79.             ex.printStackTrace();  
80.         } finally {  
81.             try {  
82.                 if (os != null) {  
83.                     os.close();  
84.                 }  
85.             } catch (Exception e) {  
86.             }  
87.             try {  
88.                 if (fs != null) {  
89.                     fs.close();  
90.                 }  
91.             } catch (Exception e) {  
92.             }  
93.         }  
94.     }  
95.   
96.     public static void main(String[] args) {  
97.         SerializablePersonToFile sf = new SerializablePersonToFile();  
98.         sf.serializeToFile();  
99.         sf.serializeFromFile();  
100.     }  
101.   
102. }  

package org.sky.io;import java.io.*;import java.util.*;public class SerializablePersonToFile {/** * @param args */private List<Person> initList() {List<Person> userList = new ArrayList<Person>();Person loginUser = new Person();loginUser.setName("sam");loginUser.setAge("30");loginUser.setCellPhoneNo("13333333333");loginUser.setPersonId("111111111111111111");userList.add(loginUser);loginUser = new Person();loginUser.setName("tonny");loginUser.setAge("31");loginUser.setCellPhoneNo("14333333333");loginUser.setPersonId("111111111111111111");userList.add(loginUser);loginUser = new Person();loginUser.setName("jim");loginUser.setAge("28");loginUser.setCellPhoneNo("15333333333");loginUser.setPersonId("111111111111111111");userList.add(loginUser);loginUser = new Person();loginUser.setName("Simon");loginUser.setAge("30");loginUser.setCellPhoneNo("17333333333");loginUser.setPersonId("111111111111111111");userList.add(loginUser);return userList;}private  void serializeFromFile() {FileInputStream fs = null;ObjectInputStream ois = null;try {fs = new FileInputStream("person.txt");ois = new ObjectInputStream(fs);List<Person> userList = (ArrayList<Person>) ois.readObject();for (Person p : userList) {System.out.println(p.getName() + "   " + p.getAge() + "   "+ p.getCellPhoneNo() + "   " + p.getCellPhoneNo());}} catch (Exception ex) {ex.printStackTrace();} finally {try {if (ois != null) {ois.close();}} catch (Exception e) {}try {if (fs != null) {fs.close();}} catch (Exception e) {}}}private void serializeToFile() {List<Person> userList = new ArrayList<Person>();userList = initList();FileOutputStream fs = null;ObjectOutputStream os = null;try {fs = new FileOutputStream("person.txt");os = new ObjectOutputStream(fs);os.writeObject(userList);} catch (Exception ex) {ex.printStackTrace();} finally {try {if (os != null) {os.close();}} catch (Exception e) {}try {if (fs != null) {fs.close();}} catch (Exception e) {}}}public static void main(String[] args) {SerializablePersonToFile sf = new SerializablePersonToFile();sf.serializeToFile();sf.serializeFromFile();}}

这边先把Person输出到Person.txt，再从Person.txt里反序列化出这个Person的Java Bean。

先讲这么些吧！

Java的流操作还有很多，这些是经常会被面试到的，很基础，因此经常被考到。

以前听一个读IT的同学说过，这些IO操作，就算没有Eclipse编辑器的话，用文本编辑器也应该能够写出来，你写不出只能代表你的基础太弱了。