需求：

这一步也非常简单，主要是demo下ZipEntry的用法，就是把一个以zip扩展名结尾的文件进行解压缩。

所以我就直接贴上代码了：

实现：

1. /** 
2.  
3. * This class will handle the folder zipper related operations 
4.  
5. * 
6.  
7.  * @author cwang58 
8.  
9. * @created date: Aug 4, 2012 
10.  
11. */ 
12.  
13. public class FolderZipper implements IFolderZipper { 
14.  
15.   
16.  
17.          private static Logger logger = LoggerFactory.getLogger(FolderZipper.class); 
18.  
19.   
20.  
21.          /** 
22.  
23.          * to unzip a zip file ,it will read all the entries in the zip file if the 
24.  
25.          * entry is a folder ,then it will created a folder structure (including the 
26.  
27.          * parent folder structure) if the entry is a file ,then it use file output 
28.  
29.          * stream to output this file 
30.  
31.          * 
32.  
33.           * @param zipFileName 
34.  
35.          *            the zip file name 
36.  
37.          * @param destPath 
38.  
39.          *            the path that we want to zip to 
40.  
41.          */ 
42.  
43.          public void unzip(String zipFileName, String destPath) throws Exception { 
44.  
45.   
46.  
47.                  // verify the parameters 
48.  
49.                  if (zipFileName == null || zipFileName.trim().equals(EMPTY_STRING)) { 
50.  
51.                           if (logger.isErrorEnabled()) { 
52.  
53.                                    logger.error("zipFileName parameter can't be null"); 
54.  
55.                           } 
56.  
57.                           throw new ParameterNullException(ZIP_UNZIP_ERROR); 
58.  
59.                  } 
60.  
61.   
62.  
63.                  if (destPath == null) { 
64.  
65.   
66.  
67.                           if (logger.isErrorEnabled()) { 
68.  
69.                                    logger.error("destPath parameter can't be null"); 
70.  
71.                           } 
72.  
73.                           throw new ParameterNullException("ZIP_UNZIP_ERROR"); 
74.  
75.                  } 
76.  
77.   
78.  
79.                  // verify the zip file 's file extension (only support ZIP) 
80.  
81.                  if (!zipFileName.trim().endsWith(ZIP_EXTENSION)) { 
82.  
83.   
84.  
85.                           if (logger.isErrorEnabled()) { 
86.  
87.                                    logger.error("the zip file MUST BE end with zip suffix"); 
88.  
89.                           } 
90.  
91.                           throw new ParameterInvalidException(ZIP_UNZIP_ERROR); 
92.  
93.                  } 
94.  
95.   
96.  
97.                  try { 
98.  
99.   
100.  
101.                           FileInputStream fis = new FileInputStream(zipFileName); 
102.  
103.                           ZipInputStream zis = new ZipInputStream(fis); 
104.  
105.                           ZipEntry ze = null; 
106.  
107.   
108.  
109.                           if (destPath.equals(DOT)) 
110.  
111.                                    destPath = EMPTY_STRING; 
112.  
113.   
114.  
115.                           while ((ze = zis.getNextEntry()) != null) { 
116.  
117.   
118.  
119.                                    // if the zipEntry is a folder 
120.  
121.                                    // then must create the folder structure 
122.  
123.                                    if (ze.isDirectory()) { 
124.  
125.   
126.  
127.                                             if (logger.isDebugEnabled()) { 
128.  
129.                                                      logger.debug("Processing folder:" + ze.getName()); 
130.  
131.                                             } 
132.  
133.   
134.  
135.                                             // construct the dirName by string concating the destpath 
136.  
137.                                             // and the foldername 
138.  
139.                                             String dirName = destPath + ze.getName(); 
140.  
141.   
142.  
143.                                             // creating the folder structure 
144.  
145.                                             File f = new File(dirName); 
146.  
147.                                             f.mkdirs(); 
148.  
149.   
150.  
151.                                             if (logger.isDebugEnabled()) { 
152.  
153.                                                     logger.debug("The folder " + f.getAbsolutePath() 
154.  
155.                                                                       + " is created"); 
156.  
157.                                             } 
158.  
159.                                    } 
160.  
161.   
162.  
163.                                    // if the zipEntry file is a file 
164.  
165.                                    // then use a FileOutputStream to write this file 
166.  
167.                                    else { 
168.  
169.                                             if (logger.isDebugEnabled()) { 
170.  
171.                                                     logger.debug("Processing file: " + ze.getName()); 
172.  
173.                                             } 
174.  
175.   
176.  
177.                                             // construct the fileName by string concating the destpath 
178.  
179.                                             // and the foldername 
180.  
181.                                            String fileName = destPath + ze.getName(); 
182.  
183.                                             File f = new File(fileName); 
184.  
185.   
186.  
187.                                             // open a FileOutputStream to write this file 
188.  
189.                                             FileOutputStream fos = new FileOutputStream(f); 
190.  
191.                                             int tmp = -1; 
192.  
193.                                             while ((tmp = zis.read()) != -1) { 
194.  
195.                                                     fos.write(tmp); 
196.  
197.                                             } 
198.  
199.                                             zis.closeEntry(); 
200.  
201.                                             fos.close(); 
202.  
203.   
204.  
205.                                             if (logger.isDebugEnabled()) { 
206.  
207.                                                     logger.debug("The file " + f.getAbsolutePath() 
208.  
209.                                                                       + " is created"); 
210.  
211.                                             } 
212.  
213.                                    } 
214.  
215.                           } 
216.  
217.                           zis.close(); 
218.  
219.   
220.  
221.                  } catch (FileNotFoundException ex) { 
222.  
223.   
224.  
225.                           if (logger.isErrorEnabled()) { 
226.  
227.                                    logger.error("file not found"); 
228.  
229.                           } 
230.  
231.                           throw new InvalidFolderZipperException(ZIP_UNZIP_ERROR, ex); 
232.  
233.   
234.  
235.                  } catch (IOException ex) { 
236.  
237.   
238.  
239.                           if (logger.isErrorEnabled()) { 
240.  
241.                                    logger.error("io exception occured"); 
242.  
243.                           } 
244.  
245.   
246.  
247.                           throw new InvalidFolderZipperException(ZIP_UNZIP_ERROR, 
248.  
249.                                             ex); 
250.  
251.                  } 
252.  
253.          } 
254.  
255.   
256.  
257. } 

(1)在47-93行还是对入参进行严格的检查。

(2)第103行打开了一个ZipInputStream，然后在第115行对于这个zip文件里的所有的条目进行遍历。

(3)第119-159行对于条目是一个目录的情况进行了处理，它必须去相应的创建目录结构

(4)第163-215行对于条目是个文件的情况进行了处理，它打开一个文件输出流然后写这个Zip的文件条目到目标目录下相应的位置。