不解压直接读取压缩包中的文件

项目中需要用到不解压压缩包，直接读取压缩包中的文件，于是研究下了，现整理出来。

读取指定文件有两种思路，一种是在循环中遍历进行判断，另一种是直接通过文件名进行获取；

• 通过文件名直接获取
  使用zipFile.getEntry(“文件名”)方法获取

public static void readZipFile1(String file,String fileName) throws Exception {  
        ZipFile zf = new ZipFile(file);
        ZipEntry ze = zf.getEntry(fileName);
        InputStream in = zf.getInputStream(ze);
        BufferedReader br = new BufferedReader(new InputStreamReader(in));
        String line;
        StringBuffer result = new StringBuffer();
        while ((line = br.readLine()) != null) {  
        result.append(line+"\n");
    }
        System.out.println(result);
}

• 循环遍历中根据文件名进行判断

public static void readZipFile2(String file,String fileName) throws Exception {  
        ZipFile zf = new ZipFile(file);  
        InputStream in = new BufferedInputStream(new FileInputStream(file));  
        ZipInputStream zin = new ZipInputStream(in);  
        ZipEntry ze;
        StringBuffer result = new StringBuffer();
        while ((ze = zin.getNextEntry()) != null) {  
            if (ze.isDirectory()) {
               continue;
            } else {  
                long size = ze.getSize();
                String name = ze.getName();
                if (size > 0 && fileName.equals(name)) {  
                    BufferedReader br = new BufferedReader(new InputStreamReader(zf.getInputStream(ze)));
                    String line;  
                    while ((line = br.readLine()) != null) {  
                        result.append(line+"\n");
                    }  
                    br.close();  
                }  
            }  
        }
        System.out.println(result);
        zin.closeEntry();  
}

public static void readZipFile3(String file, String fileName) {  
        try {  
            ZipFile zipFile = new ZipFile(file); 
            StringBuffer result = new StringBuffer();
            Enumeration<ZipEntry> enu = (Enumeration<ZipEntry>) zipFile.entries();  
            while (enu.hasMoreElements()) {  
                ZipEntry zipElement = (ZipEntry) enu.nextElement();  
                InputStream read = zipFile.getInputStream(zipElement);  
                String name = zipElement.getName();  
                if (name != null && fileName.equals(name)) {
                    BufferedReader br = new BufferedReader(new InputStreamReader(read));
                    String line;  
                    while ((line = br.readLine()) != null) {  
                        result.append(line+"\n");
                    }  
                    br.close();
                }  
            }
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
}

• 在main方法中调用

public static void main(String[] args) throws Exception {
    readZipFile("G://report.zip", "1004165931.html");
}

通过上面的几种方法可以实现直接从有压缩包中读取指定文件，当然我们也可以把指定文件写入到指定目录中再打开，实现代码如下：

/**
  * 
  * @param file 压缩包路径
  * @param saveRootDirectory 写入文件夹路径
  * @param fileName 文件名
  * @throws FileNotFoundException
  * @throws IOException
  */
public static void writeZipFile(String file,String saveRootDirectory,String fileName) throws FileNotFoundException, IOException {
        int len = 0;
        ZipFile zf = new ZipFile(file);
        ZipEntry ze = zf.getEntry(fileName);
        InputStream read = zf.getInputStream(ze);
        File writeFile = new File(saveRootDirectory + fileName);
        if (!writeFile.exists()) {  
            File rootDirectoryFile = new File(saveRootDirectory);  
            //创建目录  
            if (!rootDirectoryFile.exists()) {  
                rootDirectoryFile.mkdirs();  
            } 
            //创建文件  
            writeFile.createNewFile();

            BufferedOutputStream write = new BufferedOutputStream(new FileOutputStream(file));
            //写入文件内容
            while ((len = read.read()) != -1) {
                write.write(len);
            }
            write.flush();  
            write.close();  
        }

        read.close();  
}

上面的代码实现了，把file路径下的压缩包中的名为fileName的文件写入到saveRootDirectory目录下。